A Mineralogical Study of the Hemo-Ilmenite Ore from Lac Tio a Mineralogical Study of the Hemo—Ilmenite Ore

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GM 35775 A MINERALOGICAL STUDY OF THE HEMO-ILMENITE ORE FROM LAC TIO A MINERALOGICAL STUDY OF THE HEMO—ILMENITE ORE

FROM LAC TIO, QUEBEC

Michel Bergeron

Ministère de l'Énergie et des Ressources Gouvernement du Québec Documentation Technique

QUE: 1980 MAPS 0 5

No. QM: 36/1S

Feb. 73 I

A MINERALOGICAL STUDY OF HEMO-ILMENITE ORE FROM LAC TIO, OUEBEC

ABSTRACT

The Lac Tio orebody consista of a large deposit of massive hemo-ilmenite within andesine anorthosite rocks. The deposit has been mined continuously since 1951 by the Quebec Iron and Titanium Corporation.

It is located some 22 miles north of Havre St-Pierre, a small sea port on the north coast of the St.Lawrence River.

The purpose of this work has been to study in detail the mineralogy and chemistry of the hemo-ilmenite ore in order to detect possible chemical and mineralogical variations within the orebody. The work involved the systematic study of 135 specimens cif ore by X-ray diffraction, the complete chemical analyses of 48 high purity hemo- ilmenite concentrates, and the microscopic and electron probe examination of some 40 polished sections.

Our study shows that the Fe-Ti ore is almost entirely made up of hemo-ilmenite, of average composition 70% ilmenite and 30% hematite, unmixed to a regular intergrowth of hematite and ilmenite. Microprobe analyses and crystal chemical considerations indicate that the average composition of the unmixed phases is : (144.11814n. 00.4Fe.873 C1.004)Ti°3

203. Other minerals identified in the ore and (Fe,971y.014 A1 012Cr.004) consist of accessory amounts of plagioclase (An46, commonly antiperthitic), pleonaste spinel, and pyrite, as well as minor or trace quantities of magnetite, chlorite, hypersthene, zalcite, zircon, corundum, apatite, chalcopyrite, millerite, pyrrhotite, Co-Ni sulphides (linaeite series), II

rutile and anatase. rrimary magnetite is almost absent in the ore; the most common magnetite is secondary in origin and together with anatase and rutile has formed at the expense of hemo-ilmenite during the subsolidus stage. The study of the variation of the hemp-ilme:.tite chemistry throughout the orebody indicates that the mineral deviates little from the average composition. All attempts to find regular or stratigraphic variations of the minor elements (Mg, Mn, Cr, Al, V) of the hemo-ilmenite were unsuccessful.

The geology End origin of the deposit is reviewed in the light of our data. It is suggested that the ore crystallized from an oxide melt that separated by liquid immiscibility early in the evolution of the regional anorthosit:e mass{,f. From textural evidence it is concluded that b emo-ilmenite accumulated by crystal settling. The lack of fractionation trends in the ore is attributed to repeated injections of oxide magmas and to a slow rate of crystallization which favored adcumslus growth of the hemo-ilmenite crystals. ETUDE MINERALOGIQUE D;: MINERAI D'HEMO-ILMENITE DU LAC TIO QUEBEC

Résumé

Le gisement du Lac Tio est constitué d'un amas massif d'hémo- ilménite â l'intérieur d'un complexe anorthositique de type anorthosite

A and.ésine. Ce dépôt, exploité depuis 1951 par la société Fer et Titane du Québec, est situés environ 22 milles au nord de Havre St-Pierre, petit port de mer sur la rive nord du fleuve St-Laurent.

L"objectif de ce travail était de déceler d'éventuelles variations minéralogiques et chimiques dans le gisement par une étude détail- lée de la composition du minerai. Le travail est basé sur l'é,ude systé- matique de 135 échantillons de minerai par diffraction des rayons-X, sur l'analyse chimique de 48 concentrés d'hémo-ilménite de très grande pureté et sur l'examen au microscope et à la microsonde d'environ 40 sections polies.

Nous avons montré que le minerai de fer et de titane est com-

posé presqu'exclusivement d'hémo-ilménite qui se présente sous forme d'une intercroissance lamellaire régulière formée d'environ 70% d'ilmé- nite et de 30% d'hématite. Les analyses à la microsonde et les données

ct'istallochimiques in-liguent que la composition moyenne de chacune des .W4)TiO3 et phases exsudeés est la suivante (Mg.118M.004Fe.873Ca .004)203. Les minéraux. . - c.essoires identifiés dans (Fe.0.,1V.014M .012G1 le minerai sont le plagioclase (An46, communément an~::lperthitique), le

spinelle de type pléonaste et la pyrite. De petites quantités, voire des

traces, de magnétite, chalcopyrite, chlorite;, rutile, hyperathène, pyrrho- IV

tine, anatase, zircon, corindon, apatite, willerite,calci:e et des sulfures de cobalt et de nickel (série linaeite) sont aussi 1résentes. La magnétite primaire est presque inexistante dans le minerai, la magnétite la plus commune dans le minerai est d'origine secondaire: islle s'est formée, tout comme le rutile et l'anatase, à varti.r d'hémo-iiménite lors du stade subsolidus. L'étude des vari itior i. de la compositaio. chimique de l'hémo-ilménite dans le gisement montre qu'elle s'écarte p:u de la composition moyenne. Tous nos efforts visant à prouver l'existence de variations régulières ou stratigraphiques dans les éléments mi•aeurs (Mg,

Mn, Cr, Al, V) d:~ i'hémo-ilménite ont été infructueux.

Une étude de la genèse et de l'histoire du gisement à la lumière de nos résultats, nous amène à considérer que le minerai a cristallisé à partir d'un fondu d'oxydes ("ore magma") qui ze serait formé par immisci- bilit:é au tout début de l'évolution du massif anorthositique régional.

Les données texturales du minerai n7us portent à conclure que le liquide

magmatique injecté dans l'anorthosite solidifiée a cristallisé par cris-

tallisat-`.on fractionnée sous l'influence de la gravité. L'absence de

variations stratigraphiques dans le minerai est attribuée à des injections

répétées de magma et à un taux de cristallisation plutôt lent favorisant

ainsi une croissance "adcumulus" des cristaux d'hémo-ilménite.

m'Ans a matneaao:visxawmimmaimasianfiauaAial ■ ,dHUM~~es~►~~~e~~ ri~wa~s oo~

TABLE OF CONTENTS 2241 ABSTRACT INTRODUCTION 1 Chapter I GEOLOGY OF THE LAC ALLARD AREA 3 1.1 Introduction 3 1.2 Location 3 1.3 Previous Work and History of the Area 6 1.4 Physical Geography 8 1.5 General Geology . .. 10 1.5.1 "Grenville Series" of Retty (1944) ...... 12 1.5.1.1 Quartzite 12 1.5.1.2 Hornblende Gneiss and Biotite Gneiss 12 1.5.1.3 Garnetiferous Gneiss 12 1.5.1.4 Less Common Rocks of the "Grenville Series" in the Area 12

1.5.2 "Morin Series" of Retty (1944) 13

1.5.2.1 Anorthosite ., 13 1.5.2.2 Anorthosite with Coarse Pyroxene Crystals 14 1.5.2.3, Ilmenite Rich Anorthosite 114 1.5.2.4 Anorthosite Dykes 15 1.5.3 Granitic Rocks 15

1.5.4 Diorite, Gabbro and Metagabbro 4,1 15 1.5.5 Pleistocene and Recent 15 1.6 Structural Geology 17 1.7 Economic Geology 18 1.7.1 Introduction 18 1.7.2 The Lac Tio Deposit 19 1.7.2.1 General Mineralogy and Chemistry

of the Lac Tio Deposit ...... 22 1.7.2.2 Faulting of the Lac Tic Oreboc1r .. 26 1.7.2.3 Magnetic Property of the Lac Tio Hemo--Ilmenite ....."...... w.... 32 __ Yaffe Chapter II

MINERALOGY OF THE LAC TIO HEMO-I_LMENITE DEPOSIT 35

2.1 Introduction 35 2.2 Description of Minerals 35 2.2.1 Hemo-Ilmenite 35 2.2.1.1 General Megascopic and Microscopic Characteristics 35. 2.2.1.2 Chemical Composition of Hlmo-I2menite 39 2.2.1.3 Minor Element Distribution in Unmixed Ilmenite and Hematite ... 47 2.2.1.4 Lattice Parameters and Composition of Unmixed Hematite and Ilmenite 44 2.2.1.5 Distribution and Variation of ilmenite and Hematite in the Ore7lody 49

2.2.2 Plagiaiciase . .... 51 2.2.3 Sulphides . 54

2.2.3.1 General Distribution . .. 54

2.2.3.2 Chemistry of the Sulphides ...... 56 2.2.1+ Spinel 5T 2.2.5 Magnetite 61 2.2.6 Rutile and Anatase 65 2.2.7 Chlorite and Biotite 68 2.2.8 Apatite, Corundum and Zircon 71 2.2.9 Hypersthene and Calcite 75 2.3 Mineralogical Summary 75 Chapter III GEOCHEMISTRY OF HEMO-ILMENITES FROM THE LAC TIO DEPOSIT 8o 3.1 Introduction 80 3.2 Selection and Preparation of Material for Study 80 3.3 Analytical Methods and Preparation of an Hemo- Ilmenite Standard 83 3.4 Chemistry of Hemo-Ilmenites in the Deposit 85 3.5 Chemical Variations of Hemo-Ilmenite in the Orebody 87 3.6 Inter-element Correlations in Hemo-Ilmenites 94 3.7 Synopsis of Hemo-Ilmeni.se Chemistry 103

romaimummiummull

VII

Page Chapter IV

CERTAIN ASPECTS OF THE PETROLOGY AND ORIGIN OF THE LAC TIO DEPOSIT 106

4.1 Introduction 106 4.2 Metallogenic Traits of the Lac Tio Deposit ' 106 4.3 Crystallization and Evolution of the Hemo-ilmenite Magma 109 4.4 Subsolidus Evolution of the Hemo•-Ilmenite 114 4.5 Concluding Statement 118 BIBLIOGRAPHY 119 ACKNOWLEDGEMENTS . 124

APPENDICE:

I Preparation and Chemical Analysis of 48 Lac Tio Hemo- Ilmenite Concentrates 125

II Preparation and Chemical Analysis of a Hemo-Ilmenite Standard 132

III Distribution of FeO, Fe203, A1203 and Cr203 in the Lac Tio Orebody 136

1MOSN®~i i " "I~HCMMOAIOMMIEL

VIII

TABLE DES MATIERES

Page

RESUME III INTRODUCTION 1 Chapitre I

GEOLOGIE DE LA REGION DU LAC ALLARD 3 1.1 Introduction, ...,, 3 1.2 Situation .. 3 1.3 Travaux antérierars et histoire de la région 6 1.14 Géographie physique 8

1.5 Géologie généra:.e DO 10

1.5.1 "Série de Grenville" d'apras Retty(1944). 12

1.5.1.1 Quartzite 12 1.5.1.2 Gneiss â hornblende et gneiss â biotite 12 1.5.1..; Gneiss grenatifére 12 1.5.1.4 Roches de la "Série de Grenville" peu communes dans la region 12

1.5.2 "Série: de Morin" d'après Retty (1944) 13 1.5.2.1 Anorthosite 13 1.5.2:.2 Anorthosite renfermant de gros cristaux de pyroxène 14 1.5.2.3 Anorthosite riche en ilménite 14 1.5.2.1+ Dykes d'anorthosite 15

1.5.3 Roches granitiques 15 1.5.11 Diorite, gabbro et métagabbro 15

1.5.5 Pleistocéne et Récent 15 1.6 Géologie utructurale 17 1.7 Géologie 4concmique 18 1.7.1 Introduction 18 1.7.2 Le gisement du Lac Tio 19 1.7.2.1 Minéralogie et chimie générale du

gisement % 22 x..7.2.2 Failles associées au gisement du Lac Tic 26 1.i'.2.3 Prcpri cté magnétique de l'hémo- ilménite du Lac Tio 32

~ b .sesIVIMPIENotnaar011a!IieMIBINr^*434kF/draEidiffilliaâiliilG maintammugatimorstniummeS101LL~Yl+M ismisiminisompammanscon Ix

Page Chapitre II MINERALOGIE DU GISEMENT D'HEMO-ILMENITE DU LAC TIO 35 2.1 Introduction . 35 2.2 Description des minéraux 35 2.2.1 Hémo-ilménite 35 2,.2.1.1 Caractères mégascopiques et micro- scopiques généraux 35 2.2.1.2 Composition chimique de l'hémo- ilménite 39 2.2.1.3 Répartition des éléments mineurs dans les phases ilménite et hématite 41 2.2.1.4 Paramètres et composition de l'ilmcnite et de l'hématite 44 2.2.1.5 Répartition et variation de l'ilménite et de l'hématite dans le gisement 49 2.2.2 Plagioclase 51 2.2.3 Sulfures 54 2.2.3.1 Distribution générale 54 2.2.3.2 Chimie des sulfures 56 2.2.4 Spinelle 57 2.2.5 Magnétite 61 2.2.6 Rutile et anatase . 6' 2.2.7 Chlorite et biotit(1 6ti 2.2.8 Apatite, corindon et zircon 71 2.2.9 Hypersthéae et calcite 75 2.3 Résumé minéralogique 75 Chapitre III GÉOCHIMIE DES HEMO-ILMENIT.ES DU GISEMENT DU LAC TIO 80 3.]. Introduction ... 80 3.2 Choix et préparation des échantillons 80 3.3 méthodes d'analyse et préparation d'un étalon d'hémo-ilménite 83 3.4 Chimie des hémo-ilménites dans le gisement 85 3.5 Variations chimiques de l'némo-ilménite dans le gisement s .... , x17 3.6 Correlations entre les éléments des hémo-ilménites 94 3.7 Synopsis de .a chimie de l'hémo-ilménite 103 X

Page

Chapitre IV DIVERS ASPECTS DE LA PETROLOGIE ET DE L'ORIGINE DU GISEMENT DU LAC TIC) 106

4.1 Introduction 106 4.2 Traits métailogéniques du gisement du Lac Tio 106 4.3 Cristallisation et évolution du magma d'hémo- ilménite 109 4.4 Evolution subsolidus de l'hémo-ilménite 114 4.5 Conclusion 118

BIBLIOGRAPHIE 119

REMERCIEMENTS 124

APPENDICES

I Préparation et analyse de 48 concentrés d'hémo- ilménite II Préparation et analyse d'un échantillon type d'hémo-ilménite 132 III Répartition du FeO, Fe203, A1203 et Cr203. dans le gisement 136 XI

LIST OF FIGURES

Page Chapter I

Fi,. 1.1 Windex map showing the location of Lac Allard Area in relation to other anorthosite-gabbro masses in Quebec 14

Fig. 1.2 Aerial photograph showing the open pit workings on the Lac Tio hemo-ilmenite deposit 5 Fig. 1.3 Map indicating the locality of some of the various ilmenite occurrences discovered by Retty in 1941 7 Fig. 1.4 Topographic map of Lac Allard Area 9 Pig. 1.5 Geological map of the Allard Lake Arr3 (in pocket)

Fig. 1.6 Surface outline of Lac Tio mine (Bourret, 19+9) 20 Fig. 1.7 Photographs of hand specimens from the Lac (a,b) Tio hemo-ilmenite deposit 23 Fig. 1.8 .graph relating specific gravity and grade of Lac Tio ore 25 Fig. 1.9 Graph relating the grade of hemo-ilmenite ore with the amount of Si02 and A1203 27

Fig. 1.10 Surface outline of Lac Tio orebody showing the drill holes and the drill sections 28

Fig. 1.11. Strike section of Lac Tio orebody 291

Fig. 1.12 Dip section of Lac Tio orebody 30

Fig. 1.:13 Aeronagnetic mup of. Lac Tio mine 33 Fig. 1.14 Aeromagnetic profile of Lac Tio hemo-ilmenite orebody 34 Chapter II •

Fig. 2.1 Polished section of an hemo-ilmenite crystal cut parallel to its c-axis 37

XII

Page Fig. 2.2 Polished section of an hemo-ilmenite crystal' tut perpendicular to its c-axis ...... 38 Fig. 2.3 Microphotographs of twinned hemo-ilmenite (a to d) crystals 40 Fig. 2.4 Qualitative electron Probe traverse across an hemo-ilmenite grain 43 Fig. 2.5 Electron probe traverse across an hematite lamella., showing the relative distribution of Fe and Ti in the two main phases of the Lac Tio hemo-ilmenite 145

Fig. 2.6 Lindsley's curves relating 20 (116) and 20 (024) FeKal with the composition of hematite- ilmenite solid solutions 46 Fig. 2„7 Trigonal cracking in exsolved hematite phase 49

Fig. 2.8 Molecular percent of ilmenite dissolved in Lac Tio hematite phase 50 Fig„ 2.9 Pyrite and chalcopyrite in Lac Tio ore 55

Fig. 2.10 Photomicrograph showing pleonaste spinel adjoining hemo-ilmenite 59

Fig. 2.11 Grain of green pleonaste as seen in transmitted light 59

Fig. 2.12 Photomicrograph showing spinel invading (a) ilmenite along hematite lamellae 6o

Fig. 2.12 Electron probe "X-ray pictures” showing the (b to d) distribution ,f Al, Ti and Fe in (a) 6o

Fig. 2.13 Spinel of the third variety adjoining an hemo-ilmenite crystal 62

Fig. 2.111 Spinel adjoining hemo-ilmenite. The presence of rutile in the hematite free rim may be seen 62

Fig. 2.15 Typical microphotograph showing magnetite (a) replacing hematite lamellae in demo-ilmenite 64

Fig. 2.15 Secondary magnetite replacing hematite 64 (b)

a s ',Iy , , ~J~Î

XIIï

nage

Fig. 2.15 Primary magnetite adjacent to a pyrite (c) grain 64 Fig. 2.16 Inclusions of rutile in plagioclase 66 Fig. 2.17 Distribution of rutile in hemo-ilmenite 67 (a to d) Fig. 2.18 Distribution k>f anatase in hemo-ilmenite 69 (a,b) Fig. 2.19 Alteration of ilmenite to anatase. Electron (a to d) probe pictures 70 Fig. 2.20 Microphotograph showing chlorite separating hemo-ilmenite and plagioclase 72 Fig. 2.21 Microphotograph showing brown biotite in anorthosite 73 Fig. 2.22 Euhedral corundum included in an hemo- ilmenite crystal 714 Fig. 2.23 Microphotographs of b persthene in (a,b) plagioclase 76 Fig. 2.24 Microphotograph showing calcite inclusions in a plagioclase grain 77 Chapter III Fig. 3.1 Dip section of Lac. Tio orebody 81 Fig. 3.2 Strike section of Lac Tio orebody 82 Fig. 3.3 Percent TiO2 in hemo-ilmenite concentrates of geological section LM (Dip section) .. 88 Fig. 3.4 Percent TiO2 in hemo-ilmenite concentrates of geological section JK (Strike section) 89

Fig. 3.5 Percent Fe in hemo-ilmenite concentrates of geological sect%on LM (Dip section) 90

Fig. 3.6 Percent Fe in demo--ilmenite concentrates of geological section JK (Strike section) .. 91

PP' 4iv

Eat Fig. 3.7 Percent Mg0 in hemo-ilmenite concentrates of geological section LM ;Dip section) 92 Fig. 3.8 Percent Mg0 in hemo-ilmenite concentrates of geological section JK (Strike section) 93 Fig. 3.9 Correlation of Fe/Tî02 with Fe203/Fe0 in analyzed hemo-ilmeni.te concentrates 95 Fig. 3.10 Correlation of Fe0 with Fe203 in analyzed hemo-ilmenite concentrates 96 Fig. 3.11 Correlation of Fe0 with TiO2 in analyzed hemo-ilmenite concentrates 97 Pig. 3.12 Correlation of Fe with Fe203 in analyzed hemo-ilmenite concentrates 98 Fig. 3.13 Correlation of Fe with Fe0 in analyzed hemo-ilmenite concentrates 99 Fig. 3.14 Correlation of Fe203 with TiO2 in analyzed hemo-ilmenite concentrates 100 Fig. 3.15 (104) hematite and ilmenite reflections for samples containing respectively 31.9 and

26.2 percent Fe203 ... 102 Chapter N Fig. 4.1 Solvus curve .for ilmenite-hematite solid (a) solution series 115 Fig. 4.1 Schematic diagram showing the extent of (b) solid solution in the MgTiO3 -, FeTï03 - Fe203 system 115 ÂV

LIST OF TABLES

Page Chapter I

Table ?..l Rock Vormations in the Lac Allard Area 11 Tabla 1.2 Chemical Analysis of Brmzite Crystals ...., 14

Table 1.3 Analyses of Ilmenite from the Lac Allard Area 19 Table 1.4 Chemical Analysis of Lac Tio Ore (87% grade) 21e

Chapter II

Table 2.1 Chemical Composition of Average.Lac Tio Hemo-Ilmenite 41

Table 2.2 Electron Probe Analysis of Unmixed Ilmenite and HematSte Phases 42

Table 2.3 (116) Reflections cf Unmixed Hematite and Il.nenite 47

Table 2.4 Unit Cell Parameters of Unmixed Hematite and Ilmenite :.., 48

Table 2.5 Chemical ComperAtion of Ai orthosi w a from Lac Tio 52 Table 2.6 Distribution of Cu, Ni and Co ir. the Minerals of the Lac Tio Ore 57 Table 2.7 Partial Chemical Analysis of Spinel from Lac Tio Ore 58

Chapter III Table 3.1 Major Element Composition of Hemo-Ilaenite. Standard 81e

Table 3.2 Minor Element Composition of Hemo-Ilmenite Standard 85

Table 3.3 Chemistry of Lac Tio Hemo-Ilmenite 36 ® . WA ~.~~+. ~~

- 1 -

A MINERALOGICAL STUDY OF THE HEMO-ILMENITE ORE FROM LAC TIO , OUEBEC

IPITROI;UCTIO:I

The Lac Tic hemo-ilmenite deposit (Fig. 1.1, 1.2) is located about

25 miles north of Havre St Pierre on the North shore of the St.Lawrence river and represents the largest body of titanium ore of its type now known in the world. Since its discovery in 1946, several reports and studies have been made on the geology, mining and metallurgy of the hemo-ilmenite ore.

During this period however, there has been very little systematic work done on the mineralogy and geochemistry of the ore.

The present work consists of a detailed study of the mineralogy and chemistry of the hemo-ilmenite ore with the aim to characterize as accurately as possible the chemical and mineralogical variations within the orebody and to provide fundamental data on the crystal chemistry of the ore.

A diamond drilling program comprising 56 holes and totalling

33,027 feet was carried out on the Lac Tio hemo-ilmenite deposit during 1966 and 1967. The drilling defined the vertical and horizontal limits of the mineralization and enabled the Quebec Iron and Titanium Corporation (Q.I.T.) to evaluate ore reserves amounting to arproximately 231+ million tons at a

cut-off grade of 70 percent and an average grade of about 86.6 percent.

The geological and chemical logs from the 1966 - 1967 drilling also provided

general information on the nature of the orebody.

The Lac Tio deposit is presently being mined by the Q.I.T. at a

rate of 2.:3 million tons a year. In the past few years, the mining rate

has been increasing rapidly and it has become important to know as accurate-

ay as possible the nature and chemical variations of the ore through the

entire deposit.. Changes in the composition of the ore would have a direct bearing on the composition of the two final products, iron and slag.

Should important chemical or mineralogical variations occur in some parts of the orebod7, their discovery would most likely influence future mining development programs. For these reasons, a detailed study of the chemistry and mineralogy of'a group of diamond drill core samples representing the orebody k?as initiated in order to provide basic data on the mineralogy and chemistry of the ore.

The contents of the thesis is presented into four chapters.

Chapter one is a summary of the geology of the Lac Allard Area. It is

based essentially on all published information to date, as well as various

unpublished reports in company's file. The second chapter deals with the

systematic mineralogy of the hemo-ilmeni•te ore, and constitutes an inventory

of the characteristics, mode of occurrence and association of all the

various minerals encountered to date in the ore. The third chapter is

oncerned with the detailed geochemistry of the hemo-ilmenite and is based

on the results obtained frcm the chemical analyses of some 48 high purity hemo-

1..menite concentrates. The fourth chapter attempts to discuss the genesis

;' the ore in the light of available data on the Lac Tio deposit. The

Piy,tnois used to prepare the hemo-ilmenite concentrates and the chemical'

p.:FAIts obtained on each of these concentrates are given in Appendices I

t :rn at the end of the thesis;. -3 -

CHAPTER I

GEOLOGY OF THE LAC ALLARD AREA

1.1 Introduction .

During the past 30 years, many reports have been published on the geology of the Lac Allard Area and in particular of the Lac Tio hemo- ilmenite deposit. These reports are reviewed in this chapter which aims to summarize the information avai3 ble on the Lac Tio orebody.

More than half of the reports consulted are unpublished and were

obtained from the files of Kennco Explorations Ltd., the New Jersey Zinc Co. and the Quebec Iron and Titanium Corporation (Q.I.T.). The

remaining published information was obtained from a survey of the literature (1).

1.2 Location

The region known as the Lac Allard Area is located in the town-

ship of Parker on the north shore of the St.Lawrence River, some 130 miles

east of Sept-Iles, Quebec. Its general location is shown in Figure 1.1.

The principal deposit of the area, Lac Tio mine (Fig. 1.2), is connected

tc the St . L.=..•wrence seaport, of Havre St-Pierre by a 27-mile railroad.

(1) The bibliographic sources principally consulted are the Bibliography of North American Geology, the Anotated Bibliography of Economic Geology and the Bibliography and Index Exclusive of North America. Fi V i LAC. ALLARD RE AREA r . PIERRE

• SORÉL MONTREA~~

c~ P

100 MI. NEW YORK 200 KM

Figure 1.1 Index map showing the location of Lac Allard Area in relation to other anorthosite-gabbro masses in Quebec.

imeat iliG IINgliali 5

Figure 1.2 Aerial photograph showing the open, pit workings

on the Lac Tio hemo-ilmenite deposit. The hemo- ilmenite ore is presently being mined at the rate

of 2.3 million tons a year. After primary crushing

the ore is brought by railroad to the port of

Havre St-Pierre where it is loaded in boats and

shipped to the Sorel Plant. _6

1.3 Previous Work and History of the Area

The presence of hemo-ilmenite in the Lac Allard Area was first reported by J.A. Retty for the Quebec Department of Mines following a reconnaissance shore-line geological survey in 1941. The ensuing report

(Retty, 1944) describes the occurrence of a number of small hemo-ilmenite deposit3 along the shores of lac Allard, lac Petit Pas, lac Puyjalon and lac Bat du Diable (Fig. 1.3). Lac Bat du Diable which does not appear in Figure 1.3 is located approximately 4 miles southwest of lac Allard. The showings discovered by Retty were subseçuently staked by Toronto and Montreal interests and a certain amount of exploration work was carried out. Kennco Explorations Limited (subsidiary of Kennecott

Copper) optioned the claim groups in 1945 and initiated in the summer of 1946 a detailed exploration program in the vicinity of the occurrences described by Retty in the hope of finding larger orebodies. This work resulted in the discovery of a num`fer of hemo-ilmenite deposits, among which was the large orebody of Lac Tio'11 (Hammond, 1952).

(1) The Lac Tio deposit was actually discovered on June 10, 1946, by two students from Laval University employed on the Kennco exploration party. Traversing from lac Petit Pas southward towards lac Puyjalon, the two students recorded strong negative dip needles readings at a point approximately mile from the origin of their traverse. Outcrops of massive hemo- ilmenite were observed a short distance from this magnetically anomalous area. Going further south they reached a stream which had cut through the overburden. The stream bed was underlain by glistering black massive hemo- ilmenite. Further south on their traverse they came upon a small lake approximately 1,300 feet long and 100 feet wide. This lake was later named Lac Tio. A very steep cliff rises on the west side of Lac Tio. Traveling along the east shore of this lake, the students were confronted scarcely 100 feet across on the opposite shore, with a virtual mountain ofmassive hemo-ilmenite. vommisiessaimommlininilEXIMENIERIENIMINI

L.PETIT PAS ~

v1} L. ALLAR D

f L . PUYJALON

a 0 1LMENÎTE OCCURtNCES SCALE: 2 MILES TO I INCH OR 1:126,720 0 I 2 3 4 5 6 iom~u~------iki MILES

Figure 1.3 Map indicating the locality of some of the various ilmeni:te occurrences discovered by Retty in 1941 (Retty, 1944) . 8

Fo'.lowing this exploration program and the successful discovery

of the Lac Tio the remaining anorthoaite area west of Lac Allard was explored ?n 1947 using an airborne magnetometer survey. This survey

did not reveal new deposits; however,st:.ong anomalies were recorded over

all known majcr déposits (Bourret, 1949). 'While exploration was being carried out, the New Jersey Zinc

Co. vas experimenting on a process for producing iron and titanium bearing

:lag from hemo-ilmenite ore by electric smelting. The Quebec Iron and

Titanium Cn poration (Q.I.T.) was incorporated in 1948 for developing and

operating the mine and erecting a smelter to prodess the ore.

The 27 mile long railway that links the Lac Tic deposit to the

port of Havre St-Pierre, the dock facilities at Havre St-Pierre, the Smelting Plant and receiving dock facilities at Sorel were built in 1948

and 1949.

The mining started in 1950 at the Grader orebody, now idle, but

from which over 200,000 tons of ore was extracted. Sine:. then Q.I.T. has

been ^fining the Lac Tio hemo-ilrrsenite deposit.

( 1.4 rlyalaa. GeGe°. ai,fly Along the coast, and north of tue westwa: d flowing portion of

the Romaine River, is a flat coastal plain known as the lowlands (Fig. 1.4).

The lowlands are underlain by flat-lying Paleozoic limestones and consist of open muskeg dotted with many shallow lakes and ponds. The ground between

the Romaine and Puyjaton Rivers is flat and sandy and represents parts of

an old marine terrace. -9-

uin Chan 'ii; ~~/• iaure St-Pierre r-t• 'Havre- St-Pierre :• --•...~._ . . - ••••••, EsWmo ~: v~ . ~ . \, Sea Cow rilobit: t:~j:::?'.;; ;`;~_,,,._.7i.. •a•~;~~ Bav Island / Island f{[ty ..• ~ • . t~~.. ~ . • Gree n, , t Fright I P t 1T3 .Fi ay: . !~ 1 Wnlrus I 'K I/ B~ Gult i < • • ,,.,t a ,~LISt•Chgrlr— s`-^'~ I msannarsomonninggi amennsis s on

0 5 1G _~_...p _~asll^n • 5=14 r78giFar MILES Figure 1.4 Topographic map cf Lac Allard Area. (Map 12 L, Mines and Technical Surveys, Ottawa.) -10 -

Approximately 3 miles from the coast, the terrain rises rapidly to form the uplands. Viewed in a general way, the surface has the appear- ance of an ancient peneplain with the horizon presenting a general uniformity of summits in all directions. In detail, however, the surface is a much dissected platen with precipitous cliff faces and well entrenched valleys. At Lac Allard, the highest summits reach 1,300 feet above sea level. The maximum relief is approximately 800 feet; the average relief is between 200 and 300 feet. The uplands are underlain by igneous and metamorphic rocks of the Grenvflle Province.

Glacial erosion has been an important factor in shaping the present topography. The larger lakes occupy north-south depressions approximately parallel to the direction of ice movement. Many small lakes lie perched in irregular depref,sions at higher elevations and the secondary drainage sy.-gem has been disorganized to a large extent.

The area is drained by the Romaine River system which head lies near the Quebec Labrador boundary. The Romaine flows in a well entrenched valley, with numerous rapids and falls.

Throughout the uplands, a thin cover of boulders and soil rests on bedrock and supports a stunted growth of spruce, balsas and pine. Many large glacial erratic., most of granitic in nature lie strewn about the surface.

1.5 General Geoloçy

The consolidated rocks of the Lac Allard Area are of Precambrian

age and comprise a series cf metamorphic and igneous rocks that belong

to the Grenville Province (Fig. 1.5, in pocket). The formations that

underlie the area are summarized in Table 1.1. Table 1.1

Rock Formations in the Lac Allard Area (Retty. 1941 )

Pleistocene and Clay, sand, gravel Recent • Diabase Lamprophyre Gabbro, metagabbro Intrusive Porphyritic granite, horn- rocks blende granite, pegmatite

Precambrian "Morin Series" Arcrthozitic dykes Grenville of Retty, 1944 Anorthosite with coarse pyroxene Province crystals (Hargraves, 1962) Anorthosite, anorthositic gabbro, £_narthnsite rich in ilmenite.

"Grenville G;uartzito. quartz-biotin. Metasedimen- Series" of F ;aes, quartz-hornolende tary rocks Retty, 1944 rne .ss, garnetiferous gneiss, amphibolite, garnetiferc;ur: graphite schist, injection gneiss 12

1.5.1 "Grenville Series" of Retty (1944

Rocks of the "Grenville Series" are represented by quartzites,

quartz-biotite gneiss, quartz-hornblende gneiss, garnetiferous gneiss,

and small patches o: amphibolite and garnetiferous graphite schist. These

rocks occur abundantly along the Romaine River between the First East

branch and the Second East branch. Numerous outcrops are also found on the

shores of Forget lake and in the adjoining area to the east. 1.5.1.1 Quartzite

The quartzites are common in the region of Lac Allard. The rock is ordinarily composed of small white and vitreous grains of quartz and

small proportions of biotite, magnetite, and in some places disseminated

garnet. 1.5.1.2 Hornblende Gneiss and Biotite Gneiss

Well banded hornblende gneiss and biotite gneiss are also abundant

in the region of Lac Allard. They are composed principally of quartz, horn-

blende, biotite, orthoclase and plagioclase in varying proportions.

Apatite, zircon, magnetite and graphite are the usual accessory minerals

found in the gneisses.

1.5.1.3 Garnetiferousneir G A large part of the "Grenville gneiss" in the Lac Allard region

contains in afiditiou to quartz, some 15 to 20 percent garnet with small

quantities of albite, graphite and biotite. This variety of gneiss is also rich in hornblende. 1.5.1.4 Less Common Rocks of the "Grenville Series" in the Area

Among the less common rocks observed by Rates 5-n the region,

are graphitic garnetiferous schists, greywackes, amphibolites, migma-

tites and injection gneisses. 13

1.5.2 "Morin Series" of Retty (1944),

The most important lithological unit in the Lac Allard region

(Fig. 1.5, in pocket) is anorthosite and related rocks. They were grouped as "Morin Series" by Retty op. cit. and comprise anorthosite and associated • rocks such as anorthositic gabbros and anorthositic dykes. As shown in Fig. 1.5 (in pocket) in the Lac Allard Area, these rocks extend for more than 70 miles in the southwest direction and form a zone approxim.tely

20 to 30 miles wide. 1.5.2.1 Anorthosite

Anorthosite is the major rock type in the vicinity of Lac AL:lard.

As a rule, it is massive, coarse-grained and contains 95 percent or more plagioclase. In fresh exposure, it varies in color from pale gray to pink to somewhat resinous green whei:it contains more than 5 percent ferromagnesian minerals. In weathered outcrops, the anorthosite is usually gray to chalky white. The equig:aniiar varieties of anorthosite have grains sizes that range from 3 to 6 mm and is characterized by sporadic coarse plagioclase phenocrysts 2 to 35 cm long. The phenocrysts are similar in composition to plagioclase of the enclosing matrix (Hargraves, 1962).

In thin section, the texture of the anorthosite varies from hypidiomorphic to allotriomorphic'granular, and the plagioclase grains

(An 40-52) range from 3mm to 12mn in size. Approximately half the 25 thin sections examined by Hargraves (1962) showed evidence of cataclasis as indicated by scattered relics of larger crystals exhibiting undulatory extinctions, bent twin lamellae and fractured margins. The finer-grained

material surrounding the deformed fragments and locally constituting the entire rock, is anhedral and displays intricately sutured grain bound-

aries, suggesting recrystallization of crushed material. -11+-

1.5.2.2 Anoruhosite with Coarse Pyroxene Crystals

Hargraves (1962) noted in several locations,zones of anorthosite characterized by coarse crystals or cloth of crystals of greenish bronzite.

A chemical analysis of typical pure bronzite, separated from samples collected at Lac Tio is given in Table 1.2

Table 1.2

Chemical Analysis of Bronzite Crystals (Hargraves. 1962),

SiO2 51.81 Na20 0.01 A120 2.80 K20 0.00 Fe203 2.09 H0♦ 0.07 ~ Fe0 17.27 H20 0.03 MgQ 21+.18 TiO 0.52 2 CaO 0.83 Mn0 0.29 Total 99.90 Calculated formula En 69 Fs 31

1.5.2.3 Ilmenite Rich Anorthosite The ilmenite rich anorthosite (oxide rich norite of Hargraves,

1962) is medium-grained seed slightly foliated or gneissic. Tie essential constituents of the rock, in paragenetic order, are plagioclase, pyroxene, a, atite and oxide. Despite variation in the relative proportion of these constituents, the mafic fraction rarely constitutes less than 50 percent by weight of the, rock. Sulfide, largely pyrite with minor pyrrhotite are constant accessories, and secondary biotite is sporadically distributed.

A study of thin and polished sections of the oxide rich noriti.c anorthosite (Hargrave, 1962) reveals that it contains the follovbug 15

mineralogy :

Magnetite 10% Hemo-ilmenite 10% Pyrite with minor 2% pyrrhotite Plagioclase 30-40% Hypersthene 20% Augite 5-10% Biotite 2-3% Spinel Traces Apatite 5-10% 1.5.2.4 Anorthosite Dykes

Retty (1944) describes the occurrence of three anorthositic

dykes cutting the anorthosite massif. These dykes generally have a composition identical to that of the anortht.site itself. 1.5.3 Granitic Rocks /1 The rocks are usually coarse-grained and exhibit a porphyritic

texture. In those rocks, the quartz is ordinarily opalescent and the /1 mafic minerals, hornblende and biotite, are visible to the naked eye.

In thin section, apatite, zircon and magnetite can be recognized as

accessory minerals. Retty (1944) has noticed that the rock is locally poor in quartz

and could be more appropriately named syenite.

1.5.'4Dio r ite,, Gabbro and Metagabbro,

Diorite, gabbro and metagabbro have also been noted in the Lac Allard Area (Betty, 1944). Since these rocks are not very common in the

re:pion, they will not be discussed furti:er in the thesis. 1.5.5 Pleistocene and Recent In the lowlands, the traces left by the glaciation have been

washed by the invarion of the Champlain Sea and covered by sediments.

Sand, cls;y and gravel are the win constituents of the marine deposit. - 16 -

In the Lac Allard region, the U-shaped valley of the Northeast

Romaine River constitutes the main evidence of glaciation. The sand and gravel deposits along that river are considered to be of glacial origin. Some glacial striations along the shores of Forget Lake indicate that the movement of the ice sheet was from north to south. However, in the vicinity of the Bernard and Northeast Romaine Rivers the striations seem to indicate a south-west movement. 1.6 Structural Geol

There is much evidence that the area has been subjected to large scale structural disturbances over long periods, as indicated by the highly contorted and metamorphosed nature of the Grenville type rocks and the strong fault and joint systems developed within the aaorthosites (Bourret, 1949). In the vicinity of Lac Allard, the anorthosite is text by numerous steeply dipping to vertical joints and faults. They strike north or northeast and represent faulting of the normal type in which the hanging wall block has moved down relative to the footwall block. These features are everywhere apparent in the topography, giving rise to preèipitous cliff faces. In many instances, they appear

as a series of steplike structures along the hill slopes.

Some of the major faults have been traced for several miles, and Borne continue without appreciable change in strike beyond the

anortt.osite body and into the surrounding granite. These fractures are

open and obviously younger than all of the Precambrian rocks of the

area. It is usually impossible to determine the relative displa-

cement in an intrusive rock of uniform composition such as anorteosite.

However, one major fault has been studied in detail in the vicie ity

of the Lac Tio deposit, where it appears to have been an important factor

in the preservation of the main orebody. Detailed exploration has shown that the erebody is in the form of a large, tabular, relatively flat- lying mass. It can oe reasonably ass',.med that the attitude of the ore

was the same at the time of deposition. A north-south fault, with a „teep

dip to the east, cuts through the middle of the deposit and has moved the east side of the orebody downward, a vertical distance of approximately

300 .feet. There is no apparent horizontal movement. As a result of this fault, the ore in the east part of the deposit was preserved from erosion and Pleistocene glaciation.

1.7 Economic Geology

1.7.1 Introduction The economic interest of the Lac Allard region is primarily centered on the deposits of ilmenite it contains. Although Retty (1944) noted the occurrence of chalcopyrite mineralization in paragneisses in at least six localities, he principally emphasized the potential of the region for possible ilmenite deposits. His discovery of several ilmenite deposits along the shores of Lac Bat-du-Diable, Lac Allard, Lac Petit Pas' and Lac Puyjalon (Fig. 1.3) was a key factor that initiated the subsequent development of the region. The largest deposit of the area, the Lac Tio deposit was discovered in 1746 following exploration work undertaken by

Kennco Exploration Ltd. Other deposits of less importance were also out- lined by this work; such is for instance the Grader Lake deposit from wh:+.r 1 200,000 tons of ore were extracted in the period of 1950-51.

"11 of the ilmenite deposits of the area are associated with anotthositic rocks and probably have closely related origins. They may be classified structurally (Hammond, 1952) into thr:e types on the basis of attitude and shape of the oxide masses; these are, flat'-lying tabular bodies of large areal extent (Lac Tio deposits and satellites), steeply dipping dyke-like bodies (Puyjalon deposit) and lenticular masses irregular in shape. There ere in the Lac Allard area six ilmenite deposits which respectively contain a million tons or mc.r -. 19 - largest and most important is the Lac Tio deposit which is presently mined at a ratc of 2.3 million tons per year. The deposits of the Lac Allard region contain ilmenites of similar composition. The original analyses of the ilmenite phase of the ore from six deposits discovered by Retty in 1941 are presented in Table 1.3. Their high iron content relative to TiO2, similar to that of the Lac Tio deposit, indicates that they are ilmenite-hematite exsolution mixtures and are appropriately referred to as hemo-ilmenites (Buddington and Lirisley, 1964). Table 1.3 palyse:, of Ilmenite from the Lac Allard Area (after Rett- . 1944)

(5)* (1) (2) (3) (4) (6) Fe 45.01 41.18 45.08 43.33 43.41 43.64 TiO2 32.24 36.00 35.98 35.89 38.14 37.79 Si02 1.36 2.57 1.78 0.96 0.87 1.42 P - - - - 0.05 - S 0.14 0.47 0.16 0.16 0.16 0.11 V 0.02 0.08 0.03 0.03 0.03 0.19

1.7.2 Me Lac Tic Dep o it The Lac Tio deposit is an extensive body of hemo-ilmenite lying roughly half way between Lac Puyjalon and Lac Allard (Fig. 1.5, in pocket) approximately 23 miles northeast of Havre St-Pierre on the; north shore of theSt.Lawrence River. As determined from surface exposures and diamond drilling, the depo,it is 3600 feet long and 3400 feet wide and occupies an area of 134 acres (Fig. 1.6). The maximum elongation of the deposit

' These numbers refer to the original locality number in Retty (1910:; (See Fig. 1.3). - 20 -

LAC GRONDIN

NORTHWEST ORE BODY

:. GISEMENT .. MAIN ORE BODY NORD-OUEST GISEMEN'i' PRINCIPAL „

LAC TIO

CLIFF ORE BODY

GISEMENT CLIFF

0 500 10~0 1500 LAC ANO EF DS ~ i 1 0 250 500 M

Fig. 1.6 Surface outiille of Lac Tic) mine (Bour•~et, 1912) - 21 -

lies almost due north, however, its plan expression is irregular with large lobes of ore extending east and west. Thr:re are also wide variations of elevation in the area underlain by massive hemo-ilmenite. A compara- tively level valley occupies the central part of the deposit and extends to the snithern end of Lac Tio. On the west side of this valley the terrain rises rapidly and reaches an elevation as high as 140 feet above the valley floor. For convenience the Lac Tio deposit is generally considered by the Mine personnel as consisting; of three parts (Fig. 1.6); the Main orebody, the Northwest and the Cliff orebodies. Although the Cliff orebody is separated from the Northwest orebody by a large block of barren anorthosite, it is undoubtedly closely related to it in origin.

The Main orebody is by far the most important part of the deposit with respect to size and thickness. South of Lac Grondin it occupies a large crudely recta:irular area from which a smaller triangular portion protrudes and extends south along the east side of Lac Tic). The western edge of the Main orebody abuts against a north-south trending and steeply dipping fault along which the eastern block has moved downward relative to the western block. The Northwest or:-oody which lies on the west side of this fault is a thin flat-lying body from 25 ;o 200 feet thick and dips gently to the east. The Cliff orebody (Fig. 1.6) is a broad, flat-lying, tabular mass of hemo-ilmenite that rises sharply above the western shore of Lac

Tio. It is crudely elliptical in plan expression and measures 1240 feet in a north-south direction and 740 feet in the east-west direction. The -22- average thickness of the crebody is approximately 200 feet. The eastern part of the orebody is well exposed along the shore of Lac Tio. The orebody has a relatively uniform floor in sharp contact with the underlying anorthosite and dips gently to the east. Drilling,on the west side of Lac

Tio,indicates that the ore extends flatly under the anorthosite wherA it thins rapidly and pinches out. The larger part of the ore of the Lac Tio deposit is concentrated in the Main orebody. Blocks and/or inclusions of anorthosite, as well as zones of disseminated hemo-ilmenite are present throughout the deposit. The blocks of anorthosite vary greatly in size, shape and orientation. They are presumed to represent blocks of country rock engulfed or included in the ore during its emplacement. The zones of disbeminated hemo- ilmenite commonly occur as subhorizontal bands within the massive hemo ilmenite.

1.7.2.1 General Mineralo•. and Chemist of the Lac Tio Deposit

Although the Lac Tio or more commonly the Lac Allard ore is

usually referred to as ilmenite in the literature,it actually consists of a microscopic intergrowth of hematite in ilmenite. Such ilmenites are

called hemo-ilmenites (Buddington and Lindsley, 1964). The ore is a

dense, black, mostly coarse-grained aggregate of thick tabular crystals

of hemo-ilmenite (Fig. 1.7a, b). The specific gravity of the material

classified as ore ranges from 4.46 to 4.9. The relation between grade(1) and specific gravity of the ore is shown in Fig. 1.8. Plagioclase in

(1) Grade is defined as t'le sum of FeO, Fe2C3 and Ti02. -23-

(a)

Pia- 1-7P-- t Photographs of band specimens from the Lac °iic hemo-ilmenite deposit : (a) X 1/2 (b) X 1. - 21. -

amounts varying from 3 to 12% and accessory amounts of pyrite, sninel,

biotite, magnetite and hypersthene are generally found in the ore. Chalco-

pyrite, millerite, rutile, zircon, chlorite, corundum and anatase are

also present in very small amounts. Detailed information on the nature

and occurrence of these minerals are given in Chapter II.

The ore generally mined by G.I.T. has a grade of 87%. A

typical analysis of this ore is given in Table 1.4.

Table 1.4

Cheniiccal Anal of Trac Tio Ore (87'4 Grade)

...~~~?re i Rht `'1 Ti02 34.2 Idn0 0.16 Fe0 27.5 S 0.3 Fe203 25.2 PIa20 and K20 0.35 Si02 4.3 P205 0.015 A1203 3.5 Cu 0.006 CaO 0.0 Ni 0.026 i+iRO 3.1 Ga 0.003 Cr203 0.10 Co 0.015 V205 0.41

Lister (1066) has studied the chemical variations in the Lac

Tio orebody. The results of his work indicate that there is no regular va-

riation in the Fe/Ti02 ratio in the orebody. However, localized chemical

variations were observed. In the .massive hemo-ilmenite portion of the

deposit, the amount of Cr and V decreases upwards while that of Mg increases.

These trends would not seem to be present in the eastern or layered sections

of the ore sheet. The Mn content cf the entire deposit is unusually low.

The chemical composition of the ;i*ero-ilmenite crystals corresponds arrnro-

ximately to 30 percent hematite acid 70 Percent magnesian ilmenite. The

lowest amounts of Mg and the highest amounts of (Fe 4* Ti) were found in

ar.B IAt.ta.e..lmmo wn..wlwa. a.l c.alwalv aua ~s~ • 5.0

4.8 • • • • ~• —, 4.6 • • ~ •• • 4.4

42 • 42 • 4.0 4.0 M

3.8

U II 3.6 &6 V w a N 3.4 --' 3.4

3.2 3.2

à0 3Si

I 1 . i ~ .._.~,.._~ . ! ~ i 1 ~ ___~__ 50 60 70 80 90 100 GRADE •0'' ORE ( % Fe203 + % Fe0 + T102 )

Fig. 1.R Graph relating s(cific gravity And grade of liac Tic) ore (New :Jersey Zinc) . iiiimminiormimammumium umummeimaxr.ans•sr. ~~•. ~~~~m~• tlp~arr.~ -26- hemo-ilmenites from the upper part of the layered section of the sheet

(Lister, op. cit.).

Compared with the hemo-ilmenite from the deposit, the hemo- ilmenite from the anorthosite host rock has a lower minor element content with the exception of manganese.

The relations between grade and the amoun'. of Si02 and A1203 in Lac Tio ore is shown in Fig. 1.9. It is interesting to note that the trend for the SiO 2 values extrapolates to zero at the maximum grade ore while the alumina values extrapolate to about one percent. This is interpreted as indicating that the pla?ioclase (silicate) content of high grade ore may approach zero but its spinel (aluminate) content may be as high as 2%.

Figure 1.10 shows a plan view of the Lac Tio orebody where the diamond drill holes and sections are indicated. The numbers (e.g. T-91-6) correspond to the locations of the holes drilled in the summers of 1966 and 1967. Figure 1.11 is a strike section corresponding to the line J-K on Figure 1.10. Figure 1.12 is a dip section corresponding to the line L-M on Figure 1.10. These sections are from Lister (1968).

1.7.2.2 Faulting of the Lac Tio Orebody Three faults trarsect the orebody in the mine area (Lister,

1968). The most important fault forms the boundary between the Main and the Northwest orebodies (Fig.l.6).Scissor-like movement along this plane would appear to have raised the west block approximately 300 feet at the north end of the orebody (Hammond, 1952). The displacement along this fault decreases towards the south and the fault seems to terminate within the Cliff orebody. - 27-

14 on) 12 412 03

10 o

M 8 0 N

60 70 80 90 100

GRADE OF ORE

Fig. 1.9 Graph relating the grade of hemo-ilmenite ore with the amount of SiO2 and Al20. (New Jersey Zinc).

~ :: .;: •ï : :~. k• 4T- 99-8 ~'"'I+ :. a~ (1' LAC 0,000 N f::::::: ; : ~ I ~::: .~~` .....17.,.....-. GRONDÎN 1Q '• ?~ ~~.:' A :: •: • .§7-9• 97 '+: %::; : 7-1 ••T-97-2,.~.. _ ~ 9y-5:, :;~ ~. T- ~'• T 9 •~;. : T-97-g ~ ::'Y- LEGEND F:~'•: ..~~ I.;:::•' • \ :.•:4~.. ::::::• .. • h•-9T~~ ï~ ••:•:-».....:::. :9 T-95••4 /1-95-6 95.3 T-95-1 T-95-2 %XT- --- T-95-5 -•- - n--0 - --+6rtir%• --- • - - • - 0 .~N~ MORE THAN 70% ILMENITE T-92-8 % ` z `,~'i1r.r ILMENITE ( 30-70 %) S \ .`` !:'•• 15;4:? ]Y•~:~,~' T- 901-7 i:::::::: .....\.... ST.-9 1-1 T-91~ '~•'-T91 T-9~-6 'i;~~r91-5 DRILL HOLE ( 1967) i:::::,;:: ~• ~_ _ •- ... • >~ ; ~:v};,- • — ,~,~ f:u 0 • a~..~e • DRILL HOLE( 1966) 9 Oo~ NORTHWEST ~ st...... •,~ ~ i ;:~.~. ; .1_~r~~ ' OREBODY ....4...v57:„....______. .ti.' DRILL SECTION {i~P` \ I .~1F6.. ....,, T- 87-11 T- 87-10 i T-87-6~~:r,T-87a T-87-3 ~*~`T-87-1 0 0 T-87-9 T-87-5 . •T•-- • r----,.~ • ._ • •~-,i,Wr ;,,~. .. • — - _— • _ -~st±rr~~3~- 0 S ...... \ / a. a. :: : :•: ~~// ~~;-~`43 ...*:•:::•:•:•;:?::;::.r ..1.:.:::.: ::,.. ~ MA I N ~ OR E:t;?•B~O~ -%!;:7~ 1-43 -7 :.•:' jiv '' ::. ,'~~'`% _...2.;.:.~'' T 8.3-2.... _ T-83-I T Q3'~ ~~• k•`<`='' T-83- 4;~;;J 'f'• O T ', 0 ---s~;~ --~ ,`~••-- - ,L `` •'~' `\:~S~ ~_::~:• !~_• I L•~/ \°•' ; T-79-3 T-79-1 i>1- 6 1-79-7 • 9-5 —Q—. ~ -T-79-2 ~ T ~ ..~ T-75-3 T-75-1 ~•/'•T~~~ T-75-2 . T-75-5 0 -~f ~•• •• F'' CLIFF • + ~~'~~y:!!•T 1 •~'~~ ~~ `:•'~•~•:~ OREBODY TI-13;~. T-71-7 '• ;;r; •..r,^..~'i~~ ~~• - ••~•e_1:1iI:,;r1 e ':îr ~ ~ •;:;~~••• • :; .,~,..::',. T:~::::, • ~'~:_:.E• ' • . Y,.. ~ T-67-2:: ~~e~h-6 T1 ~•i;~r • . • DDH Pt1 AN ~ ~:: : ~ SCALE I = 600'

... • . . ~ T 64-1 •

000N

Fig.. 1.10 Surface outline of Lac Tiso orebody showing the drill holes and the drill sections (Lister, 19(3).

11111E111111=1121111111111111

~ I

~ -- —? ••••~ ~ •V•••.. —.,_--- .r ^r•~ ~ —..-3 ~1 _.. T-64-I T~7 2 T-71-8 t-- - '~ — T--91 4—.. —.,_ —. ---c<:::: :::: — -- ..... `► --T•75-2 T-79 fi 7.313-1 --., F95-9 .~ ~, _•~ :I'„•~PRESENT SURFACÉ T-67—E • 1..GRON 1N . . . . : .t•...... _ . . .LS~k - _ i•`itYi . •.T r7i' ~.-Ji• Vû .. ~ . — ~ / .~ :~I : 500 v . .,. . i 1 1 _ ;;v`•i / • ï 7 ,-.: ' I 1 ~~~~ ~ : •. ,.'-:: . % • ; f / ti\'t / / -""..14::. .- a+ 1~ p I - 1 / 1 . t i / t / .. ~ •~ 1 t . / 1 t \i. \ . 1 / ,I t'/ \ ~ • / - \ ~~ i ~ tl; ~ / / t ! ~/ . / / \ t \ _ '1 ~ \ ; ; f / I , f ~ 1;~:; / 1 ~ , e l. t it / / 1 1 t ~ :;{•: ✓ i~ / 1 • • / --.4.':'."'v. / ! I I 1' \/ 1 ti t/ `/ 1 1. t ~`L•ü ~~' .t:iYé~'~' ~'Ÿ / \.~1~ / . I` \_ '' t I ' I / 1 1 .... t \ / 1 ~ • /. '/ / 1~ J/ , I/ I \~ 1 ! J I~ .- t1 ~ / /~ - — \•i 1f \ . ~f ♦~ `/ . I !V 1 1 —• t• .. ~ ~ — 1 ~ I ~ I I ..t 1-500 LEGEND

> 70 % HEMO-ILMENITE

30-70 % HEMO- ILMENITE LAC TIO ILMENITE DEPOSIT ANORTHOSITE SCALE 1"= 600' LAKES DATA BY G.E. LISTER

rig. 1-11 Strike ;lecr' ,ion of Lac Tio orebody (Lis G r, 1968).

intanaminmenseartilimmilimill111101111MIAMMILMOMEIBRAMMEISIIIIIIIIII0111k INEVNIIIMENE

^ ~_ I %RESEN.F. .- 1. ^ ^ T-92-8 r x iv::;:::~::;: , , S(/RFACE ~ v ,~:.; ::::;:: Tw:~t::::;::: T797 PRESENT SURFACE v~~` ..:•:•:•:::"...‘ T79-6 T-87-9 T-833 T-83-4 L r• V . 7 ( < 7 V• r RISEN 500 > v V V 500 < ' V % < ç -7 1 < - ^ L A L.< '::::~ : _a..~•~,;~ :;;::~~:: ~ , ~;,• , ~~:y~~::r ~ A n ~. ~`;•,';• i:r`, . SEA LEVEL SEA LEVEL

500

Î`. „..:~..::~ •: .~ . :Ï •~s.►,. +: :s .:~+.+: R L ‘,0 T• G d t , J J J ., n

LEGEND

C:1 > 70 % HEMO-ILMENITE

30'70 % HEMO' I LMENÎTE LAC TÎ0 ILMENITE DEPOSIT ANORTHOSITE am SCALE I": 6001 DATA BY B.F. LISTER

Fig. 1.12 Dip section of Lac Tio orebody (Lister. 1968).

r'9>sv>IisRismiF3misi i~~~ lint=Îi1111 :1?: 11111111111111111101111111111111111W111111111WMANIEMENIMEW

- 31 -

Another fault extends southward from the southern tip of Lac

Grondin. At Lac Grondin, scissor-like movement along this plane has raised the east block less than 100 feet above the west block. Displace- ment along this fault decreases further to the south; no displacement is apparent at a distance o2' approximately 1000 feet from Lac Grondin.

*The third fault was mapped in the pit, where it extends north- ward from the west side of Lac Tio. Displacement of the base of the orebody along this fault seems to be minor. The southern extension of this fault is thought to separate the Cliff orebody from the Main orebody

(Lister, op. cit.). Chloritization over widths of a few inches is generally evident where steep faults cut the orebody. The feldspar and faulted anorthosite has been bleached, reddenet., saussuritized or chloritized. In very few cases, minor hydrothermal leaching of iron from hemo-ilmenite along the faults, has given rise to zones of brown, r>>tilized hemo-ilmenite for width: of a few inches (Lister, 1968).

These faults are part of strong north and northeast trending linear features, that are evident in the field and on aerial photograrns of the area (Lister, 1966). Topographic offsets along these lineaments suggest that these are faults with relatively minor vertical displacement, probably less than 50 feet in most cases (Lister, 1968). These faults together with the three faults described, would appear to be àensional features related to post-ore• intrusion relaxation and por.Fibly related in part to the cooling of the hemo-ilmenite body (M.ster, 1968) . 1.7.2.3 A'I netic Pronert of the Lac Tio Hemo-Ilmenite

The "magnetic expression" of the Lac Tio orebody soon attracted the interest of geophysicists. Contrary to magnetite-ilmenite orebocli es common to anorthositic terrains which characteristically give rise to strong positive magnetic anomalies, the Lac Tio hemo-ilmenite appears on aero-magnetic nap as a conspicuous "magnetic low". Figure 1.13 is an aeromagnetic map that ewers the Lac Tio area; the surface outline of the orebody has been superimposed on the magnetic data (Hammond, 1952). A magnetic profile (Fig. 1.14) illustrates the strong negative anomaly associated with the Lac Tio orebody. The massive hemo-ilmenite deposit gives rise to sharply defined negative anoaal4es.

Their magnetic intensity lies some 3500 gammas below the average magnetic intensity of the surrounding rocks. The strong negative anomalies are believed to be the result of negative polarization of the orebody itself

(Carmichael, 1961). A detailed study cf some hemo-ilmenite specimens by Carmichael (1959) has shown that the remanent magnetization is mainly due to the hematite lamellae. GRONDIN LAKE

-'C

50~ Ip00 1,5J ANO ~E~.m 'om.+u~ FEET LAKE

LEGEND :

o o oo , o SURFACE OUTLINE OF LAC TiO MINE.

AEROMAGNETIC CONTOUR—INTERVAL 500 GAMMAS. Fig. 1.13 Aeromagnetic map of Lac Tio Mine (Hammond, 1952). 4•11111•• gammas

1500

1000

500 o

—500

—1000 liMENITE-HEMATITE An —1500 ANORTHOSITE

2000—

1200 FT

400 FT 1 0 1 2 3 MI. I 0 2 3 4 5 KM 1 • 411/••••••.• ••••••P

Fig. 1.14 Aeromgmetic profile of Lac Tio hemo-ilmenite oreboilz (Botrret, 1949). - 35 -

CHAPTER II

MINERALOGY OF THE LAC TLO 1iEMO-IL ENITE DEPOSIT

2.1 Introduction

The Princiral minerals identified to date in the Lac Tio hemo- ilmenite ore-are hemo-ilmenite and gangue minerals mainly represented by plagioclase and accessory or trace quantities of sulphides, sninel, magnetite, rutile, anatase, chlorite, biotite, apatite, corundum, zircon, hynersthene and calcite. T'ne aim of this chapter is to describe these minerals, placing special emphasis on their composition, occurrence and association.

This part of the study is based principally on the results of microscopic examination of polished sections and polished thin sections obtained from approximately 40 snecimens. X-Ray diffraction, X-Ray fluorescence and electron microprobe analyses were used to identify the minerals and determine their compositions. The occurrence and characteristics of the various minerals are illustrated with the hein of micro- rhotograrhs. Electron microprobe traverses and "X-ray Pictures" are also used for illustrating the distribution of elements within particular mineral chases.

2.2 Description of Minerais

2.2.1 Heuo-ilrnenitr,

2.2.1.1 General Megascoric and Microscopic Characteristics

Typical Lac Tio ore consists of a dense aggregate of coarse-

grained black hemo-ilmenite (Fir. 1.7a, b). Monomineralic specimens have - 3E - a specific gravity of 4.8. The hemo-ilmenite crystals are tabular or pellet shape and lie oriented roughly parallel to the attitude of the ore sheet (Hargraves, 1959). Some hemo-ilmenite is also found disseminated in the surrounding anorthosite rock. A large mass of disseminated hemo-ilmenite in anorthosite occupies the northeastern part of the deposit'. Under the microscope,the mineral is seen to consist of a regular microscopic lamellar intergrowth of ilmenite and hematite. Two group,3 of hematite lamellae may be seen in all crystals examined. Figure 2.1 is a typical microphotograph of an hemo-ilmezaite crystal cut parallel to its c-axis. This photograph shows clearly the hematite lamellae in the

ilmenite host. The hematite lamellae fall into two distinct size ranges,

one of large and some intermediate lamellae, and the other of very

small lamellae. The large and intermediate lamellae range in length

from 1 to 10 mm and in thickness from 0.005 to 0.02 mm. The larger

hematite lamellae are seen to host minute lamellae of ilmenite. The small hematite lamellae are roughly 5 to 10 microns long, 1 micron wide and 0.2 micron thick (Carmichael, 1961). The hematite phase appears as small circular pods or discs in

sections cut perpendicular to the c-axis of hemo-ilmenite crystals (Fig. 2.2). It is evident from microscopic observations that the hema-

tite phase is intergxown in the (001) basal plane of the hemo-ilmenite

host crystal. Such a rely:.onship is expected on structural grounds

for ilmenite and hematiae are isostructurai compounds (Gruner, 191,9).

Intergrewth of this type appears to be the result of unmixing from a

hemo-ilmenite solid solution because the crystal may be rendered homogeneous by heating to high temperature (Carmichael, 1961). -37-

Figure 2.1 Polished section of an herno- ~ilrnerite crystal cut parallel to its c•-axis (X.00).

white : hematite phase gray : ilmenite phase .;Figure 22 . Polished section of an'hemô-::lmenite crystal cut perperdswule,r, to its (X100).

white : hematite phase

gray : ilmenite phase -39 -

Twinning of the hemo-ilmenite crystals wt.s observed in all the

specimens examined. In general twinning is not abundantly developed and

the samples do not contain many twins. However, a few specimens display

excellent (1010) twinning. The best examples of twinning encountered

during the microscopic examination of Lac Tio hemo-ilmenite samvles

are shown in Figures 2.3 a to d. The distortion of hematite lamellae

by twinning is particularly evident in Figure 2.3a; it indicates that

the exsolution of the hematite lamcilae is older than the twinning.

None of the crystals examined showed major distortion of their twin

Manes. This suggests that the Ln.c Tio deposit was not subjected to any

major deformation after its.emnlacement and consolidation.

2.2.1.2 Chamica7.Composition of H,mo-Ti menite

Although the chemistry of the hemo-ilmenite is dealt with in

detail in Chapter III, it is arrronriate at this point to present the

average chemical composition of the Lac Tio hemo-ilmenite (Table 2.11.

These results (Table 2.1) were obtained from the chemical analysis of 48 hemo-ilmenite concentrates which have been prepared from samples that lie within cross-sections ?K ana LM (Fig. 3.1 and 3.2) of the ore deposit. (a) (b) white : hem, gray : ilm. dark : hem. light : ilm.

Figure 2.3 Mic,ophotograOs of twinnétg _iiemo-ilmenite cr;vstPls. 2.3a)Disto.r 4 ~on of hemat,ite, lamellae due to twinning. 2.3b)Twinn51 -1,7 5.n one direction. On that samnlP ~he hematite was etche :' in LoncPntrai:ed HC1 in the presence of copper. 2.3c)e=lidc. ..twinning and twinnirj in two directions. 2.3d)Twinning in three directions. The sezticn shown was cut perpendicular ..o the c-axis of the crystal. Table 2.1

NNW Chemical Composition of Averape LaTio Hemo-Ilmenite Wt.% Mol. Prop. .4743 TiO2 37.9 FeO 29.1 .4035 MgO 2.21 .0548 Mn0 0.16 .0022 .4623 CaO 0.10 .0018 Fe203 29.2 .18271 V205 0.40 .0026 A1203 0.23 .0022 .1881 Cr203 0.10 .0006J

Wt.% of ilmenite phase 70.03 Atomic formula of ilmenite phase (Fe o 87 frig, u8.004 .Ti02 Ca.004) U Wt.% of hematite phase 29.97 Atomic formula of hematite phase (Fe.971V.014A.012 ÿr.003)203 : 0.96% (Wt). Excess TiO2

These results indicate that the Lac Tio average hemo-ilmenite

contains 30 per cent by weight of the hematite, the remainder being ilmenite. Whereas tie calculated formula of the hematite is practically

pure Fe203, the ilmenite contains appreciable MgO (11.8% Mol.) substituting for FeO. The average heLno- 1Jneaite, like most hemo-ilmenite from . The excess TiO lac Tïo,yielck on analysis a slight excess of TiO2 2 can probably be accounted for tj the small amounts of anatase and/or

rutile found in most samples. This LsTect is further discussed in section 2.2.6. 2.2.1.3 Minor Element Distribution i n Unmixed Ilmenite and Hematite

Electron microprobe work was carried in order to determine (I) the distribution of Ti, FP, Cr, Mg, V anf Al amongst the unmixed ilmenite and hematite phases of Lac Tio ore. Using a crystal cut parallel . to its c-axis, an electron probe traverse at right angle to the hematite lamellae was first oùt€fined. The intensities recorded for Ti, Fe, Cr and

Zig are shown in Figure 2.4. A anantitative analysis was next obtained for the above mentioned six elements in the respective unmixed phases.

The results obtained are summarized in Table 2.2.

Table 2.2

Electron Probe Analysis of Unmixed Ilmenite and iieratite A1~

Fe Ti Cr V Mg Al

Ilmenite gro....mass 36.5 32.7 N.D. 0.10 1.7 N.D.

Large hematite lamellae 53.3 8.1 0.10 0.50 N.D. 0.14

N.D.: Not detected

Although the data of Table 2.2 were obtained from spot analysis, it should berointed out that, because very minute ilmenite lamellae are nresent in the larger hematite lamellae and vice versa, it is not possible to obtain intensities that are free from the contributions of minute lnmellae. Dermite these' limitations, the data of Table 2.2 indicate that Mg is preferentially concentrated in the ilmenite phase;, whereas Al, Cr and V are held in the hematite phase.

No attempt was -jade tn determine the composition of ti.;. lamellae since the size of tee lamellae :gis too small for meara:f Igful probe analysis.

(1) The microlvrobe work yes carried out at the Kenrecott Conner Laboratory in Lexington. ;Massachusetts. Iron, titanivaa, chromium, aluminum and magnesium intensities were collected uei.ng routine instrumental conditions. licwever, vanadium intensities were collected using a LiF crystal and slits permitting the resolution of the VKA neak • from the Ti's( peak. 200 300 MICRON

• TY

Mg TENSI IN

ILMENITE Ii.n"ENiTE

Fig. 2.4 Qualitative electron probe traverse across an hemo-ilmenite grain. Detailed explanation is presented in the text. -44 -

Similar work involving iron and titanium only was also carried

out at the Mines Department in Ottawa. Figure 2.5 shows the relative

distribution of these two elements in an hemo-ilmenite grain, The tra-

verse which covers 70 microns distinctly shows the presence of minute

ilmenite lamellae (A) in the hematite and vice versa, the presence of

minute hematite lamellae (B) in the ilmenite groundmass.

2.2.1.4 ,Lattice Parameters and. Composition of Unmixed Hematite and. AMMO 11. 11M,M=1, Ilmenite

Powder patterns of hemo-ilmenite show the presence of both

the hematite and ilmenite diffraction snectra and therefore confirm

the microscoric examination. Since hematite and ilmenite are isostructural

compounds, they have snectra that are closely similar. Only a slight

displacement of corresponding; necks is observed as a result of the

small difference in the axial parameters of the wlo minerals.

Hematite and ilmenite form at high temperature an homogeneôus

solid solution series with ensuing continuous variation in lattice

parameters and other physical properties. Lindsle:r (1962) provided

a graph relating 20 (024) and 20 (116) of hematite-ilmenite solid

solutions to composition expressed in mole % of the end members (Fig.

2.6). This graph enables to determine the composition of hematite-

ilmenite soliô. s^utions by measuring 20 (FeK 1) of the (024) and

(116) reflections.

The (116) reflection of some 150 specimens of Lac Tio hemo-

ilmenite was carefully measured using a Guinier-De Wolff multiple powder

camera and a Nonius-Guinier viewer. Silicon was used as an internal.

INIONMEMBERENAMIIMMEIMMEM 411MMN ~ III

~ r ►

0 10. 20~ 30 40 50 60 MiCRON r

a~ ~ r ITY ILMENITE ENS

NT B

I 4 A .1,,t ^r'i ,r. i1 ~, E ATIV EL 'R HEMATITE A

~ ~

Fig. 2.5 Electron probe trPverse across an hematite lamella, showing the relative distrtibution of Fe and Ti in the two main phases of the Lac Tïo hemo-ilm.enite• ~

L1111j1111111 WHIT It111 1111 I111111 ► III 11111 n1j11►► f:1► 1111► 1j ►. 1n1r11 ► 11 ► 1 ►► 1 ► 1~111j1► 1~~ 63.50 ► ► ►► ► f I r AVERAGE 2a OF LAC T10 HEMATITE PHASE. I .111

AVERAGE 28 OF LAC T10 ILMENITE PHASE-->>y 69.501= . ■ I 1 1 C I = 1 6300 i

I 1 ô 1 ~D I 69.00 ® N o N 8 0 62.50

68.50

1 i

11_111111111111111111111111 111111 t 11111111111,t.L1111111111111111 i 11;y1,11 0 20 40 60 80 100 o- Fe2 M OL. PER CENT FeT103 03 HnlATIT£ ILMENETE

Fig. 2.,6 Liw 37.e.r'a curvetrelating 20 (116) and 20 (021+) - Fe.Kva., with the composition of hema:.ite-ilmenite solid solutions (Lindsle7, 1962). The average 20 anglzs fcr the hematite and ilmenite phase from Lac Tio are indicated by dotted vertical lines. Points (C) and (D) are 20 angles for giekie].ite (M TiO3.ASTI4). Points (A) and (B) are calculated 20 positions for an ilmenite of composition (fr>;.12Fe.38)Ti0 , corresponding with the composition of the average. ilmenite phase from Lac Tin. (See te:ct for exv lanai i n.-) . -47- standard. The average 29 FeKat obtained are summarized in Table 2.3; refering to Figure 2.6sthe data would indicate that the average hematite phase contains 14% mole or ilmenite in solid solution whereas the ilmenite phase would contain osa average 8% hematite in solid solution. However, va discussed earlier, microprobe analysis indicates that most of the magnesium is held in the ilmenite structure. The substitution of Mgt + (ionic radius .65) for Fe/4 (ionic radius .76) should reduce the cell dimensions of the ilmenite. The atomic formula for the average ilmenite was discussed in section 2.1.1.2. Neglecting Mn and Ca which occur only as traces

(Table 2.].)s the average ilmenite formula would be (Mg.12Fe.88) 0.Ti02. Assuming linear re].ationshipc between lattice spacings and composition, the 28 of the (116) reflection may be calculated using the pure end- members diffraction data(1). Such calculations for (Mg.12Fe.88) 0.Ti02 yields : 20 (116)=68.390. When compared to the data of Table 2.3, these results suggest that Mg,substituting for iron in the ilmcnite, is almost alone responsible for the variation in the reflection (116) of the unmixed ilmenite phase. The ilmenite phase would accordingly contain little or no hematite in solid solution. Table 2.3 (116) Reflections of Unmixed Hematite and Ilmenite 28 (116 ) Fei;oll Unmixed Lac Tio hematite (Average) 69.54 Unmixed Lac Tio i.1 s ni.te (Average) 68.43 Pure hematite (synthetic) 69.68 Pure ilmenite (synthetic) 68.29

11) Géikielite (77O.Ti02), sl(116) = 1.708A°(A.S.T.M.) Ilmenite (FeO.Ti02),d(116) s- 1.7244 A°(Lindsley, 1962) iminsizsgammEmEMEIEFWEIW211111111MEMORMINEMERIONEYAMEI'0►

The average hematite calculated from the average hemo-

ilmen:ite from Lac Tic (Table 2.1) contains only very minor amounts of Al, Cr and V, the presence of which should not alter significantly

its lattice spacings. In spite of this, the (116) spacing of the unmixed

hematite is significantly larger than that of pure hematite (Table 2.3). It thus-seems relatively certain, referring to Figure 2.6 that the

unmixed hematite in Lac Tio hemo-ilmenite holds in the order of 14 Mol. % FeTiO in solid solution. 3 Table 2.4 lists the results of unit cell parameter determina-

tion;for unmixed ilmenites and hematites from Lac. Tio and for various

other ilmenites and hematites. The determinations were made wing the

diffractometer with silicon as an internal standard. Reflectiox.s (104)

and (110) were used for the calculations. The unmixed hematite i.. seen to have axial parameters slightly larger than those of synthetic hema-

tite whereas the axial parameters of the unmixed ilmenite are slightly

smaller than those of synthetic ilmenite. Table 2.4

Unit Cell Parameters of Unmixed Hematite and Ilmenite

Cell Paramete.~ta Cell Parameters (hex.sys.)A° (rh.sys.) A°

s.o co arh a4

Synthetic ilmenite 5.085 14.075 5.534 54°42' (prepared at Q.I.T.)

Norway ilmenite 5.084 14.062 5.530 54°44'

Synthetic hematite 5.035 13.755 5.42 55°16' (Fisher Reagent)

Isle of Elba hematite 5.038 13.756 5.405 55°33'

Lac Tio hematite 5.047 13.762 5.435 55°20' phase

Lac Tie ilmenite 5.081 14.041 5.523 .54°46' phase Precision ±.001 .003 t.001 t 1'

.ainiJmlimm EAMIN .. ;L`•=427, ~!"~. -1+9 -

During the microscopic examination of sections cut perpen-

dicular to the c axis of the crystals, several hematite "discs" or

blebs were noted to display trigonal cracks reflecting the symetr;r of

hematite. A good example of this feature is shown in Figure 2.7.

These cracks probably developed from tensional stresses resulting from

the fact that the hematite "guest" has smaller cell dimensions and

volume than the ilmenite host (Table 2.4e).

Fig. 2.7 Trigonal cracking in exsolved hematite phase. The hemo-ilmenite crystal was cut Perpendicular to its c-ax5.s. (X200).

2.2.1.5 Di tribution and Variation of Ilmenite and Hematite in the G e

The distribution and variation of the ilmenite and hematite

unmixed phases. in the orebody was investigated by measuring the (116)

reflection of the minerals in some 150 samples representing the entire

deposit. This work was done with a Guinier-De Wolff X-ray diffraction

camera and monochromatized CoKpt radiation. Although this work did not

reveal major variations in the orebody, a small difference in the compo-

sition of the ilmenite-hematite solid solutions has been observed in

samples from the low grade part cf the deposit. Figure 2.8 which

represents an east-vest cross section of the orebody shows the molecular

-~. .e

) L M ~,~ 1 .. _---- . _~ i • 24, 1 ' ,•, + , ~~y' ,^ zf~.,, i 1 1 : : . : . . • T ~R r:~, : : : : . A ♦ - ' 1 / ; ~ ~:~i=~i ÿ~ ~ ;•• :•- ~•± . _ .. ns ~..T-~'`+` ^ _ ~ _ l'a j.:;:.::'•:•... .7:•:•:::::•"... T79 T ''...•• •.. r ,rnT Su!qt 7.~3.r ~ ♦ , ,. ~ ~.. ~ ~~`~. . .• ~ •.. { ~ • I •- a • ♦ . • \ l'• • • T ' -ri I•• ~ ♦ • :' -' •\ ~# • / • ...... L_ T.':7.5 "r-e 4 ‘, ~ ?i / • , 07,...... ::,, . ~~• ••~ • ♦ • • ~ • - • .r..:• - • •, • e • - -. - • • - • #1 ♦ 7 ~- A; 7 ~~;:ï::; : . : ;'' 93.0 \• . •, ' ' • :;• ♦ ' - ♦ ♦ / ► 't • a .1- a . Sap • i I , - ~~::~: c ~ : ~•~.~:•:: ' ;£' • `:~ • . . ; tt ♦_ • 1 7•~ _ 1 ♦ i7. I ~" ~;.~~~>.~13ip?,;;• :r :,. ~• •~•-♦•,• •• / - v 13. . . • : 1 1 r• n~\•.,~;• ~:..~~. S - ~:: : _ - ' ~ ♦• ~ , .;•~,.c:; '••~.~: :~ • .7:4•4.?~~ ~• - • ♦ :^,••;::•:::• .••'. ?•- ' I • •\ •..-, :L;f•• ~'~ t • 411; !,~ . ' ~ ~ J-, i :r•~~i 1.7~,5 `:•: r:~,'; .%:r' `~: ; + •.' v~ r ' •. •' r_ • i ` ~ - ; ~' 18.0,: .:- .;::::•;•:. .. • r ,+ ~v • .• l',.,',-. j :\i~•.~1 ••+~ :~~•~ ;L ti••':`.:~ .~/~~- 1 \ a - 1:~• .yy `. ~~;~•: •.~;:Yt ?5.t...7 ?i. ; '?•, • ~• , `- ` ,. • • ~ ~: ] .•cl~••.. \: ~~~ ow v ,=.♦ ~ . . ~ i ~~' :': ~" 1 F.A. ~ .•: : :•. . . • . • • ' _,._,~.,, .-,•-• .-~ =`'`''' 4.0 ~ " Q~': ':~, r . . c % 3:.::<~~‘..)...Z.:114 5 ~:~..~;:_:~:.:.::::t ;-:.:.•< ` . a•/ .:::.: • , / ~` ' t+, I ~-,v: fi • `•! :•^:'+~''~`::~vT. ~ • ~~~~iti, ~ • %1' ; - :•t'l3 0 ....:•.,:: Ji • • ~ 1 ~ : ~` ~~ "~ :•: ; • ‘~---- 725;~ = 1 •' , • . A :~~::•:•:...:. ~::~: , . ' • : ':~'', 13.0~ ';' - - 12.0` • • . / ~• • g • ` ♦•• .. Ia -a • • ,••:~: _i 4 ~ ...::•••• `;•:•0: ~ 11 1 -. - %O. :,~ ?. ..`.. -s . ~ •- ..‘,.....1...... ••••••••••• ~ ~ ::: r•;: .z...... 4. .# 2...~~ / • . 44•::044.0-4. ..4%.: ~ I - a ~L•::;;,••:'e •••:',.' .~ ~:•• ♦ ♦ ♦ ♦ = ::i+~ ~:"•'i - •- i • ~ ~ ♦ ,- -• ; / ` ,~; a • 1 1 • , - - / 1 , :, - / ~ • 0'1 , • ° ~ 0 ~ I. tr. -. a , • - a - 1 1, . I I t I • •

~.cGEn.J ^ ! 70%I~w~V~~L~yi4T` 7 DIP SECTION 30-70 % la:•v.o -tLnaEhIY& OF R.":anYMO.:ITZ LAC TIO ILMENITE DEPOSIT SCALE 1"=eco'

Figure 2.8 Molecular percent of ilmenitc dissolved in Lac Tio hematite phase.

~ O 0 -51 -

amount of ilmenite dissolved in the hematite lamellae. From Figure 2.8,

one notes that in the low grade part of the deposit (east+.rn limit),the hematite phase of the hemo-ilmenite contains slightly higher amounts of dissolved ilmenite than elsewhere in the deposit.

2.2.2 Plagioclase

Plagioclase constitutes the larger part of the waste discarded at the beneficiation plant. The mineral is generally coarse-grained and has a specific gravity of 2.7. The feldspar is derived from the anorthosite rocks that enclose the orebody and also form layers or isolated blocks within the hemo-ilmenite mass. In some parts of the orebody the plagioclase is also found disseminated within the hemo-ilmenite ore.

However, this type of disseminated material generally occurs as large zones which can usually be avoided dvxing the mining operations. The disseminated plagioclase-hemo-ilmenite rock probably constitutes less than 10% of the volume of the deposit.

From determinations made using the Rittmann zone method (Emmons,

1943) and from refractive index of fused plagioclase glasses (Foster, 1954), the plagioclase found in the deposit is usually a caleic anIesine (An46Ab54). Chemical analyses of anorthosites surrounding thee orebody are presented in Table 2.5. Sample no. 1 is located in the anorthosite

overlying the deposit, sample no. 3 is from anorthosite that underlies the deposit, whereas sample no. 2 is from the country rock adjoining the deposit to the east. The three samples are closely similar chemi-

cally and mineralogically. Under the microscope the rock is seen to -52-

AO.

Table 2.5

Chemical Composition of Anorthosite from Lac Tio(1)

. Sample No. 1 Sample No. 2 Sample IJo. 3 J.D.H.87-13;6.5ft D.D.H.87-13;635 ft. D.D.H.87-1;1193 ft Si02 54•8 55.6 55.4 A1203 27.55 26.05 27.12 CaO 10.1 9.5 9•4 Na20 5.68 5.57 6.51 K20 o.68 0.96 0.80 Fe0 0.37 0.41 0.30 Fe203 0.43 0.76 0.34 TiO2 0.20 0.15 0.15 MgO 0.24 ., 0.31 0.17 MnO 0.007 0.011 0.007

/ Cale. ap.Comp. An4~Ab47,30r3.7 An47Ab470r5'7 o An43.6Ab51.80r4.6 r1t.~

Comp. Tsuboi's An47 An47 An44 Method _.._.~.....~

(1) Analysed at "Laboratoire de Géochimie Analytique, Ecole Polytechnique". ~ ~ ~.....

- 53 - a~. consist principally of coarse subhedral plagioclase crystals and small amounts(less than 3%) of mafic minerals, mainly interstitial augite and lesser opaque minerals, rimmed with biotite.

The plagioclase of all three samples is antine='th;itic and

contains needle•like inclusions of rutile (Figure 2.16) and minute

hematite platelets. The orthocla:;.e is distributed as minute blebs and lamellae in the plagioclase crystals. Commonly the orthoclase blebs

are aligned along clivage or twin planes. The plagioclase in all three

samples is calcic andesine (An44-47) as determined by refractive index

using Tsuboi's method (Morse, 1968). These determinations agree well with the compositions calculated from the data of Table 2.5, when all

CaO, Na20 and K20 are assumed to represent the plagioclase. On the basis of composition, mineralogy, petrography, structure,

environment of occurrence and in some cases, age, Anderson and Morin

(19691 have recognized two types of anorthosite massifs; the labradorite-

tya massifs are irregular in shape and are composed predominently of gabbroic anorthosite. These massifs contain magnetite, ilmenite and plagioclase of composition Or2_3. Contrasting with the lsbra- An63-45 dorite-type massifs, the andesine-type massifs are domical and are composed mainly of anorthositic rocks. Minerals such as hemo-ilmenite

and antiaerthitic andesine 4th a composition of An48_23 Or6_25 are also characteristic of the andesine-type massifs. On the basis of these

criteria, the Allard Lake anorthusite massif can be classified as an andesine-type anorthosite massif.

- 5'+ -

2.23 Sulphides~

2.2.3.1 General Distribution

Pyrite is by far the principal sulphide minral in Lac Tio hemo-ilmenite oie. ; ;owever, chalcopyrite and traces of pyrrhotite, millerite and Co-Ni sulphides of the linnaeite series have also been

!.dentified in the present investigation. The sulphide minerals generally constitute approximately 0.5% of the ore and occur as one to two millimeter anhedral crystals interstitial to the hemo-ilmenite grains.

Figure 2.9 shows the typical association of chalcopyrite with pyrite in Lac Tio ore.

The distribution of sulphides in the orebody was investigated by analyzing the sulphur content of the ore. For this, a series of 55 samples each representing 10 feet of core were selected in two sections

of the upper portion of the orebody and analyzed using the Leco analyzer.

The sulphur content was found to range from 0.03 to 0.95 with a mean

value of 0.28 percent. This work showed that there is no apparent trend

or pattern in the distribution of sulphur in the two sections investi-

gated; also, no correlation could be established between the grade and

the sulphur content of the ore. For example, values of 0.05% and 0.95%

sulphur have been obtained for samples which have a grade of 94.0% and

93.4+% respectively. The investigation also showed that wide variations in the sulphur content are found in the same drill hc1e. For example, in hole 87-5 (Figure 1..12) where eight core lengths representing 80 feet of continuous ore have been analyzed, values of 0.95, 0.11, 0.12,

0.06, 0.05, 0.28, 0.25 and 0.08% sulphur were obtained. Variations from -55-.

Fig. 2.9 Pyrite (P) and chalcopyrite (Cp) in Lac Tio ore (X120). -56 -

hole to hole were also found in this study. For example in hole 87-6

(Figure 1.11) none of the samples in the 70 feet analyzed contained

less than 0.36% sulphur, while in hole 37-5 (Figure 1.22) only one sample contained more than 0.28% sulphur in 80 feet of ore. In hole

87-5, the average sulphur content was 0.20% while in hole 87-6 the

average was 0.50%. The results obtained in this investigation seem to

indicate that the sulphides are unevenly distributed throughout the

Lac 'iio orebody.

2.2.3.2 Chemistry of the Vulphides

A preliminary study by Dr. A.N. Mariano(1) has shown that the

sulphides associated with the Lac Tio ore contain some copper, nickel

and cobalt. In his study, Mariano et al (1970) determined the cell edge of pyrite to be 5.4191A°.This value is slightly large than the cell edge of pure pyrite (5.14171A°)and may, according to Mariano indicate that some nickel and cobalt are in solid solution in the pyrite structure.

Pursuing this work, the author has studied the distribution of Cu, Ni

and Co amongst the principal mineral phases present in the ore. For this, concentrates of hemo-ilmenie, magnetite, spinel and sulphides

were prepared and analyzed for Ni, Co and Cu at the Kennecott Labora- tories. The results of this work are presented in Table 2.6.

nIMIKIMININIMPr 11101•=1, (1) Kennecott Laboratory, Lexington, MLss. Table 2.6

^istr. ibution of Cu, Ni .and Co in the al

~~..of the Lac Tio Ore

% Co Dist. j Cu Dist.. % Ni Diq; Hemo-Ilmenite 0.009 59% 0.003 50% 0.022 85% Spinel 0.084 5 N.D. 1 0.078 3 Magnetite 0.015 1 0.061 10 0.107 3 Sulphides 1.1 35 0.5 40 -242-----2

Total in Ore 0.0155 100 0.006 100 0.026 100

The results of Table 2.6 indicate that for an average ore containing 0.25% sulphur (equivalent to 0.5% pyrite), 35% of the cobalt, 40% of the copner and 10% of the nickel are found with the sulphides; the remaining amounts are located mainly as solid solution in the hemo-

ilmenite and cannot be eliminated or recovered by physical means.

2.2.4 Sninel Spinel is present in amou:its vzhying from one to three percent

in the ore. In this study, a sample of spinel vas concentrated by

leaching a typical hemo-ilmenite sample with hydrofluoric acid. The

spinel was found to ::onstitute 1.1 percent of that particular sample

of ore. The mineral occurs in Lac Tio ore in three different forme.

By far the most common spinel occurs as one to five millimeters anhedral

grans interstitial to the hemo-ilmenite crystals. However, although

interstitial spinal is the most common relationship observed, some

spinel appears as if included by hemo-ilmenite. It is not sure yet, ..58_ whether the "included" spinel are really included in the hemo-ilmenite or if they are projection from interstitial aggregates from above or below the section. This spinel is pitch black in hand specimen and bottle green in thin section (Figures 2.10, 2.11, 2.20),has a specific gravity of 3.8 and a retractive index of 1.77. Cell edge determination of the spnel using a 114.6 mm. camera yielded an axial parameter of 8.1197±

.00051 . This value agrees remarkably well with a previous determination on anothe: sample, which gave 8.1188 ± .0005A° (1). A partial chemical analysis of a spinel concentrate is given in Table 2.7.

Table 2.7 ,..---- Partial Chemical Analysis of Sninel from Lac T o-Qrs. w 4. t Mg0 19.33 FeO 13.23 Calculated formula .96 Fe203 4.12 (M.172Fe.28)(A1 Fe.04)20 Al203 65.08 1 'I Analyst : Laboratoire de géochimie analytique, Ecole Polytechnique. The chemistry and physical properties of the mineral indicate it is pleonaste, a spinel commonly associated with titaniferous ores (Deer,

Howie, Zussman, 1964).

Another variety of spinel is also found in the Lac Tio ore :here it occurs replacing the hematite lamellae in the hemo-ilmenite

(Figure 2.12a). However, the concentration of this type of spinel is much lower than that of pleonaste. Figure 2,12b to 2.12d are electron probe "X-ray pictures" corresponding to Figure 2.12a; the high alumina, low iron and absence of titanium identify the spinel on the photographs.

(1) Value determined by A.N. Mariano. - 59 -

Fig. 2.10 Photomicrograph showing pleonaste spinel, the most common spine]. in the ore, adjoining hemo-ilmenite: (h) etched hematite, (i)?menite, (s) spinel (X400)

Fig. 2.11 Grain of green pleonaste as seen in transmitted light (X120). - 60 •-

(a) (b) Al

(c)mTi (d) - FF Fig. 2.12 Replacement of hematite by spinel. (a) Fhotomicrorranh showing spinel invading ilmenite along hematite lamellae. (X400) (b,c,d) Are electron probe "X-ray pictures" showing the distribution of Al, Ti any. Fe in region (a). (X240). -61-

A third and much rarer variety of spinel is also found in the ore. It usually occurs close to the boundary of hemo-ilmenite crystals. Characteristically, the ilmenite adjoining this spinel has a border zone devoid of hematite lamellae and often contains rutile

(Fig. 2.13 and 2.l1). Electron probe traverses across a spinel grain and the. bordering ilmenite rim has shown that Fe, Mg and Al decrease regularly from the center to the edge of the grain. From the edge of the spinel grain outward across the ilmenite border zone, the relative amount of iron increases while that of titanium decreases. No significant variation could be recorded for Al and Mg in the border zone of the hemo-ilmenite crystal.

Mariano (1970) has reported the presence of gallium in the spinel of Lac Tio ore. Persuing Mariano's work, a concentrate of spinel was prepared and analysed for gallium. The results showed that 0.1% gallium is contained in the spinel where it typically substi- tutes for Al. This amount represents one third of the total gallium content of the ore. Although gallium occurs in trace amount in the plagioclase, the remaining two third mainly occur as a solid solution within the hemo-ilmenite.

2.2.5 Magnetite

Magnetite generally constitutes less than one percent of the ore. In a group of 48 samples taken from sections JK and LM (Fig.

3.1 and 3.2) of the orebody, only two samples contained as much as

3 percent magnetite. The mineral occurs in three different forms in

the Lac Tio orebody. The most common magnetite is found replacing the -.62-

~ ` ~•..~~ t , ~,~, :~•~~~ ~` ~,, . ~..'~• .,.

..~ • ~s°. \. .' ~~,•~'~.` ,~~:\` ~ . \ ~~i.•,.; ~ ~ `ç ~ •`~ . • •

ti `~. .'\``e `~•, ,.f~µ •

Fig. 2.13 Spinel (s) of the third variety adjoining an hemo-ilmenite crystal. Note the hematite free rim adjacent to the sDinel (X400) .

Fig. 2.14 Spinel (s) adjoining hemo-ilmenite. The presence of rutile (r) in the hematite free rim may be seen (X450). -63-

exsolved hematite lamella (Fig. 2.15a). This type of magnetite occurs principally along cracks in the hemo-ilmenite crystal and seems to be responsible for the variation in magnetite content observed in the orebody. In many instances this type of magnetite has been found associated withhsecondary anatase (Fig. 2.15b). Indeed, microscopic observations of selected ore samples commonly show the alteration of ilmenite to anatase together with the magnetite which has replaced the hematite lamellae.

A second type of anhedral magnetite is present in small amounts in most ore specimens where it is found associated with the sulphides. A typical example of this magnetite which probably represents less than 0.5 percent of the ore is shown in Fig. 2.15c. The lack of alteration products and the well defined grain boundaries seem to indicate that this type of magnetite is primary. Attempts to concentrate this magnetite for chemical analysis were not successful.

However, it was possible to analyse (1) some magnetite grains using the electron microprobe. The results showed that the primary magnetite is almost pure. Indeed, except for titanium which is present in the amount of 0.20 percent, no other elements could be detected with the microprobe. On the basis of these results, a content of approximately

1 percent ulvospinel in solid solution, has been calculated for the

Lac Tio primary magnetite.

A thin, type of magnetite is occasionally found along the main faults of the orebody. This type of magnetite is not very abundant;

(1) The analysis was carried out at the Kennecott Laborator.es,

Ledgemont, Mass. -64-

(a) (b)

a)Typical microphotograph showing magnetite (m) replacing hematite (h) lamellae in hemo-ilmenite (X200). b) Secondary magnetite (m) replacing hematite (h) (X400). Note the association of anatase (a). c)Primary magnetite (m) adjacent to a pyrite (p) grain (X400). -65 -

it occurs in zones a few inches thick and is usually associated with chlorite and rutile. This type of magnetite was not studied further for it is clearly post ore in origin and probably results from special physico-chemical conditions developed during the faulting.

The oxygen fugacity and temperature of formation deduced from this magnetite would not represent conditions prevailing during the formation of the deposit.

To summarize, the Lac Tio hemo-ilmenite ore contains very little primary magnetite. As explained in section 2.2.5, the variations in the magnetite content. of the ore is probably largely due to the varying concentration of the secondary magnetite that replaces the hematite lamellae. Due to Lh,, rarity of primary magnetite in the orebody, it is almow, i::possible to determine satisfactorily the conditions of temperature and oxygen fugacity prevailing during the formation of the deposit.

2.2.6 Rutile and ;natase

Rutile is found only in very small quantities in the Lac

Tio orebody. One of the main occurrence of the mineral is near the main faults where it is sometimes present together with magnetite in widths of a few inches. Rutile needles are also commonly observed in plagioclase (Fig. 2.16 and 2.17a) of the anorthoeite where it probably accounts for part of the small quantities (0.20 of TiO2 in the analysis of anorthosite (Table 2.5). In polished sections of ore, rutile may be seen to invade the hemo-ilmenite crystal, in the border

zone of spinel grains (Fig. 2.14). The rutile distribution is well

shown by the Ti electron probe scan (Fig. 2.17x). -66 -

Fig. 2.16 Inclusions of rutile in plagioclase. Polarized light. (X200). - 67 -

(a) (b) - Al

Fig. 2.17 Distribution of rutile in hemo-ilmenite

a)Rutile (r) invading ilmenite (i) near a spine' (s) grain (X400).

b)Distribution of spinel in region (a) as indicated by electron probe "X-ray picture" of Al.. (X400).

c)Distribution of rutile in ilmenite as indicated by electron probe "X-ray picture" of Ti. (X400)

d)Distribution of Fe in region (a) as indicated by electron probe "X-ray picture". (X1600). - 68 -

Similar to rutile, anatase is present only in trace amounts in the orebody. In a group of 133 ore samples studied by diffraction, only three samples contained enough anatase to be detected. Microscopic examination of these three specimens has shown that anatase is a product of alteration of ilmenite and forms preferentially along cracks and twin planes. Figures 2.18a and 2.13b show the typical association of anatase in the ore. The mineral is often found with secondary magnetite and is always surrounded by a rim rich in iron. The phase that forms the rim has not been identified; however, electron microprobe analysis shows distinctly that the iron concentration is higher in that region

(Fig. 2.19a to d) than elsewhere in the crystal. In Figure 2.18b it is interesting to note that the small hematite lamellae inside the anatase grains have remained untouched during the alteration of ilmenite.

In the course .af thi. a study no important local concentration of rutile or anatase have been found in the orebody. The quantities present in the ore are too small to influence appreciably the TiO2 content.

2.2.7 Chlorite and Biotic

Chlorite is not distributed evenly in the orebody and it is difficult to evaluate its concentration. The mineral is mainly found near the faults and in the heavily fractured areas of the deposit.

Although magnetite is commonly associated with chlorite in fault

zones, the. relationship between the concentration of chlorite and

magnetite has not been studied in detail. However, examination of the

geological log of the drill holes, seems to indicate that the amount of magnetite is. highest in the vicinity•of chlorite. Small.amounts of -69-

(a)

Fig. 2.18 Distribution of anatase in hemo-ilmenite.

a)Microphotograph showing the alteration of ilmenite (i) to anatase (a) along cracks (X200).

b) Microphotograph showing the alteration of ilmenite (i) to anatase (a) along twin planes. Note the unaltered hematite lamellae within the anatase and the iron rich rim bordering the grain (X400). - 69 -

(a)

(b)

Fig. 2.18 Distribution of anatase in hemo-ilmenite.

a) Microphotograph showing the alteration of. ilmenite (i) to anatase (a) along cracks (X200) .

h) Microphotograph showing the alteration of ilmenite (i) to anatase (a) along twin planes. Note the unaltered hematite lamellae within the anatase and the iron rich rim bordering the grain (X400). - 70 -

(a) (b)

(e) - Ti (d) - Fe

Fig. 2.19 Alteration of ilmenite to anatase.

a)Microphotograph showing the alteration of ilmenite (i) to anatase (a) in an hemo-ilmenite crystal (X200).

b)Absorbed electron image of region (a) (X400).

c)Distribution of anatase in region (a) as shown by Ti electron probe "X-ray picture" (X450).

d)Unalte;^ed hematite within anatase and the iron ri.:h rim bordering the grain (X400). 71

chlorite also occur as a reaction product separating hemo-ilmenice and plagioclase or as an alteration product of biotite (Fig. 2.20).

Minor amounts of biotite are found in the Lac Tio deposit.

Unlike the concentration of spinel, which decreases proportionally

with decreasing`ore•grade, the biotite content probably increases as the grade of the ore diminishes. However, even in low grade material

(80%), the mineral does not constitutes more than one percent of the ore. The mineral is brown in thin section and commonly occurs as rim separating hemo-ilmenite and plagioclase (Fig. 2.21 and 2.211).

2.2.8 Apatite, Corundum and Zircon

Apatite, corundum and zircon have been found in small quanti-

ties by the author. The minerals were identified in a concentrate of

sulphides prepared from high grade hemo-ilmenite ore. These minerals

are rare and constitute only a very small proportion of the ore. For

this reason, they were not studied further as they are not susceptible

to alter significantly the composition of the smelter feed.

Figure 2.22 shows a corundum crystal included within an hemo-

ilmenite grain (1). A similar occurrence of Lpatite crystal was also

observed in one of the several polished sections examined by the

author. The particular crystal was identified using the electron

microprobe.

(1) Microphotograph taken by A.N. Mariano, Kennecott Copper Laboratory,

Ledgemont, Mass. -72 -

Fig. 2.20 Microphotograph showing chlorite (c) separating hemo-ilmenite and plagioclase (pi. One also notes the presence of spine! (s) and the replacement of biotite (b) by chlorite (c) (X35). Fig. 2.21 M.crophotograph showing(brown)biotite in anorthosite. Note the rim of biotite bordering the hemo-ilmenite (X35). Fig. 2`.22 Euhedral corundum (brown) included in an laemarilmenite crystal (X600). 2.2.9 Hynersthene and Calcite

Although hypersthene is a common ccsnstituenu of the anorthosite country rock, the mineral occurs in only very small quantities in the ore. The amount of magnesium contributed to the ore by this mineral is negligible for the mineral generally constitutes less than half a ner-- cent of the ore. Figure 2.23a and b show hypersthene grains associated with plagioclase in anorthosite. The conaosition of the hynersthene mineral determined by Hargraves (1962) is given in section 1.5.2.2•

Calcite constitutes only an infinitesimal portion of the ore. The mineral is observed in rare specimens as inclusions in plagioclase (Fig. 2.24).

2.3 i•IineralorTical Summary

The iron and titanium ore at Lac Tio is made up almost entirely of hemo-ilmenite of average composition Fe203 (30f) FeO.T102 (700 The original high temnereture solid solution of hematite and ilnenite

has unmixed to a regular lamellar intergrowth of hematite and ilmenite.

Chemical analyses together with microprobe analyses and crystal chemical

considerations indicate that the unmixed Phases have an average comno-

sition as follows :

hematite : (re .071V 014Al.01?_Cr.004)203

ilmenite : (;4r,118t1n.004Fe.873Ca.004)O.TiO2 Pssocigted with the hr•:mo-ilmenite are small amounts of Pri-

mary minerals, the principal one being,.nlagioclase An46Ab54, commonly

•antinerthitic, pleonaste spinel and. pyrite. Others such as magnetite,

zircon, hiotite, corundum, auatite, chalcorvrite, millerite, nyrrhotite,

Co-Ni sulphide of the linleite series and hypersthene have also been -76-

(b)

Fig. 2.23 Microphotographs of hypershenP in plegioclase

a)Hypersthene grain in nlag:.oclase. Note the biotite inclusions in the crystal. Polarized light (X32).

b) Hypersthene (brown yellow) surrounded by plagioclase ;.z-ystals. Polarized light (X35). .- 77 -

Fig. 2.24 Microphotograph showing calcite i;clrsions in a plagioclase grain. Note the biotite rim separating plagioclase and hemo-ilmenite (black) (X100). - 78 -

found in Lac Tio ore but all of these are present in only very small

amounts.

In our mineralogical investigation, a number of secondary

gangue minerals have also been observed with the hemo-ilmenite of

Lac Tio. These minerals are, chlorite, magnetite, rutile and anatase.

Chlorite, magnetite and rutile are commonly found together along

faults and in heavily fr3etured zones of the orebudy. Similarly,

anatase and magnetite commonly occur together. Indeed, whenever a

major concentration of anatase is observed in the hemo-ilmenite,

secondary magnetite can be found.

This study has shown that, in general, the Lac Tio hemo-

ilmenite deposit may be considered as mineralogically homogeneous.

A few exceptions to this are given below :

1•. The sulphide minerals seem to be unevenly distributed in the

orebody. However, the present work could not establish any trend

or pattern of. distribution for sulphides in the depoLit.

2.The amount of ilmenite in solid solution in the hematite phase

of the Lac Tio hemo-ilmenite is slightly higher in the low grade

part of the orebody than in the higher grade portions.

3. No important concentrations of rutile or magnetite can be found

in the Lac Tio deposit.

4. In rare cases, the ilmenite phase in Lac Tio ore is altered to

anatase. This transformation which occurs preferentially along

cracks in hemo-ilmenite is•often accompanied by secondary magne-

tite. Similar to rutile, no major concentration of anatase exists

in the deposit. s -79 -

These observrtions would suggest that, except for grade itself, there are no mineralogical factors susceptible to alter the future mining operations. In the light of present data, nothing could be gained by selectively mining the Lac Tio deposit.

Our study of the crystal chemistry of the various minerals of Lac Tio ore gave the following results :

1.Most of the magnesium in the ore is found it the ilmenite phase of the hemo-ilmenite minerai.. As expected, the magnesium

ions (Mi ) replace preferentially the ferrous ions (Fe:") in

the crystals.

2.The sulphides in the average Lac Tio ore contain 35% of the cobalt, 4O% cf the copper and 10% of the nickel. The remaining

cmounts are mainly found in solid solution in the hemo-ilmenite.

3.Pleonaste spinel contains one third of the total gallium content of the ore. Again, the remaining amounts are in

solid solution in the hemo--ilmenite. The above results show that most of the magnesium and a large part of the Cu, Co, Ni and Ga are present as solid solutions in the hemo-ilmenite of Lac Tio and therefore cannot be recovered by physical means. These crystal-chemical considerations and the low concentrations involved suggest that at present time, no minor elements are worth recovering from the Lac Tio deposit. 80

CHAPTER III

GEOCHEMISTRY OF HEMO-ILMENITE FROM THE LAC TIO DEPOSIT

3.1 Introduction.

The purpose of this chapter is to describe the chemistry and the chemical variations of hemo-ilmenites in the Lac Tio deposit.

For this, concentrates of hemo-ilmenite of high mineralogical purity were prepared and analysed chemically for Fe, FeO, Ti02, MgO, V205,

Cr203, A1203, MnO, Ca0 and Si02. Because great care was taken to prepare concentrates containing on average more than 99% hemo-ilmenite, the data reported in this chapter provide a detailed and fairly complete view of the chemical variationP to be expected throughout the orebody.

3,2 Selection and Preparation of Material for Study

In order to insure adequate representation of the orebody, the'samples were obtained from diamond drill holes contained in two sections that are approximately perpendicular to each other. Section

JK (Fig. 1.11 and 3.2) intersects the oval shaped orebody along its length and is referred to as a strike section; section LM (Fig. 1.12

and 3.1 is referred to as a dip section.

A suite of 48 samples, 22 from section JK and 26 from section

LM, were selected for study. The samples were selected irrespective

of grade and attempts were made to choose samples which represented

ten feet of core. Figures 3.1 and 3.2 illustrate the specimen locations

in sections JK and LM respectively.

~ M

° -- -- A '1'.. rr' Sc.ri~~ ^. st siiis • ~ T7) 7 Aresa , /° ~ •~:: ::% ;~`:a~:(~:•::~Ÿ; i ~ ~~~~.. e • T.77 •. •t Surfae i •• %~. • •• •. - • -c: T8â•9 • ' • 1 1 •. ° • • ,.:::•. ,, . ~'./` c.:: 7-,37.5%"' dalr ``' ./~ . ••= • : ~ • '' • -, -: ~.~• ; ••• . . /•``~'.. : .,, •.i' ~. ~^'~ i 8 ~ •••`.•. ~...•• ~ I . , t • ~ ~ ~ ~%~? ~ •"^:. _ 3~. 1164 L •~ • ~ •i •° 500 : ~: :•: :;v .• : . .~ • • •~ • ,, . • . , ~ ~ • ~ ., /. ° , ,_1::~ 7aS :: II` ~ 117r~?,: ~ '` I e • ? 1l •~.= ~s _ `• • = • • ..r • . ~ i t ~ .:.`.,. ~ ~• • 2oi9 + •• •~ wt2^~?` •` IOD6911'17 :_1:~r.'~ ~'~ .~;::?•, ~~rr•~ .~•;•~` • y :- ,. •. ': `~: 91 . .:::.'~;. .. ~~'r• j~^\ = ♦• . . •~'<':,.: r ~• _,;• . 1 r~ • ~j`,• •~ i. ~'â-. ; C•0~L. • : ~tt6~~`?•:'>; ,• 0 •' or ~ %~ l ;•• 7wie~;•:i.l,._. ~~!' t.% i~ ~ . .•z ~ ,', • ~~:~~ ÿ e+: 1 : .. :.; . r~~? ;•~/• r • '1•, ‘ (~..~ 7~5~ ~ ..v:v. ..: ••, ,` •/, • r; ~ • • ..%:•:•••••~ ~ , . • • • -s..., 1 . \ \ ..~ ~ . 1 / ~ . . - •; •~~„;ï•~:_ . ..;: ;:;: 1 . • . ~ .v•~,.•. ~Dh~ • •~ s ~ ;~~•% .. . ~ •. • • • ~ '• ~ ,.0 :;: : ::~ •• • . • • ~ • ~~ ' . I f : • • f `/ • 1 - ~ •ŸV - •:•: :::'. '^ , I •• 0 ~ \~ \ ~~~.:ti~•iV✓••~ , ` • ` ~ .• t t . I, ♦ ~ • • , ~ \ • • •' , i/ ~ ~. 1 , 1 t ‘ . ,•„ • • .. 1 am, I ' ° ,~ ~ ••~„ ! • % • . ,. ~ • ~ • •• w . I- • t •:.•%•% 1„. I ~ , t I • •

LEGEND ~ 70% /4.1M3-ILP.;~r1tTE DIP SECTION 30.70% ki•10-EI.AtENiTfi ~ OF •\\i APJoRTK6ZlY~ LAC TIO ILIVIENITE DEPOSIT SCALE :"_Lno°

Fig. 3.1 Dip section: o`' Lac Tio orebody. The numbers are those of the diamond drill core samples.

•

? .71"93'"; ^ -- ~ •~ .r T-78. ,..O T-67-2 ? 7-64-! 7—8..—~ 0 +~ ~, - - - .... .:•:'• ~.. , e5.en r Svtr.,.r T-87-- ~ 67 Sio 2a7 :.r~.-% 6 9C:"~.c`v - _.:.•::::::::: •.::. 3a ~"• ...... ... ...... :.~:•.~.:.~..;~^ ..~~.::r'•:''{~:•'}253 ....- . .. _

LEGE:~D STRIKE SECTION > 70% HEMO-1LMEAlITE 30 :TO % c15it70.• 11.MEw1TE LAC Y10 iLMEN6TE DEPOSIT • ,. ANqRYKGtTE Sghtz i"a âCo'

LAKES

Fig. 3.2 Strike section of Lac Tio orebody. The numbers are those of the diamond drill core samples. -83-

The hemo-ilmenite ore samples were then subjected to careful mineral separation treatments in order to obtain concentrates of hemo-ilmenite. The details of the mineral separation procedures are given in Appendix I. The average concentrate obtained after these procedures consisted of a black -150 +200 mesh powder containing more than 99.hemo-ilmenite, the principal impurities being odd grains of spinel, F;.Tite, plagioclase and pyroxene.

3.3 Analytical Methods and Preparation of an Hemo-Ilmenite Standard

All of the chemical analyses required for this study were

done at the Q.I.T. Research Center at Tracy, Quebec. The major consti-

tuents, Fe, FeO, TiO2 and Si02 were analyzed using wet methods whereas

14gO, V205, Cr203, CaO, Mn0 and A1203 were analyzed by atomic absorption.

The analytical procedures were controlled by usi ng a specially prepared

hemo-ilmenite standard. A concentrate (approx. 5 lbs) of high purity,

hemo-ilmenite was prepared and samples of this standard were inter-

calated at random with the samples to be ana2.yszed. The preparation of

the hemo-ilmenite standard is described in Appendix II together with the

results of twelve replicate analyses of the standard. The mean compo-

sition of the hemo-ilmenite standard, the standard deviation and the

analytical variation attached to the various determinations are given

in Table 3.1. 84

Table 3.1 441111. Ma.ior Element Composition of Hemo-ilmenite Standard Element Standard Deviation Analytical Variation(3) Fe 43.1 0.2 0.48% FeG 28.2 0.2 0.71% Fe203* 30.3 0.3 1.0% TiO2 37.6 0.2 0.53% MgO 2.42 0.03 1.2% V205 0.42 0.03 7.1% Cr203 43101° o, (S 0.01 10.0% A1203 44 P- ®; 35. 0.01 . 5.0% Si02 0.15 0.04 26.6% CaO o.o / o.J1 10.8% Mn0 0.16 0.01 6.3% Total 99

* Calculated Wt.% of hematite phase : 31.04% Atomic formula of hematite (Fe.97A1 0.013V0.014 0.003203 Wt.% of ilmenite phase : 68.63% (Fe. )0.TiC2 Atomic formula of ilmenite 86Mgwi3Mn0.005Ca0 003 Excess TiO2 : 1.92%

The minor elements in the standard hemo-ilmerite are presented in Table 3.2. Of these, P205 was determined by the wet method,sulphur with the Leco analyzer, potassium, sodium, cobalt, nickel and copper were analyzed by atomic absorption methods and gallium was analyzed by X-ray spectrometry using Ge02 as internal standard and Ga203 as a spike.

1) Also known as the coefficient of variation. -85-

Table 3.2

Minor Element Composition of Hemo-Ilmenite Standard

Element .~.... Analytical Error S 0.01 ± 0.002 K 0.004 ± 0.002 Na 0.011 ± 0.002 Co 0.009 ± 0-0011: Ni 0.022 ± 0.002 Cu 0.003 ± 0.002 Ga203 0.002 t 0.001 P205 0.009 t C.003 Total 0.070%

From microprobe results discussed in Chapter II and from tl'e results of careful microscopic examination of the standard hemo- ilmenite concentrate, it would appear that the crystal chemist ^f the hemo-ilmenite involves principally Fe, Ti, Mg, V, Cr, Mn, Al, Co,

Ni, Cu and Ga; the minor amounts of Si, S, K, Na, Ca and P reported in the analysis are most likely due to rare mineralogical impurities such as pyroxene, plagioclase, pyrite and apatite.

3.4 Chemistry of Homo-Ilmenite in the Deposit

The results of the chemical analyses of 48 hemo-ilmenite concentrates obtained from sections JK and LM are contained in Appendix I. These data are summarized in Table 3.3 where the range, the mean and the coefficient of variation of each constituent are given together with the gracie, the Fe/Ti02 and the Fe203/Fe0 ratios. - 86 _

Table 3.3 ... Chemistry of Lac Tio Hemo-il.menite (1)

Oxides Hirsh Low Mean S.D. Coeff. of Var.(2) Anal.Var.

TiO2 39.6 36.7 37.9 0.65 1.71$ 0.53% Fe0 30.7 27.5 29.1 0.77 2.68 0.71 Fe203 32.2 25.7 29.2 1.39 4.79 1.0 V205 0.47 ' 0.35 0.41 0.03 7.32 7.1 Cr203 0.24 0.06 0..1 is 0.04 34.0 10.0 A1203 0.35 0.17 g2403a0.04 16.9 5.0 Mg0 2.48 1.50 2.21 '0.23 10.4 1.2 CaO 0.14 0.07 0.Cî0 0.01 9.7 10 Mn0 0.20 0.15 0.17 0.01 6.o 6.3 Si02 0.53 0.10 0.23 0.13 - - Grade 97.3 94.8 96.2 Fe/Ti02 1.202 1.058 1.135 Fe203/Fe0 1.160 0.837 1.004

(1) See Appendix I for complete data standard deviation x100 (2) Coefficient of variation '-•-•=, mean

A glance at Table 3.3 indicates that the largest and most significant variations are recorded in Fe203, MgO, A1203, Cr203

whereas TiO2 and FeO, althouth ^ignificant, vary much less. The variations for CaO, MnO, V20, are of the same order as their respective analytical variations and therefore must be regarded as

unsi&,nificant. Likewise, the data of Table 3.3 show that for the

average specimen, the maximum prade obtainable following a nearly

complete mineral :separation is Q6.2$ and its content of Mg0 is 2.21%.

Also, on average, V205, Cr203, MnO, Si02, A1203 and Ca0 cannot be decreased below 0.41, 0.11, 0.17, 0.23, 0.23 and 0.10$ respectively. The average Fe/Ti0 ratio to be expected for an hemo- 2 il:nenite concentrate from Lac Tio ore is 1.135 and that of Fe203/Fe0 is 1.004. -87-

'the results obtained on the 48 hemo-ilmenite concentrates

(Apnendix I) were used to investigate the cheoical variations in the orebody and to define the inter-element correlations within the hemo- ilmenites.

3.5 Chemical Variations of flemr-ilmenite in the:Ors In the hone of discerning trends or patterns of variation within the Lac Tio orebody, the results of Appendix I were plotted on the cross-sections JK and Lfl.

Figures 3.3 to 3.8 ill_ustr-sjt;e the distribution of TiO2,

Fe and MgO in the deposit. Similar diagrams constructed for Fe0,

Fe203, A1203 and Cr203 are given in Apnendix III. The distribution of CaO, NnO and V2 05 were not studied since they cannot be differ- entiated from the analytical error.

Our investigation shows that the hemo-ilmenite is largely homogeneous in composition throughout the Lac Tio orebody. A few excefitions occur in regions of ?.ow grade ore (30 to 70% hemo-ilmenite) where the levels of FeO, Cr203 and SiO are higher and those cf MgO 2 and A1203 are lower. No other compositional trends or patterns could be detected in the orebody.

Lister (196 6) has rennrted a trend in the concentrations of MgO, Cr203 and V205 from the ton to the bottom of the massive part of the Lac Tio deposit. However, our study which involves a large number of samples, shows that no such stratigraphie variation exists in the orebody.

In the light of present data on hemo-ilmenites of Lac Tic,

/ — /• ' -P •. r:...r-ri: • \ ~ i • C•: : :.;; .:c_?~~~.-sl,~•:~„^ ~ :: ::;;: • "" T i-t ~ / i ~ :•..;i;. . ;... Pr S 1 t1 •. ~ .r.~•u- Ÿé ~ •'l •' ..~ `y e:e:42. • C~+-• .. Ilia O. g3• t ~ 0 1 l • .. • •1 • . , r~ï-93-9 , 9 • ~ l.•:v: : . T-37.5 ••• T•Zq.3 • /• •I / •% / / ~ , ~~•!,•:: • • ~ • * • .f . ...% rOo - ~ • ~ • / • • 1 ., -) , .. 1 1 • • • • ,•, • .•. •.: : . • , 1 • • Sen •, ~ • 1 • 1 ~~ • t...... • ,... 1...%:::• - , • •~~ ~ !. ~'~ 1 ..~~ •~. '..14...,1 ", • • 7,i•, ` e- i • :...7...... ,W• • ~T• }~ .~•~i~rM,~ '_ / I • s , • • ••• ••ir i' 'I • I 1 2l, \. \ . • „♦ •r..~'~ti mo••A • •• , 1- • ~\ ''•' ::;:::~s•.. ~ ~~ . :. ♦ S-0. l.evni e• • vJ ~' ~~ i♦ Y~a':':. ~ :i. ,~ • 3T.Vy ^.` . •`•f •• ✓r / . • ?'~ • . ~ A : ; ~.~ ~. ~ •; °% ~'' .....A...... „ 1. • . •v` :~• ~•: ::•••••• •-• ~•~i / / • ~ 1ÿ: .1.... ~.:.; • • I.~ ~ ÿ( :`• ';:::;: ::: :• •_ . . ~ • •• . ~, . ' ~ :"'': \ - ..i . :•»....1;:::•:•::, .•.:•::•:; . :;: s • 1 r . • .,1 • • •• ~ • ~ .~- .-. ~ 1 , / . . • / • ,~: •:•.~::: ••'• •~ `~•I ~, ~' .:•:..•':;: : :•• / ~ / ~• ~ . '• L •r,.~•.~ , _ .. : •:: •.: • ::•::.'. . .. ~ . , . I ♦ I ~+`• .:5,;,~ ï : :• .;.; . : • _i ~,1 V\ , • ~ % ~ \ ` •~ ; ~•` • ~i ~: 4?~;; ~: ~ r1 -•.~ ~% ~ :;:: : ? 1 / ~ I I :•:•: :?) 1 1 ! , ,, ~ .~`T`:~ —`-i ..?•.N~ .~:,`~' h.1n • � ,~' / • ~i • ~ , . / • •. ~• 1~•••• ~y ••: . V 1• . •_ . ~ . : . . ..: •• •K•' :•: :.; .\ •• 1 ~_- / • 1• • .{. :• : :::•.•:::•..::::.. •+..:21.;& ~1 • .... . 1 ~ • ~ ~ ; - i 1+• ~• YÎ':•+: ~ ~ ~ ;:::.iitiil ' , • ~ I • ,, / i •: •♦ • ~ , - 1• • a ~ / , •; 11 • 1 1 • - • • ~ • I - Y ~ • ~ ~ I • • , ~ 1 ~ • ~ • • ~ , • Ir 0~ 1, • • 1 • 1 1, ►• I .r • 1 1 • •

LEGEND

70% Kzte.D-I:t+4zN.TE Fai % DiP SECTION so-7t~ 1%,hë. ~:o -II.M.Er: IVE ► OF IMI,dI~~•7aNI\i:./~~ ~1~ 1+~e u rr e~ ~M LAC TIO ILMENITE DEPOSIT SCALE 1"=C,00'

Fig. 3.3 Percent Tin_ in hemo-ilmenite concentrates of geological `section LM.

a o .ao d 7 1,000 ••• ? ~ 41.1.• ` ft. -1 `~ ~ ? •. ~ -- ~ ~ ... ~ ••"" ..,T-4 -4 ... -- —' ; 1-64-1 T-67-2 T-71- 8 'C--- •.—• a T-:5-9 .. T-7a-2 Y- -5 T-83-1 -•- .~ ti 79 ~, •.- • 97-- P'ce,Cr,— y.,aa.•....T-B3-hr✓; ~ ~ r. • 7t•r►.•tniti � ~~ A•)Ai•~ •:~ 39 . . . : 1 l 'a~`•~ ~:::;: 37;g ...,. ~v^_ .,~ •i/"i;~• ~;;pp~~'~~ti ~ 11~.•.~—~ •% ~ ! Î. ~• ~[:➢71 ~ I • rjOO —~—~ . ~ ~~~,'• g :p':{•:•::. i ~K ' ~~ ~ ~ / • ~ ~~ • ,-~3r.v • 1 ~`' _..,. •$' 1 . i ~ J ~ i 1 ~ { • ••• -1!r' ~':'ti• ~1 +;.'i i: ~ ";~ :;:};:;: •I / • , t \ / •, • 1 ~ ~ ••• •I 1 { ; • 11 ••• ♦ J s I ~ a • / ~ ••• a \ ~ / I - 1 • 1 i 1 1 ♦ ,• a / 1 \ • ~ -' ~.• ~•, ' , f ~ - - -•: : `T.9 • •: :, :' ;•;.;~ s ` ; ; ~ + . •• ♦ / a'~'v`. ~:. •: - ~••:::•: 9Z %\ / 1 ' 1 ~1 1 / 1/f ~ I L . ♦ : :•: . ~ %.~+• - ♦ 1 if~~M I a 1 \ I • I~ ~~ i; / I`\ 1 °1 1 I 5 $ t • . r / 1 ► • / 1 `' 1 1 • I J 1 - / ',• • ~ ~ { - ~ % i % ~ . 1 1 ~ l' - • /. I \ / ~ . / ~ f , ' r — / { i .. ••• 1 - e. s e - ••••mtriowto•••anr.. 5 .~~~\ !_500

LEGEND STRIKE: SZOTiONk > 70% t;:N0•1Li\.Et31T~ OF E:1 30-70% HEW- ILMZNITE LAC 1710 iL.MEbdITE ©EPOSr s • ANOFtTI:OS! T F $Cqi.O? INs 6O0' Era LAKES

Fig. 3.1 Percent TiO2 in hemo-ilmenite concentrates of geological section JK.

\ • • e'4 .` ••. yu.,er,~ ~ i \ <:~ —; •i:~:-:~ 1 .• ::::Jÿ: ~ ••'~ • - C' -• ♦ I1 :1 - It %~ ;~' i =~•y,,' :::.?~~,s .•:• • ,.J1 .,Ji I '~ ~9 ` :~ j ' • T'83- ♦ ~:• ~-....c~ I I , 1•e ~ . 1 I ` . i s T•?l-9 . ~ , r \ ♦ ` 4:.:.: ~L ••••"..% I C7-5 -•••• 7-2?-7+ • ••. •... t / , ~ ♦ t 11 . % ` •' ♦ -.,..•,...,.,..: 1 • I ~ . . 1 o _ -.. . ` , • t - \ • . 9:._ • • ~ It e i`~~ -`;- . ; , • -• . '` ~. ~ :~.: •': .. . _ _~ ._ .. ~' : ♦,'~ /`•. - 412_ \ / t I %`• ~ j ;~. • ~ • , 1 . '% c♦?~ • o ` I`` ..~._. ',;..N.. • ; • / r J... ` e V t \ ~ . ~.,;a ~ .47., .:1• • ~ T3• • •• ® ~:,rÿ e ` ♦ •~'~ • . ' t •T-••~ 1 •.••~ ' I ,-.• ~: ' • • •• :- - . • t p3 ' ..~ I .-~'~ ~_ _ •-t :~ Ï•r"•.•• ` ♦ . \ . vi i♦ ~ - .2.1‘ .. - \ . \ i1 . '~•. C•t?.S.- ~~ 2 - •~-. '.- - , r I ♦. . ,~'~ ~'.:. I+I:T. • ~~~ ~ ♦ t ` I •♦ , .\ •\•r -...... ex.:.:... vâ.S • ;;,. e ~ ~„ ~r_' ~•:..;r ~C' e t. r ~j.~•• {. -•~;...::'ï'•. ; • r e •♦ •• l• j:••::-•~: :1,~i~ • 1-•p '- ~ ♦ . I ~ I : . ; ';,.-,.,.^::;1!... ' yi 9~ ~ ••• ♦ 1' .. \ w• , ~•I~T• 111 :-Z ~ e ~ t . 4-.•i y3.G :.'• •I I • ~~ • ♦ ♦ e \ . `~~ i ,•i ~ e I r ~ IV . ~ • r . .•• re'~• ' • ► • i • ••• •: • • ! e = 1I ,~ \ ~~ • 1 0 \o I I ~ .•• ' ~ 1 e A, • dAt ._ i. I • . o.I ••• lee i : ~•~ t • ~ . . s. ~• .1 • .:~ • ~ I• ♦ .e 0 I ' \ • ` e - • ~ • • •~ \'1 •:::: ~:+•a4 ~ 1 ♦•• o • r l I •0 1. C a i e • e l t ♦ . r r ` r I , o•s r• re .'•°. I. •••• e o e / • o .. # . 1 er • 1 t. ~ 1 1 1• 1 • . 110.1.8.0 oommimm.•••.-..••

LEGEND

~ 'a! i•rima-zLaavrrE DIP SECTION 3o-•.o%Hcr$a-:LWElarra OF <~ t4S:nKoS:iG LAC TIO ILlV1ER1 T t DEPOSIT sCAi,:: i`-6o01

Fig, 3.5 Percent Pe in hemo-ilmenite concentrates of geological section LM.

1 K

o o o o 0 0

~ 1.000

`~....~ •••. .1•11••• Mim, T-67-2 `- -- -- •••!fi•91-4 .., .c 7-83-i .. V ~Ç Q►T SV%Q l~ ^•r-1gQ4 7- 500

.1500

LE:L~D STRIKE SECTION °fo KEMQ-1L1AENITE > 70 a4' 30-70% MEMO-1LMENITE LAC T dO ii L€ta x ra DEPOSIT p,NOR T aOSiTE seAt.E, 1~~ zoo'

LAKES

Fig. 3.6 Percent Fe in hemo-ilrneni.te concentrates of geological section JK.

- 2 ` • • • I I ~ . ( S^ ~ C' ^ J..frj 712 ~ • • •~ •:~.:•: ...:`.+~~f r•:-: ~•~: ,i . r'-• Z I.~ ~Y: - •~ ~~u~~ ` - .. 'ti:':•:.:: `K' `: ••~~.: -.`• e' `3 `'~~ • 1 Ol • 4 i'wr1 ~♦•r♦-1 ; • ♦ '~ ..... ~•~~ ~ Y.79./, T79:7 P,-ese~~ Sur 4ce_ / / ..• • y♦ • 1 • a • -~Tri ~ T- ;7 ~j ~ ~~ ~. ~ ~ .. y+ ~ 7•$3•S ~ / 1 t - ..... , . 4. ~`♦ . ~=33-9 . ♦ .. • + 1 ~ a , ♦~ : . :: T .^i7•> T'E?'a ~ ." . ♦ i I' ' . / ~ , , .2...... : :ti:' 2 z9 ~~7 — - s • . ""!' ` • ~ 24.....4..3s.11 1 a .. • c:;~ï:.:;: v:::} 35 ~~ • ~~.'~ . • \+~ • l- l \ i . /~ 7•,,, Sl1Q ♦ : • • / . ~ 1 ~.~9 4• ~' ~ ~4 ~~.' '`~' ~ •: ' \ • SI', ~ .~ \ ~~ ~ / •,..... ~+:.....:: ~' ' ~- - • ~ ♦ ‘,• . :•. 2.43 ) ♦ • ♦~~`;:: ?.c~ A 1 .~! l r •• ' • \ '~::~.~0 1 ~ if ' • ~'• • ♦ • , ♦ .` . r~(.i '~ • I a % ♦ • +/ • • ‘ l • , ~ ~ / ♦ • • ~ '72S',—'• :j*V..... ~::

JQ 0 ••/ i`,•` ♦ ~` i, ?^.2%L. ~: +•~ `y. .. .~ • ~ .'''....I. ~, '~L'Z.~~ \•-•••''." •• \•` • i• .I. • • r t I ...`. /" I 1 • ~ / • \ \ --~ ~ ;~;~. $4,...... 4...:4:::::::&• / - + / ~ ~ ~ _ • •~ . • . ~ l \ •i I ~ - • , i - y \ . / a / / • ~ .• \ ~ 1 • - •\ . + ' ~ , • • \ el •+ I • • ; / 1 • ♦ • l , a L. • • ir / 1/ • . . 1• .. 1 •• • 1 • 11 r1 • .

LEGEND

~ 7• 70% ~.a~0-!LF ;_a:sTE DIP SECTION s'vivio ~;;.4?O-il Q2El4iYF OF .:.~ A.glciliiO~:TIS- LAC. T IG ILMENITE DEPOSIT SCALE t': Goo'

-Fig. 3,.7 Percent PTO in hemo-ilmenite concentrates of geological section LM.

A.1

~ i 0 o 0 o 0 Ô 7 1,000

-. . - ? ~ Cv ` ~..**1` .....—. ~ am!,....r _ ~- ~ .... _ 7 71- ••• T-54-1 T-67-2 8 T fl3-1 ~ ~ ...... ~s ~ 75 .2J ~T-7g -5 ~ ~ i-,1-4 . ; / L. t~nn+iA — 4 _1_-- ` ~ sr...:.:22p a •n.C^nT. —..~.~,,.—..:.:.... Gable n•r.97 F r~ Y~~ 7-7 r t ~ :_ :'.~Lÿ : t•0$tl-`~-r~ ... :C`. '2.42 `` `.t.i) —._.~;~•.•::. . ô1::...... :-:.•... .~• ''zr--l~ b, .:::;'•':*:::::":::: 2 ~\ • ~ ~ ' t.-- •1:~.4.+4.::.•:. 47' + • Sno i 'i. l .~ t .=..~^_.~,~~v.• L~~-.r. r ~~- \ ~ d I~t- I _'~ ~_:. 2.35~7: .L 1 1 j; •:♦:• "1'6... ' ••` ~ S • ~ 1 \ • / ` / -,l' ~ / `• `1 ~ ~ ;' i `~t• •;:::. : ,ti,~ 1 "'s • ',of e :.: za~1 '~~~ ® .J ...... : ~ :::. ~ 1 . ~ t e 1 i 1 i I \ f / - ~ - ' : ~~ : ~•: : : .; :•: :•.; ;.::::: y w \ . f• \ 1• ! r %•• :: .~.::.: ~:. 2~fif - t ♦~ t t .:::•~1.!..• i+ ~ ' / \ 1 +.'f ~ 1 ! `~• • ••': # ' # ~•% ~/ ~l # . ,# / 1 ;•~ , ~2+~ï` .-, ;n1:1'7,.•-• ...% \ \ . ~ ! 1 i ~ i ~ , i ~ t II ~ $ I - t e % } - I • . t., ~ ! 1• = I ~ `~ o - ~ . . . ~ 1~ . / / r.• I .. / I — ► / ~ • - t' I +- I 1 • ~ \ • N. / ~ -'500

LEGEND STRIKE SECTION > 70°fo F1EMC.-11.MEN!rfE 4F SO?O % HEf:SO-ILM:ENITE LAC TIO ILMENITE DEPOSIT

.• -♦ . A :oRYKOStTE SCALE I~s 60'6. LAKES

Fig. 3.8 Percent 11g0 in demo-ilrienite concentrates of geological .?ection Jr.

mm....,- .a•z*.iMMWMMMsMsa+wMM.rr 94

*re can conclude that the variations of hemo-ilmenite chemistry are small and do not appear to vary systematically with depth or laterally.

The genetic implications of this conclusion are discussed in chapter IV.

3.6 Inter-elemenrt Correlations in Hemo-ilmenite

The formula of ilmenite may be more accurately expressed as

(FeMgMn) Tî03 with only limited amounts of Mg and Mn (Deer et al, 1964). Chemical analyses of most ilmenites generally 'eveal variable amounts of Fe203; this is due to hematite which forms above 1050°C a complete solid solution with ilmenite (Pons.iack and Barth, 1934; Nichols, 1955).

The mineral from Lac Tio contains on average 30% by weight of hematite and is appropriately described 6.s hemo-ilmenite following the classi- fication of Buddington et al (1963). Small amourts of A1203, Cr203 and V203 ,are found in the hemo-ilmenite of Lac Tio; crystal chemical considerations and microprobe analyses indicate that these oxides occur principally as substitution in hematite where they replace ferric iron. Similar considerations lead to conclude that Mg and Mn occur as substitution for ferrous iron and are principally located in the ilmenite host. Because the chemistry of the Lac Tio hemo-ilmenite is almost totally defined by the relation + (FeMg)TiO3 = 100%, strong re203 correlations are mathematically imposed on all mnjor constituants such as Fe, Fe0 and Ti02. Examples of such correlations are shown in Figures 3.9 to 3.'--':; ".where i.t is evident that, as the concentration of lee 0 increases, the amounts of Fe0 and/or TiO must decrease. 2 3 2 This negative bias is a consequence of the "olosed array of variables"

(Chayes, 1971). A priori, this correlation may be realize:. minera-

- 2.04 x -1.30 Corr. Coeff. 0.81 Syx = 0.04 O 1.150

O 0 O O 0 0 0 0 00 0 0 0 0

0 o 0.950 O 0 0 CO

0.850

--1_,.., 1 1 1 1_.=1.•••• _... ! __J 1.07 1.09 1.11 1.13 1.15 . .:7 Fe /T102

Fig. 3.9 Corre2ation f Fe/TiO2 With Fe~p03, Fe:.i in menite concentrates,

F. zwasniminaw;timmissmistr ` ~~~+~._~~~li -96-

31.0

30.0

29.0

M 0 N N u- 8-9 28.0

27.0

26.0

28.0 29.0 30.0 31.0 % Fe()

Fig. 3.10 Correlation of Fe0 with Fe203 in analyzed hemo-ilmenite concentrates. -97-

y = 0.53 x 4-22.44 Corr. Co. : f. : 0.64 Syx = 0.49 0 0

39.0

o o 0 0 38.5 0

0 0 O 38.0 ~ 0 O 0 O 0 CJ o 0 0 0

V Q 37.5 0 6 0 0 00 0 ~0 O 0

37.0 - 0 0 0

i i ---1 -~_ --- 28.0 28.5 29.0 29.5 30.0

% FeO

Fig. 3,11 Correlation of FeO ;pith TiO2 in aaal'zed homo-i1menite conctentrates. 42.0 42.5 43.0 43.5 44.0 % Fe

Fig. 3.12 Correlation of Fe with Fe203 in analyzed hemo-il.menite concentrates. -99-

0 y = - I.Oi x+75.38 G COrr. Coeff = 0.175 30.5 O Syx = ,).58

30.0

29.5

0 d ~ e> 29.0

28.5

28.0

42.0 42.5 43.0 435 44.0 % Fe

Fig. 3.13 Correlation of Fe and Fe0 in analyzed hemo-ilmenite concentrates.

- 100 -

y -0,34x447.90 Corr. Coeff = 0.73 Syx = 0.44 0 0

39.0

O 38.5

38.0 O ! O O O O O O O O 0 O 37.5 O O O O O 00 O 0 O

37.0 CO O

I I I 26 27 28 29 30 31 % Fe203

Fig. 3.14 Correlation of Fe203 with TiO2 in analyzed hehia-ilmenite concentrates. - 101 - logically by a change involving principally the amount of hematite in the hero-ilmenite. X-ray diffraction analyses of concentrates having respectively the largest and smallest amounts of Fe203 indicate that they respectively contain larger and smaller amounts of hematite phase (Fig. 3.15). It thus annears that the variation of the amounts of hematite anu ilmenite in the hemo-ilmenite concentrates is the

Principal factor responsible for the negative correlations amongst the major constituents.

In order to circumvent the strong mathematical correlations imposed by the variation of the amounts of ilmenite and hematite in the concentrates, Fe203 was normalized to 30% and the concentrations of all the other constituents were recalculated. In doing so, the correlation between Fe0 and TiO2 was greatly improved. Indeed the coefficient of correlation has Passed from an initial value of 0.61 to 0.97.

Attempts to correlate Mg0 with Fe0 using the analytical data as given in Appendix I were not si:ccessful. Likewise, correlations attempted using the calculated values for 11g0 and Fe0 after normalizing

Fe203 to 30.05 yielded no significant interdependence (correlation coefficient of 0.15), indicating that in hemo-ilmenite of fixed Fe203 content, the i,1rr0 content of ilmenite is not simply related to its content in Fe0 as the formula (FeMg)TiO3 would seem to imply. Pursuing the study of the correlation of 1'1r;0 and Fe0. the amount of TiO2 in the hemo--xlmenite which carries a much smaller analytical error than

Fe203 (Table 3.3), was normalized to 37.9 and the calculated values

for I•Ig0 and Fe0 platted. This process yielded a correlation coeffi-

cient of 0.50, suggesting a weak correlation, between MPG and Fen. 31.9%Q Fex03

'Or

Fig. 3.15 (104) hematite a,id .imenite reflections for samples containing respectively 31.9 ani 26.2 percent Fe203. Continuing this study on the distribution of NgC., the author construc-

ted diagrams correlating the WO content of hemc.ilmenite with the

amount of gangue minerals in the originel samrle. This work indicated

that MgO increases nronortiona]ly with the grade of the ore.

In summary of this work, it may be said that the :-1g0 content

of hemo-ilmenite has a weak negative correlation with the amount of

Fe0 in the mineral and also, is positively co'relate,d with the grade

of the ore. These findings agree with an observation we described

earlier, namely, that hemo-ilmenites from the lower grade portion

of the orebody contain lower M ;0 and higher Fe0 than her,-•ilmenites

from the higher grade or massive portions o' the orebody (Fig. 3.7,

see also Annendix III).

It is evident from this study that MgO and Fe0 in hemo-

ilmenite are not conditioned only by the availability of these

constituents. A factor that most likely played a vital role in the

distribution of Mg0 and Fe0 in the ore is the nartitioning ^f these

oxides between hemo-ilmenites and nleonaste. sninels. Because both

these minerals contain varying amounts of Fe0 and Fe201, oxygen

fugacity in the melt undoubtedly was an important parameter control-

ling the r. artitioning of Fe0 and Mg0 in hemo-ilmenites . It appears

probable at this stage, that a study of the cleonaste soinel in the

samples :studied would shed more light on the distribution of MgO

in hemo-ilmenite; however, such work is not in the scope of this

thesis.

3.7 Synopsis of Hemo-ilmenite Chemistry

The chemical analysis a_ 48 hemo-ilmenite eo .centrates,

~~~!OnigiMUMININIMIC ieuriomasannumemrimminriarminirMilltarlffill11111M MIIIIIWAIMEMEREIEMENIMMINMINIIIIMINNIssueseivaitaimimustinea

representing the entire Lac Tio orebody, has shown that the average

hemo-ilmenite contains : TiO 2' 37.9%; FeO, 29.1%; Fe203, 29.2%; MgO, 2.21% and V205, 0.410. Other oxides such as Cr203, .4nO, CaO, Al203 and SiO 2 are found in the concentrate, but together they.constitute less than one per cent of the concentrate. Traces of S, K, Na,

Co, Ni, Cu, P and Ga have also been detected in the hemo-ilmenite

concentrates analyzed in this investigation.

The principal conclusions frac this geochemical study are

as follows :

1. Hemo-ilmenite from Lac Tio is largely homogeneous in composition

throughout the orebody. A few exceptions occur in regions of low

grade ore (30-70% hemo-ilmenite) waiere the contents of FeO, Cr203,

knO and. Si02 are higher and those of Mg0 and A1203 are lower.

No other compositional trends coula ue detected within the orebody.

2.The local variations of the Fe/'Tî02 ratio in the deposit can

probably; be attributed mainly to the varying amounts of ilmenite

and hematite n1-ases in the ore.

3.In general, Lac Tio ore cannot be ungraded above 96.2% by physical

means, since c.omoonertts such as MgO, V205, Cr203 and several others

are held as solid solutions in the hemo-ilmenite structure.

4.Generally, the Mg0 content of Lac TiJ ore cannot be lowered below

2.21% by physical means.

5.Comparing the analysis of the hemo-ilmenite standard prepared

(Table 3.2), with the analysis of an 87% grade ore (Table 1.4),

one notes that at lcest 4/5 of the Ni, 3/5 of the Co and 1/2 of

the Cu occur as atonic substitution in the hemo-ilmenite structure.

The remaining amour is are most likely located in the small amounts - 105 -

II of sulphides present in the ore.

6. it is interesting to note that 2/3 of the gallium occur as a solid

solution in the hemo-ilmenite. The remaining 1/3 is mainly associated

with the pleonast_ apinel where it constitutes anaroximately 0.1%.

7.Most of the Si, Ca, K, Na and S revealed by the chemical, analysis

of the concentrates is associated with small amounts of minera-

logical impurities such as antiperthitic plagioclase, tyroxene

and pyrite. These elements are thought not to Participate in the

crystal chemistry of the I,ac Tire hemo-ilmenite.

8.Considerations on the partitioning, of MgO and re0 in the ore,

leads us to believe that Le conditions of crystallization of

hemo-ilmenite, principally the oxygen fugacity :in the melt, varied

locally during the formation of the orebody.

wiltakeNEREMEMOMPAIII~1~;'~ io6

CHAPTER IV

CERTAIN ASPECTS OF THE PETEOLOGi AND ORIGIN OF THE LAC TIO DEPOSIT

4.1 Introduction This last chapter proposes to review briefly the various theories advanced by previous investigators on the origin of the Lac

Tio deposit and to discuss, in the light of our study, the implications of certain mineralogical and chemical features on the genesis of Tthe ore.

4.2 Metallogenic Traits of the Lac Tio Deposit All of the economically important deposits of Fe-Ti oxides in the general Lac Allard area occur in close association with gabbro and anorthosite rocks. Such an association is but one example of several similar associations throughout the world. In fact, the common association of Fe-Ti oxide deposits with rocks of the anorthosite kindred

(anorthosite, gabbro, gabbroic anorthosite, etc.) has led most geologists to postulate a close genetic relationship between the oxides deposits and the anorthositic rocks enclosing them.

Much research and data on anorthosite and associated Fe-Ti oxide deposits has been done in the last decade. As a result of this, geologists tend to consider anorthosite and related rocks as a result of igneous differentiation; there is still however, much controversy on the nature of the parent magma, the process of anorthosite derivation and on the mode of origin of the oxide ores associated with them

(Isarksen, 1.968).

107

, „ Most workers on anorthosite generally accept the view that V Fe-Ti oxides ores are magmatic in origin as opposed say, to hydrothermal

or metasomatic origin. Hammond (1952) considered the Lac Tio deposit as having formed from an ore magma and that hydrothermal activity played

no important role in the formation of the deposit. His conclusions were

based on the following observations :

(1)The presence of sharp contact!; between massive ilmenite and unaltered pure anorthosite.

(2)The presence of unsupported inclusions of unaltered anorthosite within the massive ilmenite.

(3)The general absence of minerals such as muscovite., garnet, tremolite-actinolite which are commonly

associated with hydrothermal deposits.

(4)The uniformity of mineralization which suggests

an approach to equilibrium conditions.

(5)The orientation of platy ilmenite crystals parallel to the e_,titude of the ore sheet,

suggesting crystal settling in a liquid.

The Lac Tio deposit displays striking similarity to certain hemo-ilmenite

deposits in the Province of Quebec and in particular to the Brulé Lake

hemo-ilmenite depo:lit in the Labrieville anorthosite massif (Anderson,

1963, 1966). Both deposits occur as gently dipp::ng tabular bodies of nearly massive hemo-ilmenite in anorthosite. The anorthosite host rock

of the Lac Tio deposit (cf. section 2.2.2) and that of Brulé Lake

with accessory deposit consist of antiper,hitic andesine (An45Ab600r5) amounts of hemo-ilmenite platelets and minor ferromagnesian minerals. AI:: AINUMEr MIIIIIIKOMMIMMOI

108

Such an anorthosite is classified by Anderson and Morin (1969) as an

andesine type anorthosite as opposed to a labradorite type anorthosite.

Both deposits display field relationships suggesting that the material

making up the deposits was injected into the anorthosite, and thus

would appear paragenetically late with regards to the anorthosite

itself. At Lac Tio, the injected nature of the hemo-ilmenite mass is

mainly shown by the presence of unsupported large blocks of anortho ite

in massive hemo-ilmenite, the sharpness of the contacts between the

ore sheet and the anorthosite, and in the upper part or layered portion

of the sheet, by the ;presence of numerous small anorthosite inclusions

in the hemo-ilmenite rich layers and the presence of crushed and bent plagioclase crystals in the disseminated ilmenite layers (Lister, 1966).

These features have led Hammond (1952) and Lister (ibid) to consider the Lac Tio deposits as having crystallized from a Fe-Ti oxide magma

injected into a gently dipping shear zone in hot anorthosite. Although

Lister (ibid) does not specify the mode of origin of the ore magma he emphasized that the magma was not derived by filter pressing of the

anorthosite. As evidence for this he cites the much lower V, Cr and Al

contents and higher Mn amounts in the host rock hemo-ilmenite as compared

to the hemo-ilmenite in the ore sheet. The trend of trace element variation in ilmenite and magnetite

with progressing crystallization of igneous magma is presently fairly

well established. The ctudieE of Vincent and Phillips (19510, Schwelluus

and Willemse (191+3), Caty (1970), Lister (1966) and Anderson (1966) show that the V, Cr, Al and Mg contents of magnetite and ilmenite decrease with progressing crystallization differentiation whereas their 109

Mn content increases. In light of these data, tbs lce er V, Cr and Al content and higher Mn content of hemo-ilmenite in the anorthosite host

rock, compared to hemo-ilmenite from the ore sheet would indicate that

the hemo-ilmenite in the anorthosite host rock formed from a liquid

that characterized a more adver.zeit stage :f differentiat - than that

of the liquid from which crystallized the hemo-ilmenite the ore

sheet. Indeed, the high Mg and Al contents and the uniformly low Mn

content in hemo-ilmenite from the Lac Tio orebody may be considered as

a good indication that the oxide magma that formed the orebody exited fairly early in the crystallization sequence that gave rise to the anorthosite kindred rocks that underlie the general Lac Allard area. Concerning the origin of the Lac Tio deposit we therefore

concurred with the views expressed by Anderson (1966) on the origin of

the Brulé Lake deposit, namely that, although the Lac Tio deposit

appears paragenetically late from field relationships, its chemistry

supports the idea that the oxide magma formed early in the paragenesis

and subsequently was emplaced or injected in relatively younger andesine

anorthosite rocks. Considering the growing amounts of field and labo-

ratory evidr;nces in support of the immiscibility of Fe-Ti oxides liquids and silicate liquids (see in particular, Philpotts, 1967), we visua'.ize the oxide magma that formed the Lac Tio orebody as having

separatsd early from the silicate liquid by liquid immiscibility. The

oxide Liquid may have settled at the floor of the magma chamber to be

later injected into overlying andesine anorthosite. From this liquid,

crystallized hemo-iimenite, pleonaste spinel, and small amounts of

apalite, iron sulphides and corundum. •~. 110

,4.3 Crystallization and Evolution of the Hemo-Ilmenite Magma

Concerning the crystallization of the ore magma, Hammond (1952)

and Lister (1966) considered that the orientation of the homo-?lmerite

crystals subparallel to the walls of the ore sheet indicates that crystal

settling took place during; crystallization. Indeed, the discoidal out-

line of the hemo-ilmenite, their subparallel orientation and the "inter-

cumulus" texture shown 'ny the accessory minerals, in particular the pleonaste spinel, are strong indication that crystal settling took

place during the crystallization of the oxide magma. By analogy to

minerals in stratiform or layered complexes, the hemo-ilmenite crystals

may conveniently be described as a cumulus crystal, and the ore as a

cumulite. Contrary to Lister (1966? *whose analytical data suggested

a trend of decreasing V and Cr content and increasing Mg content in hemo-ilmenite upward in the massive section of the ore sheet, our study

indicates that there is no systematic variation of trace element across,

the overall section of the deposit. Indeed, all attempts to correlate

the stratigraphic position of the samples studied with their trace element content failed to reveal any systematic trend. The absence of

a trend in the trace element content of hemo-ilmenite that have largely

accumulated by crystal settling from the oxide magma may appear somewhat contradictory. A possible explanation for the lack of systematic trace element fractionation over the entire stratigraphic height of

the deposit may be that the consolidation of the deposit did not proceed

through the simple and continuous crystal settling of hemo-ilmenite from a single volume of oxide magma approximating the present volume 111

of the deposit. Rather, to explain the homogeneous composition of the deposit and the absence of large scale variation in the distribution of Mg, Mn, Al and Cr, we suggest that the Lac Tio deposit was formed by the crystallization of repeated injections of essentially identical oxide magma into a zone of dilation iii hot anorthosite. The occurrence of other hemo-il.menite deposits in the Lac Allard area may add some support to this hypothesis. The injection of new magma into the zone of dilation would, by intermixing with the crystallizing magma, dilute or homogenize the liquid and mask the fractionation trends which might have existed between the settling hemo-ilmenite crystals and the liquid. According to this model, fractionation trends may be present over short sections of the deposit, however, no regular trend would be apparent, when trace elements are studied over the entire section of the deposit.

Except perhaps for small amounts of volatiles, mainly water, which might have escaped or diffused into the country rocks during the crystallization of the oxide melt, we envisage, similar to Hammond

(1952) and Lister (1966), that the oxide magma had a composition identical with that of the present ore. From this liquid crystallized hemo-ilmenite crystals and accessory amounts of pleonaste spinels, iron sulphides, and rarer primary magnetite, corundum and apatite. The lack of data, on the specific gravity and viscosity of the oxide magma and on the rate of growth of hemo-ilmenite necessary for the crystal to reach a size where crystal settling would commence, renders highly qualitative the aescription of the crystallization of hemo-ilmenite from the melt. It would appear probable however, in view of the rather low viscosity of molten Lac Tio ore (1) that relatively small crystals, possibly millimeter size, could grow from the liquid and settled to the floor of the chamber. Under slow crystallization, the precepitated hemo-ilmenite crystals could continue their growth by interchange with the interstitial liquid and with the overlying magma. This process of "adcumulus" growth (Wager, 1963) resulted in centimeter-grained hemo-ilmenite crystals, having the characteristic discoidal or pellet outline and interlocking boundary shown by the Lac Tio hemo-ilmenite. Adcumulus growth of precipitated hemo-ilmenite crystals was probably an important factor in reducing the fractionation between crystals and the overlying liquid. The extent to which this process could operate cannot be evaluated at this time because of the lack of data on stratigraphically closely spaced samples. It would appear improbable, however, that the homogeneity of the entire deposit could be explained by adcumulus processes alone.

The distribution of accessory minerals in the ore, mostly interstitial to the hemo-ilmenite crystals, suggests that these crystallized last from trapped or "pore space" interstitial liquids. The fact that the sulphide minerals are more or less randomly distributed in the ore tends to support the idea that their abundance was largely controlled by the amount of trapped interstitial liquid.

The relatively narrow compositional range of hemo-ilmenite

(1) Research carried out at the Q.I.T. research center at Tracy, Que. on the viscosities of ore and slags indicates that molten 90% grade hemo-ilmenite ore from Lac Tio has a viscosity of 15 ceutipoises at a temperature cf 1440°C. Although the viscosity of a natural oxide magma at temperatures 8f 1000 to 1100°C is probably much higher than that determined at 1440 C, this research suggests that viscosities of oxide magmas are considerably less than that of silicate £)agmas. 113

in the Lac Tio deposit suggests that the conditions of crystallization

remained fairly uniform throughout the crystallization of the entire

deposit. The oxygen fugacity of the ore magma was probably the principal

factor that influenced the composition of the hemo-il;anite. We believe that local variations in oxygen fugacity, principally due to gradients

established during the adcumulus growth of the settled hemo-ilmenite

crystals, controlled the partition of Fein and Fe203 between the hemo- ilmenite crystals and the interstitial liquid from which principally

crystallized pleonaste spinel. As discussed, earlier in this study., the variable Fe0 and Mg0 contents of the hemo-ilmenite are probably

related to such variations in oxygen fugacity.

Our study has shown that primary magnetite is almost absent from the Lac Tio ore. Indeed only one of the samples studied contained

accessory amounts of primary magnetite. This suggests that the crystallization of the oxide melt proceeded under uniform and fairly oxydizing

condition. The crystallization of small amounts of primary magnetite

probably arose through fluctuations of oxygen fugacity in the inter-

stitial liquid during the adeumulus growth of the settled hemo-ilmenite crystals. Primary magnetites appear to contain very low amounts of

TiO2 in solid solution. Microprobe analyses of some magnetite grains indicate a content of approximately 0.2% Ti (equivalent to 1% ulvo-

spinel) in the magnetite. Hargraves (1962) also reported a content of

0.5% TiO2 in magnetite from Lac Tio. Lister (1966) also reported low TiO 2 contents in magnetite from other deposits in the Lac Allard Area from which he inferred equilibrium temperatures of 550°C and oxygen

fugacity (Logf02) less 10-17. We believe that these data do not define

accurately the original conditions of formation of the deposit but 114

indicate certain intermediate conditions that prevailed during the cooling of the oxide mass. It is considered probable that the very slow cooling of the hemo-ilmenite body favored the migration of the ilmenite out of the magnetite, thus leading to a low estimate of the temperature and oxygen fugacity of the oxide assemblage.

4.4 Subsolidus Evolution of the Hemo-Ilmenite

Upon cooling of the oxide mass, the original high temperature hematite-ilmenite solid solution intersected the solvus of the Fe20 3- FeTiO. system. According to Carmichael's (1961) data on the hematite- ilmenite solvus (Fig. 4.1a) the unset of exsolution for the Lac Tio hemo-ilmenite took place at temperatures in the neighborhood of 800°C. With continuing decrease in temperature, the composition of the unmixed ilmen-hematite and ferrian ilmenite phases changed composition along the limbs of the solvus, becoming respectively poorer in ilmenite and hematite. The composition of the unmixed phases of the Lac Tio hemo- ilmenite was discussed in section 2.2,1.4. X-ray diffraction analyses and crystal chemical considerations indicate that the xematite phase retained approximat,ly 14% ilmenite in solid solution whereas the ilmenite phase would appear to have retained very little hematite in solid solution. Indeed, the smaller lattice spacing of Lac Tio unmixed ilmenite compared to pure ilmenite may be explained as almost entirely caused by the effect magnesium in solid solution in the ilmenite. The

composition of the hematite phase of the intergrowth agrees fairly well

with the composition to be expected from Carmichael's (1961) solvus

(Fig. 4.1a).However, Carmichael did not take into consideration the IMOMNINERIMMINIMENIMINEMBAVIIIIIIMINEMEIRMIRMEMLIERIEWIRIBMIIIIta~.®

115

Amato Loc Tio HFmo - Il menite ) °C 1

re tu

a Nei er Temp

200

0,4 LO 0.8 0.8 FeT103, Mole fraction Fe203 • Fig. 4.1 (a) — Solvus curve for the hematite-i meriite system (modified from Carmichael, 1961).

A Fe203 FeTiOa

Fig. 4.1 (b) — Schematic diagram showing the extent of solid solution at low temperature in the NgTiO3 — FeTiO3 — Fe203 sy stf i1. Line AB represents the Lac TiO binary system. u6

effect of Mg on the solvus; our data suggest that the effect of Mg

decreases the solubility of hematite in ilmenite. For an ilmenite

corresponding to (Mg12Fe88)(TiO3), our data suggest that the solvus lies close to the ilmenite side of the system. A schematic diagram

showing the possible subsolidus relationships at low temperature in

the ternary system MgTiO3 FeTiO3 Fe203 is shown in Fig. 4.1b. The

field of solid solution is shown as stippled in the diagram. Subsequent to the exsolution of the hemo-i.lmenite,subsolidus

reactions produced small amounts of secondary magnetite (Cf. Fig. 2.15a, b) and secondary anatase (Fig. 2.19a, Although the strongest diffraction

lines of rutile Piave been identified in some powder diagrams from con-

centrate enriched in secondary magnetite, the commonest form of TiO2

associated with secondary magnetite is anatase. The nearly constant association of anatase with secondary magnetite (Cf. Fig. 2.15b) strongly

indicates that the two minerals originated through a reaction involving

hematite and ilmenite. Textural observations suggest that secondary magnetite and

anatase may be related through a reaction,'as follows :

(a) 6Fe203 = 4Fe304 +02 (b) 4FeTiO3 + 02 2Fe203 + 4Tî02

Combined reaction : 3Fe203 + 2FeTiO3 = 2Fe30 + 2TiO2 + Fe203

This reaction would lead us to conclude that the unidentified iron-rich Am surrounding anatase (Fig. 2.19a) may be secondary hematite. The

common development of secondary magnetite and anatase along fissures

and cracks in the hemo-ilmenite suggests that circulating fluida Q probably water, induced the breakdown of hematite to magnetite. Similar observa-

tions have been made by Kretschmar (1971). The oxygen liberated in this INIMENM ME

117

reaction in turn oxydized the ilmenite to anataae and hematite. We

believe that the secondary magnetite and anatase were formed at rela-

tively low temperature. Experiments on the oxydation of Lac Tio hemo-

ilmenite at room pressure indicate that rutile and hematite are reaction

products at 900°C; at higher temperatures, rutile and hematite react

to form pseudobrookite (Archambeault, .1953).

4.5 Conciudirg Statement This investigation has shown that the Lac Tio hemo-ilmenite

deposit is, in general, mineralogically and chemically fairly homogeneous (Chapter II and III). A review of the literature on some Fe-Ti oxide

deposits together with the results obtained in this study has enabled

us to consider a model which attempts to explain the principal features

displayed by the Lac Tio deposits. The principal conclusions concerning

the origin and evolution of the deposit are presented below in para-

genetic order.

1. The oxide magma which gave rise to the Lac Tio deposit formed by liquid immiscibility at an early stage of differentiation

and was subsequently emplaced by repeated injections into younger

solidified anorthositic rocks.

2. Upon emplacement and during the influx of new oxide melt, the oxide magma was subjected to crystal fractionation whereby htmo-ilmenite

crystals sank to the base of the zone. Slow cooling is believed

to have favored conditions for pronounced adcumulus growth of the precipitated crystals.

3. The conditions of crystallization remained fairly uniform

throughout the solidification of the entire deposit. However, local variations in oxygen fugacity probably controlled the

partition of FeO and Fe203 between the hemo-ilmenite and the

interstitial liquid which principally crystallized pleonaste

spinel. Only locally did small amounts of primary magnetite

crystallized from the interstitial liquid. 4. After solidification and at temperatures in the neighborhood of 800°C, the high temperature hematite-ilmenite solid solution

intersected the solves of the Fe203 FeTiO3 system and unmixed

to ferrian ilmenite and iimen-hematite. The hematite phase

retained some 14% Mol. of ilmenite in solid solution whereas

the ilmenite phase exsolved most of its hematite. Subsequent

to the exsolution of the hemo-ilmenite, local subsolidus reactions involving hematite and ilmenite produced small amounts

of secondary magnetite and anatase. - 119 -

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Schwellnu' C.M. and Willemse J., 1943; Titanium and vanadium in the magnetic iron ores of the Bushveld complex; Geol. Soc.S.Africa Trans. 46, pp. 32-38.

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Wager L.R.,,1963; The mechanism of adcumulus growth in the layered series of the Skaergaard intrusion; Min.Soc.Am.Spec. paper no. 1, pp. 1-9. The author sincerely appreciates the advice and assistance given by Professor Gaston Pouliot of the Department of Geological

Engineering who directed this study.

The author wishes to express his thanks and appreciation to the directing personel of the Quebec Iron and Titanium Corporation for authorizing this study and making available all departmental facilities. In particular, the writer would like to thank Dr. G.G.

Charette for his assistance in reviewing chapters I and IIIof this work. The author also acknowledges with gratitude the help received from Dr. F.D. Leipziger, Head of the analytical section at the

Kennecott Laboratories in Lexington, Mass. Special thanks are also extended to J.J. Hill for his care and skill in providing the electron-probe analyses required in this study. Sincere thanks and appreciation are expressed to Dr. A.N.

Mariano for his helpful suggestions in the study of the sulphides and

spinet and for ,droviding all of the color microphotographs contained

in this thesis. Parts, of this research were rendered possible through grant

no. CR-251-71 of the Geological Survey of Canada. A P P E N D I X 1

preparation and Chemical Analyses of Hemo-Ilmenite Concentrates from Lac Tio Ore

Analyst : Quebec Iron and Titanium Corp. Research Center, Tracy, Quebec, Canada. - 126 -

Preparation of Hemo-Ilmenite Concentrates

A total of 48 samples were selected from a group of 2100 core samples obtained from the 1966-1967 drilling survey. The sampling procedure in use at that time consisted in cutting the cores in lengths of

10 feet, splitting the cores longitudinally in half and crushing one half of the core to -6 mesh and storing the crushed material into one pint cans. The procedure used to prepare the concentrates of hemo-ilmenite required in this study is as follows :

1. For each of the 48 samples selected, a representative sample was obtained by splitting the material stored in the one pint cans. In each case, enough sample ':a.s taken to fill an 8 oz. bottle.

2.Each sample was ground between 150 and 250 mesh, in a cast iron ball mill. Screening was carried out with Tyler screens.

3.The -150 +250 mesh fraction was washed and dried at 150cF for 12 hours. k. Similarly to the procedure used in preparing the standard hemo- ilmenite sample (Appendix II),each sample was treated with tetra-

bromoethane to separate the fel:dspers and - me of the micas. The

samples were washed with methyl alcohol.

5.The highly magnetic fraction of each sample was removed with a hand magnet. The remaining minerals were separated using a Stearns

high intensity magnetic separator.

6.Each concentrate was ground under acetone to -325 mesh in a shatter box, and stored in k oz. bottles. Sample weights varied between 30

and 300 grar,.s . -127-

The 48 concentrates were divided into twelve groups of four samples for chemical analysis. As a control, a sample of the hemo- ilmenite standard (cf. Appendix II) •gas inserted in each group to be analyzed. l

Chemical Analy^es of Remo-ï]menites

Sample 392 221 588 554 609 no. 2127 2199 839 1139 2150 98 119 139 280 ~ r ~ 37.0 37.2 ( 37.5 " 37.7 38.4 39.4 37.9 TiO2 37.7 37.6 38.1 3 8.6 37.4 37.5 36,7

27.9 28.0 29.2 28.7 30.1 30.6 29.8 Fe0 30.1 27.,5 28.8 30.1 29.4 28.0 28.9 . r ...._.. 30.6 30.5 28.9 29.3 26.9 26.2 28.2 Fe203 28.2 31.9 29.3 27.2 28.0 30.7 .27.6 c alc. ----,--- 0.19 0.21 0.25 1 0.23 0.24 0.23 0.24 0.20 0.21 A1203 J 0.18 0.20 0.17 0.33 0.21 ! i 0.37 0.41 0.40 0.41 0.41 0.41 0.40 0.40 0.40 3/205 , 0.41 0.41 0.41 0.42 0.38 . ._..._. . . 0.11 0.10 0.10 0.14 0.08 0.13 0.06 Cr203 0.24 0.10 0.10 •0.09 0.17 0.08 0.06

~ 2.20 1 2.08 2.02 2.35 2.43 2.01. 2.42 2.12 2.35 2.16 - Mg0 11.58 2.24 2.43 222.

0.16 0.16 0.15 0,16 0.16 0.17 0.17 Mn0 0.20 0.16 0.16 0.16 0.17 0.17 0.17 _ ' _,_.r._._,_.,,.. •__..._ 0.10 0.10 0.10 0.10 0.10 0.10 0.11 CaO 0.10 0.10 0.10 0.10 0.12 0.11 0.12 r 0.26 ------•- -- Si07 -0.53 0.17 0.15 0.18 0.51 0.12 0.29 . ~~ i_ ~

Chemical Anal,'scs of Iiemo-1lmenites sample 207 522 867 510 452 253 569 531 no. 674 620 366 292 259 231

37.9 37.9 37.6 38.2 37.8 '37.3 Ti02 37.4 37.9 37.4 37.5 37.6 38.2 37.8 38.0 I .., 29.2 28.2 29.2 28.5 28.5 28.9 28.8 Fe0 27.9 28.8 29.3 29.8 28.3 29.1 28.4

29.3 29.7 29.5 29.0 30.2 Fea 03 31.0 29.3 28.6 28.0 29.9 28.9 30.0 29.0 30.5 calc. 0.28 0.22 0.21 0.28 0.2? A1203 0.21 0.21 0.~.4~ 0.24 0.32 0.232 0.19 0.35 0.23

0.46 0.45 0.46 0.47 0.44 0.41 0.40 0.41 0.37 0.41 0.45 V205 0.41 0.43 0.39

0.08 0.08 0.09 0.09 0.10 0.10 0.13 Cr203 0.09 0.09 0.10 0.08 G.08 0.10 0.15

1.98 2.30 2.48 2.28 2.19 Mg0 2.22 2.27 2.33 2.25 1.78 2.46 2.42 2.21 2.47

0.17 0.17 0.17 0.16 0.16 0.16 0.16 Mn0 0.16 0.16 0.17 0.17 0.18 0.17 0.17

0.1G 0.09 j 0.11 0.11 0.10 0.10 0.11 0.13. 0.11 0.10 0.10 Ca0 0.11 0.11 , 0.10 , !

.-- ______Sica -_-_ __ __ ------)

Chemical Anal7ses of Hemo-Tlmenites

1228 Sample 1072 :1164 1173 1242 1289 1350 1199 no. L498 504 687 705 911 11006 s. 37.4 37.7 36.7 38.3 39.2 38.0 37.8 38.6 TiOz 1-39.2 38.0 38.1 37.0 36.9 38.7

------29.4 28.7 29.3 28.3 27.8 29.1 29.6 28.7 28.0 Fe0 30.5 28.8 28.9 28.4 28.2

28.6 30.3 32.2 28.3 27.6 30.0 30.7 28.5 Fe 03 26.9 29.2 29.0 30.7 31.3 29.5 ca~c. 0.32 0.25 0.33 0.23 0.23 0.26 0.22 0.25 0.26 Ala 03 0.21 0.22 0.24 0.26 0.25 L- 0.48 0.41 0.38 0.36 0.41 0.44 0.44 0.37 V2 05 0.41 0.40 0.39 0.37 0.39 0.38 '

0.10 0.09 0.09 0.09 0.17 0.09 0.10 0 09 0.15 Cra 03 0.07 0.10 0.09 0.11 0.08 12.44 2.16 2.17 2.26 2.37 12.19 2.40 2.46 2.23 Mg0 2.32 2.29 2.29 1.78 2.23

I 0.16 0.16 0.16 0.17 0.16 10.18 0.16 0.16 0.16 MnO 0.17 0.16 0.16 0.17 0,16 0.08 0.12 0.10 0.12 0.11 0.11 0.10 0.10 0.08 CaO 0.10 0.10 0.10 0.14 0.11 0.19 0.28 0.18 0.16 0.10 0.16 0.14 0.1.A Si02 0.19 0.44 0.13 Chemical Analyses of Hemo-Ilme:.ites

/ 2172 1313 1348 27.13 2052 2023

38.6 38.5 37.4 38.4 37.4 39.6

29.8 29.3 28.7 29.2 30.0 30.7

28.2 25.? Fe2 03 28.7 29.5 30.5 28.7 calc.

0.18 0.25 0.23 0.23 0.21 0.17

0.37 0.41 0.38 0.37 0.40 0.35

0.11 0.11 0.08 0.12 0.12 0.23

1.70 1.50 MgO 2.07 2.33 2.33 2.31

0.20 rxn0 0.16 0.16 0.16 0.19

0.09 0.07 Ca0 0.09 0.10 0.11 0.09

Si; 0.20 0.13 0.17 0.14 0.52 i i -qansssermm. IIIIINIIIIL ~®

132 -

. .A,PPFNI)IY. II

Prenaration and Chemical Analysis of

an Hemo-Ilrienite Standard

Analysts : Quebec Iron and Titanium Corn. Research Center, Tracy, Quebec, Canada

and

Kennecott Corner Laboratory, Lexington, Massachusetts, U.S.A. - 133 -

Preparation of an Hemo-Ilmenite Standard

The nrocedure used to nrenare a standard hemo-ilmenite sample

from Lac Tio is as follows :

1. A 40 lb. sample of hemo-ilmenite ore was hand-picked on the Q.I.T.

ore pile. The material was selected in such a wayr as to avoid the

gangue and host rock minerals.

2.All the rocks susceptible of containing important amounts of

magnetite (Fe304) were re,iected. This selection was done by

using a hand magnet.

3.The material was crushed to -1/4 inch using a jaw crusher and was

farther reduced to -6 mesh in a cast iron mortar.

4.Tne sample was ground between 150 and 250 mesh in a cast iron

ball mill. Screening was carried out with Tyler screens.

5.The material was washed and dried at 150°F for 18 hours.

6.Most of the feldspars and some micas were separated using tetra-

bromoethane which has a specific gravity of 2.97. The heavy fraction

which contained mainly the hemo-ilmenite was washed several times

with acetone.

7.The highly magnetic fraction of the sample was removed with a

hand magnet.

8.All gangue minerals were separated from the hemo-ilmenite with a

Frantz isodynainic separator and a Stearns high intensity magnetic

separator.

9.The hemo-ilmenite concentrate was f;round in acetone to -325 mesh

in a shatter box and rendered homogeneous by mixing in a ball mill

container for 36 hours. The concentrate thus prepared contained less than l% of mineralogical impurities. Microscopic examination under immersion oil showed that the principal impurities were rare grains of suinels, nyroxene and feldspars. The low amounts of SiO2' Ca0 and PJa20 and K20 reported in the analysis (section 3.3 ) are most likely due to these impurities. We believe that these elements do not narticioate to the crystal chemistry of Lac Tio hemo-ilmenite. ~

Replicate Analyses of Standard Hemo-Ilmenite Concentrate )7

Analysi8 1 2 3 4 5 6 7 8 9 10 11 12 lverage no. ~ ~ ,

Ti02 37.4 37.4 37.6 37.6 37.7 37.6 37.6 38.0 37.6 37.3 37.6 37.4 .37 6

FeO 28.3 28.2 28.0 28.4 28.3 : 28.0 28.2 28.2 28.0 28.3 28.4 28.3 28.2 ' --~-----.----^-~-- Fe2 03 30.2 30.3 30.3 29.7 30.2 30.7 30.6 30 2 30.6 30.3 30.2 30.7 30.3 calc. A1203 ' 0.22 0.23 0.21 0.21 0.23 0.21 0.23 0.23 0.26 0.22 0.24 0.25 0.22

-..-= ~.~.- - 1 • • Y205 0.43 0.41 0.41 0.43 0.43 0.39 0.37 C.43 0.41 0.44 0.36 0.42 0.42

t ~.~...+~ ...... ~... .-~ - {~~

Cr203 0.10 0.10 0.10 0.10 0.10 0.09 0.10 0.10 0.10 0.10 0.09 0.09 0.10

Mg0 2.42 2.47 2.40 2.46 2.44 2.39 2.37 2.41 2.4'2 2.43 2.36 2.38 2.42

Mn0 0.16 0.16 0.16 0.16 0.16 0.17 0.16 0.15 0.16 0.16 0.17 0.16 0.16

Cao 0.10 0.10 0.10 0.11 '0.10 0.10 0.]0 0.11 0.10 0.10 0.08 0.08 0.10

~ - - ------' APPF,NDIX III

Cross-section Diagrams Illustrating the Distribution of FeO, Fe203, A120 and Cr20, 3 in the Lac Tio Orebody

Note: The location of the sections with respect to the orebody is shown on Fig. 1.10 p. 28.

A . ~

T797 iPresert Sur T-~7-9 ~ ~ ~~~ ~,.,•,—..., s~ T83s •, ♦ T-,3-9 T-87.S-~ f.ga ~~ ~ 1~~ J. ♦ • ♦ • :12$•9 j.• ._1N, . • •• ,", .' •, • ~1~' • _ ' ~ *. I 1 • / • . A ; ;~;•, ;;,: ;• ;_:, ~ ; 50Q ( ~'Ji,. •: ~. •••5;1'-•.:~: - :7 :17: • r• • 1J ..?•!.._•.2. .. • ♦ `_-' ` I r • •-- 1' ] a,/ • : I • `i :ti'' '~~• •• ~ ~ 3ô.1 ~??,.'a•~. 11 .' V~ r1•r r• A o ~'i ::•2T.9 --' • •jJ~ ~v•.'`~•JI. ~ar • • 111 1~ 21• r • ;• \ ~` 1 ~ • ~g..~~i~ n ' `~~i 1 I • ~ ? / •. 29.y~ ` :~• • ••`. %`1;1I~•..„%• .Y.11...... ~; ~ I r'1• ~ 1: 1 .~::/ :• ; 130.=?•'%•• . / • 1 1V• ~ _ ; .~•;• ::: 11 .id•— 72:5=>> ~ .; .~ :... 3ô : ,~1 I • je.e 1r . 1 ~ • g 1 ;1~ÿ ~+.•. -_:,2•~' ~I,N • ~}; '::; .:~:'t }~•~ , I 1 I ♦ •♦ ••: 5Qq '1 . ` ~ ~~h~Î / •/ '• ~~~+~ti ~= ?•v':;.;';•: :~:.::: ~ ~ ! 54^ Ar •r~11 I ~.`.• ti•:: ~:*:~.: 1 •./~ a •• r 11 , I. . • :~~•::$ r• vI ~f I 1 i`~' ". •:i::~:;r .•;: :; `:;: ::•:.:':.• .: •.1 , ~ I1 ~ 1 A I 1 ♦ ~ 1`.::.4:• w%.:". ....•.4..:.`I .` -.4:,:-..L w ..V.:? 1 .... r ,„•• I~ r ♦ '• . • ,I ~~•‘ ; / ` ♦ •~ ~ • 1 1 ♦ o ` 1 r • r i I1 • 1 I• r I I ► I• ., 1 1•• i~ •11, • i, • 1 11 . .p A • 1 • • •

LEGEND ~ 70% n;.'-.ht174LA;âWiTk DIP SECTION 30 -70 % 6i F.p.: O• i L.t4 E N ITE OF AN ohi ii031TE LAC TIO ILMENITE DEPOSIT SCALE 1/=600'

Percent FIFO in hcmo-ilmenite concentrate: of r eolocricai section T'- .

I-- .x r o o o o 0 da ~ 1.000

C ? ~" `7...•••• ~ .~ 'ammo ..•T-gJ-4 6 T-67•2 T-71- g C+• ? ~. v7 T4:-9 T- 4-1 ~ T-7g-5 T-83 _ ...R. : •r • c ert-^:. ch. ~,,~..,;':: 30.6 Gvrt T 871 - 2 ~ t.+i;. !!291 ~; -+* 19. ~ _ _ : :.•5 ~• : . 1 t - ~: : r:: _ . ~:1• •l.•:.'~ -L.~• . r~-. i.~i~v::::::~ '•Y.ti•.. wû~~••_? +:. •ji~ • t••1r.Ÿ 500 t~~ • ._ •~{•...___• Fi_ _ __..._-._'^~'r,~•1~+.::_~':••~':~ ~'.•.~..~:•,~~~.~:~:•yJj~%Î: _ ~ ♦ ~ y.:~i ia .:•:•::~ i,[_i_. r 4..4:";;;.:Cr Y • .I?_~ ~~`' 2 • 11e% ' 1~~~•:~27•9i+' 10 \ ♦\ i ~1 ~ ~~ . s, I ♦ ♦ \ ~ 1 # \ ' ~ \ 1 i ~/ ~ ~ I % I.- \ / . \• / ~ r ~ ~♦ I ~ . ♦ 1 i ~ - . I , ~ I \ ~ . ~ / ~ ~ .; \ e • • ~ I 1 ~ • 1 r / 1 I : / 1 ~ \ / / `- ~~: : • ~:::•: :: : :: ® : :::: •,;'% ;t;~:~„ :.,••.;~~ . , , .7"1 - "..7.=% / % t / , \ ~ / ` \ ► - ' ~ / . ~ ! r ~ . I . . / ~ / ♦ I I ' I ♦ ► ~.••I rI .• ~ 1 _ \- • i % - • - I ~ ~. I \ I ♦ / . I 1 J I r _ / 1 .. .. / 1 - ' .___s_ 1400

LEGEND STRwNEE SECTION > 70% ~.cPAO.ILME11tTS O~r 30-70 % H.r••It"~G •• 1L~/,E hllëE LAC 110 Il.4lPENI T E DEPOSIT •,\ . \, AR1ORTitOS1TE SCALE 1~s SsO®` EE LAKES

Percent I'eO in hemo-ilmenite concentrates of ;;eolopi.ca1. section JK. 11121EIMINBINSIRFAMIR

L 4

...... ____-----A .~/••• ' Y'"5rn`I:92•6 I ;• • i.;:::: :C: ~~ svf~n~ 1 % ~:ti:;:: :;::~-'. i <••• ••• T-79-7 — u / • r`,~f:i'~':Jÿ. :~.,~~ r+~?~►••~ , ~ ;64:...%~<'~ :j ` :j%i ~ I ~::•r +' T.79 4.• Preset Sur~ee w • •T• •••.,... `` ..: 1i tr 1 1 • ' .•.t . +• ,•• 1•1 w• • • • ~7 9 ~ ` ..~ .. —c: T.g3•5 T-33.9 . ; It•. ._~..5..•_ T-E7-5 ~ 7-e3-3 w /+ ~• ~ ~/ i` ' • / ~ , / 7..•..:•ti, Fq7 • I • ~ .. • ~ I • + .:•' .• • -.4—. ~ ~'1~••,,• 1 .. r I \ ~ ' ~': • i • ~ i , ~~ ~•~: 0• •, /• 1 ~ •.1 ~'v~'t30.T_}:: r . ~,.?Z 1 L `+ !'`• .~~•..;:: :IZ7.6~; • ~ 1 • • ~'~ : :~ ~ 33.'s ' . r • ~' '•::r~~. . sâ0.6f: ` r • % ~ % I ♦ ✓. , `.r•• • ~ •, I••1 '` .'♦ ♦• I • ' ü•: "::: : t- J.~••.1~ • • I 11 I • • 1 r , ,~::•:~29.5 • • 1' • • .~ •;,:y. 'wtr-Z~• 1 ~ I~._ : — • , •,• ~ - . ,. ?25,.12: ,:••1,••:.:::. •=..• 1 1 , • , • I 1 _ ,., ..._•• • •~ . .. • ~ ~ • . , ••• 506 ..~ +; • ~ Ib`s v`.~~;• ~/ . . I 141-41..~„ 5\:• . ~ • 1 , 5a0 • • ••A I~r. . C •• . i • ' .•.' ',. ~ ~ r~ ~:'" "• ~• • 1I . , O / I • ~ ~L'~ a ~ . .~- .~.~- .-.: -.. . .9a • • •• • I , ~' v, ~• • ~ ~ ~ • ~ i ~ ~1'• I A I • • • • POND ♦ • • I ; / w , •; 1, • 1 I • • I I ~ , • • ~ • , 0 . 1 • + • • , • • • • I. i 1• •• 1 I I /, • I • • t 1 • •

LEGEND 70% Nanr.0-144041TE '•~~•''~~~•~'~''~•~'~~'••''~''•~'~ DIP SECTION 30•70% NEMO•II.MEtsPa OF ANoRTW05117, LAC TIO ILMENITE DEPOSIT SCALE 1 6001

Percent of î"e203 in hero-iltaenite enncentrntes of reolc+ric.ù section

z O o O Ô 7 1.000 ..

... .-. ? .~ ~ ~ ~~ow, ~- ...men...... •7-9~-c, -.., IRM...... !r T-64-i 7-6"T-67.2~ -- T-71- O.» 44. e Ca T-75-2J T-79-5. •r .—• ~ '~ T-87-fo•I•:. :•r Valk/V'7.7L.4. ► { :..:•^ 261) , fla~pcn-r S ,~ , .-c.~~ 0.:;3:-.;:•::;: • Z Z~ ~ ~' ~ ~•p~~~~.~. ► r ► ~ ~ 30.5' d• ~:::•:•:;;'~~ 30: ~ ' .•...... •:r~~~c L :.`.' .'~•_~__'--M ~~•—_, " •~•,j~'!<; :.:.;... SOO ~~ ....::: ~ i. .44;44.;." :290 ► ~ ~ - I ~~ •~ ~ ~ •: •: : ..:•: . ï : : : s ~ - ~-♦~Lx " • : •:::.; ~ 30.â é;;~ =~~•e , % y4er ' ~ :ti•:•::•: i'~•~ ~ sr ►! , ..... /~ +, ~ I •~~•~,;~'•: ~•ïr • i a, 1 ~► / ►~ ~ ~•► ~► ~ + ~ \ ~ ♦ % ~ ~ ~ ~ ••• I '::i • 1 ••% r ~. I .. [y e, ~ ,r ``,: -.. • , f ~ S. ,,e -. erei///-/` ► ` - i _ ~ ► • ." , ~~ ,► ~ •_....: ,► , • . ; i , ► i . 1 r . / 1 -.. / ~ :~:~ :•::•: Ï :::'•: . ► 0 +.~"_ i • 1 r r ::Jwi ~~ ► i ♦ I ♦ ! ♦ ► l / ~ • ~ .I rÿ• ~_ •~ I ~ J ► \ ;— / ~ ' i r,I I / ► f ► ► .• ► .4. 0. -• I • ♦ 44 r .4.1 ► • I.• . 44. I* % I I -/ ♦ / r. ) /' . I' I ..,/ ► o•',/ •• I / .. / 1 ~ — • ,k, ..y00

LEGEND STRIKE SECTION ~:~... . 2> 70% H:iAO.ILMENi7E OF 3070% KEI.90-ILMEN{TE LAC i10 ILtVlENI d E DEPOSIT ,♦ ♦, ANORTNOSSTC âCALF 1"e 60O' LAKES

Percent of Fe203 in hemo-ilmenite concentrate, of gcolo;tical section •TK.

L t~t

~ ,._ _3 __ ..▪

.;< •• .• _ .. n~ ~ :"% ~ v. ♦ 7%97 / / / v . : .,.,; :C~* • ~7::• ~' : .~ ~ !.~ " r ~ ` Pre 1 ;r~T ' / ~ = ~c •••+..! ••• sm. T-Tj./, ,rr z Surface. /• ~ •~wL:_ iÎ 1-~ 7-33.5 T ‘ • / I l ♦ 1 ...♦ `-~%-9 + `~~ ~. ~ .• •.. ~ : ,S3 -9 ♦ ♦ ♦ - ,•,a ♦ ♦• ' ` ''`,. / ' , I ,':.~: T-;I?•5~~ ~ T-E'-s . • • / A t / `. ♦ ♦ •♦ \ 4 ' ~ :•••(':a ♦ % .•• ~ • / ♦ ♦ 1 / % /, / / / =•- ~ -) ~r /♦ • ♦ ♦• :♦ • ', ' $O0 1 % / \ i `. /• ♦ • • ~., • 4♦ 1 • / , . - . • ♦ - .\ / . 1 ••••.1.:. ...• 0 r ' ••♦•• •♦.. / / •. • ' .. 1 • \I~ • • ~ •~,~'~'~...'': ::: '•: ,' . • . •3 . • ♦ ~% ;'1 Î~♦ ';Ï ~.`: • • • Otl. 4 .. 0.18 t :~. • • ti • • . z / 1 • ti..`~' :'i.:^.. : J^, 1.7.Vi . ' % '•~, : .. • üüv • . `. \ 1 '. ♦ • • • ; ':: • • . • Z \ • ' \ I` • ~ •.•.: ~ ..d• . •": .r.~ •w %:•. f:•, t.. • S- ai ~\.^~ • ~ ~ ; % • I ;~~ r~ _.....^ „ • . •. O.it ~ ` ~ ~ ~ 1 . -_ ..:î.)• ' • . çnrkll!;r•; l• ,l~ i Y ••„ • / \/• ♦ .~•.; . ï • •• • ``^~ `•` MIA .I• / ...• jr.17 , t ,/• / ♦ I t 7• 4•.~~.~ ,`' ,` • ~• ••• ; :`;.`. ♦ % / . / / • ~ ' , / •~~ .• v~ •:: ,t ♦♦ ~~ 1 rÿi~i ~• • / /♦ ' - `, n.ÿ :/^~':~{:• :.1~~~~ '~: ,:w:ÿ ‘ ~~. ~' 1_/ •: i'^ 0•., , ~~ti~ v.• .` •. —/ . • \ a ; •• . • • /. • ~ ` ~ • • • •'• ''=K' . ' ti`Nj. 1 .f t • 1 / • I I •• '1'• ••\ `'4 :ï ~ • :• •''' •' •'• \ •• / / • 1 • i~ 1• • _/ . ±••` ~ww•~4•'a / ♦ I ♦ • ♦• / ~ / • ♦ •. •• •♦ t • .• 4 _ • I • 1 ♦ I 1 \ - • • ~ • / • 4 • • • ♦ •0 • 1 • / 7 • , , ~ I • • 1 4 • • • • • 1 • l 1, . 1 •• . ♦ t r I • ♦ 'e.-.•`•.•/

LEGEND. !O% kbNI -1:.W;_WRE ~ DIP SECTION 30,70% NE::30-iLr4dtutTC OF AltiOttTKOstri: LAC 110 1LMENITE DEPOSIT SCALE t"=6001

Y Y 1 Percent Al203 in hemo-ilmcllite concentrator of reoln ~•ical section I.,.

J ~

é ~ 2

✓ O o 0 o ta boo e ~~?

` "."4"..."~.% ,~ ...... m• .._ ~.. ~. r-,, ? ~ :1▪.. lb ✓ ~ "T.1.91."4 T-64-1 T-67-2 r 7=• 8 ~ _ 1~+;i. .~ .•~r ~~ ~ ~ ~ ...T-78-'Z 79-5 T-83-1 . ... .♦ `~ ~ 1. .r.. Dvl•S.CryT ►$at•On.-^i.-g_•-r .:.:~.... 8: 97-7t,~ .;. t ~..t.,-.. .i..-...,...... ,..,, ► O.IO~~: . • ,‘",„0.2~~p 2g e.21~;;=~ ...:,..-:-:•.•:•::•.•:-..:r.':'•:•:•••••'.~.: . ::::. •::: •ti, +'.` ..• -,- r. `~. ~'L ' . ~_ ,I • • .. ri •_ __.. _ _. , ~~~~.~^'~• Ÿ • • .' I0.-~ •~•::...••~.;- ..••~• ~. C00 ..i~...•'.•~.,'^•`~y~;•:Ï::•::::•:::;. • ç / 1 .. 1 r~ 1 ~,:i ~~~ 0.23 ~:; .::1:1:141 •- .• + _ . . .e e a _. . . . _. . . 0.3â.f'_'"~i L~i•: :~ ,~• •Z; . . M`= ♦ l t 1 ., 1‘ ...• :.... 4...d...... 1.;;; ~ / r ' t 'r .•1r 1 / ` / ..r; - 1 ~,` / ,I - 1\/~ ~ 1 r t ..1....% . t . 1 ~ ! , t . ~ . t t. ' / t r / ; • \1 1 '/ 0 .e ' 1 t ~ / •' :•::.:::: :: :::.~ ... • - 1 1 tl'•a I / ~~ :~: . ~ ti ' /. / , ~ :'~L:.„_ :._:--1- , i 1 s ♦ ~ r ♦ a 1~ ~ % ~ ' ~ -/ ~ t ' t 4 t ` _ ',. /~ j t / // 1 ~ 1.. I ` I t - / • ~ t- / ~ • 1 1 ~ r t - `' ~ . . .. • " t ~ ♦ / 1 ` -'~ 1 ♦ / r 1 I ~_ - / t r - . t - / .. I ~ 1 r • ♦ -500

S T P4.KE SE=C T IOM > 7o% 142140.1WtwVlTF O~ 7.0-70% r.arf,0-11.MEwIz& LAC ~i 6G tLMEN9 ô•L: DEPOSIT

ANORTKOSI T E SCALE t~• 6oe'

lAX~S

Percent A120 in riemo-il.mnnit:e concentrates of r:eolo~ical section .TK. 3

______~ ~~♦ r ~ res•..,-~ ~i•ô ~ ♦ • I r`;:, : . ..: . _ ~ Vh%I ♦/ • le.: ~ ? `. ~. ; r~•: : . ~ r; I ?~~ ~ .. ~ ? ...... ~ ~ ~ ~ •.. T797 .. ~ /'/• ♦/ ~;i: ~ - ~ = Î~•`;t?'• nee. 1 iL'i•~ïr•'••.• • ••• •. P4eS~•hZ Sv I r .L ~. ♦ ~ $7-4 ^~~~ C.• .,.•.._~ ~T.g35 • II 5 1 l , •; • i h ~ r • / / • •• T•83-3 / • ~ ♦! I• I \ 1 ~ ~• ,• a`ÿ. :::~:'... Q9 I_ I !i ri7 • I • • I ; I ••• • -'• ! o J i ♦ ~ l. ~ .~ . ~ .; •. . S0f) • I I ~"r • I ♦ I - •44: - -•• • I / • .• •M•r r I •r` ♦ I• "•••.?~ ! • - • I • 7‘,„~ • / • • • 1 - . .••~~,..•':': • • r - • ♦ - ~ • .. r~~•j,• T~~ ♦ '1 - \ • ~• • I•! 2t I '•~~5=. • ? • ~.~ t \ \ • • • • ,~ I' • ` ♦ i \II n`-•,:•.~n • ~• • • ...t.i ~/.,^. \ . ~ . •.{ ~.. .- :-•=~ •• c • ♦ • I• • • :i%•:::::: • y• `~,~ ~~• t I I ,r~4~J' i • f ~I r•' ',~1 7GVI • •::•• ~ i r ~•.°♦ ,....: . ...... -- • i • I • • - • ~ I • • t~~ ! .• -•:: ~.~t`I • . I• '•C:~: •• • 5% ~`•t t ~! i - • • f ~^••~!t••~" ~ ~ {: :~`i • •~-':~:~ • ~1 / - • i r .ID .Tr-r ~.Q ~, ~« ~ 1~• ~• i •: i • .I. •. r ~~ ~•~~~'•':~:::; :Vt~:~ 1N t I• • 1 I •: .~ ::•:'::•::•::iJ•~• ♦ ~r/ •\II v ~• ~ r i 1 s 1 ~ •• I - • ..60""b6., '4Ii4; I•I I. •- ••~ • i / / • •• I• • ~ i • • • 1 ~ •• -•- � • ~ - 1 i • -• ~ ~ • - Ir i' •• • r • I • 11. 1~ .I .. • • •• • I

LEGEND ~ 7o% 1+-m3at:-wITE DIP SECTION Jd-To% 14E.u0-iLc4ENrcE OF `• IoRT•tovrrE LAC TIC ILIIIIENITE DEPOSIT SCALE Ii1=40o°

Percent Cr2O1 in memo-'.Lmeni ;e concentrate of reolor ica1 section LM. 11111111MMEMENIIMINIBMEWRIONEM

!•S

o 0 o 7 Lboo

".N dome our, ona. alma WWII Ole 0.1. 01,0 OM. T-79-5 ••••• p 83.1 1741. (TPP:.P'ih S %.:74. "t T•• 67.4* . , • • ••••:e ••• „ • • 1 s -• • • / , • % ••• I I ,• , ...• • # ga. • ••• " / I • • • % % % 1 / / 1‘. " 1 ' / $ 0 lc 1 1 * I • • • • / a%/1% •• I t • -400

LEGEND • STRIKE: SECTIONI Effi > 70% HEMO.ILMENITE OF 30-70 % 1.150:0-ILMENITE LAC TIO ILMENITE DTEPOSiT

, • %, MontdoSITE scALE: Çaoo LAKES

Percent Cr 0 in hemo-ilmenite concentrates of 7eolcwica1 Lection JK. 2 1 CARTE GEOLOGIQUE DE LA REGION DU LAC ALLARD, COMTE DE SAGUENAY, QUEBEC (HARGRAVES, 19(32).

0 1 2 3 Km 1111 -3111111111---imm---J

0 1 2 MI. rauffinc--7111111Er

• • .

,52 •..1 8 •

Strike and dip of foliation Direction et pendage de la foliation '1AC PUYJALON

Strike and dip of contacts Direction et pendage des contacts

Inferred fault Faille supposée 94- ,- Railroad Voie ferrée / $7 — 60 ',•• -•.'s Cents:10s, known or inferred Contacts, connus ou supposés 7-Ire,..,4 I WJ• tZ- Anorthosite I:. Anorthosite Ir. ' , Oxide-rich norite Norite riche en oxide •••• O••./ ‘41-%•%-•;1.. - /rkt4••t`t tt,"(::'/srttf •••‘/.."-•-; \-V; -‘0‘ e•:1•••:•;"- „..1,1•1 •:„‘• %••• iN' ""' • Pyroxene syenite elneiss Gneiss sye'nitique à pyroxène '.1•••‘‘' ‘f••7'--‘1•/'4‘.../ ..1.•17'..7"si•.:1•••11". e • \%/"../ \**%, il -..‘"•'/'*) -" gmenite mussive • f••• !.-,"•.•)%'•- • iv•Vi s',700 C•• s' :r• "••% ''-v•i.11/-*,1-/is,‘,•."\--r.";••„;••1 Massive ilmenites 440 ••• • Ci> 1, - v;.•:- e ' ;;;••0'.\-7/":/-v e .• • 'g " 1•1.1.1••••••••••••••••=1. GEOLOGICAL MAP OF THE ALLARD LAKE AREA, SAGUENAY COUNTY, QUEBEC (HARGRAVES, 1962).

"1.