MINERALOGICAL MAGAZINE, SEPTEMBER I978, VOL. 4 2, PP. 385-9

Ferrierite" an Australian occurrence

B. M. ENGLAND AND J. OSTWALD The Broken Hill Proprietary Company Limited, Central Research Laboratories, Shortland, New South Wales, Australia

SUMMARY. An occurrence of the magnesian Barry Cole, discovered specimens of an unknown ferrierite at Unanderra, New South Wales, represents the in vesicles in latite while collecting in the first reported locality for this mineral in Australia. The then-working Wol|ongong City Council Quarry at ferrierite occurs in vesiclesin latite and is associated with Unanderra on the south coast of New South Wales. heulandite, laumontite, and calcite. Its crystal morpho- The crushed rock was being used for roadbase for logy is essentially similar to that of specimens from the type locality at Kamloops Lake in British Columbia. the Southern Freeway being constructed at that EPMA results are given for the Unanderra ferrierite and time and the quarry ceased operations on the its chemistry relative to other known occurrences is completion of that work. discussed. Unanderra ferrierite contains appreciably Subsequent X-ray powder diffraction analysis of more SrO2 than other ferrierites, but is significantlylower these samples carried out by the New South Wales in K20 and Na20. Mines Department at their Geological and Mining Museum in Sydney proved the mineral to be THE rare magnesian zeolite ferrierite was first ferrierite, the data agreeing with that published by described by Grahame (t9t8) following the Staples (I955). This locality at that time represented examination of specimens collected by Dr. W. F. the first occurrence of ferrierite in the southern Ferrier of the Canadian Geological Survey in a hemisphere and the fourth in the world. railway cutting on the north shore of Kamloops Geological setting of the ferrierite. The ferrierite Lake in British Columbia. At this locality the and associated are found filling large ferrierite occurs as spheroidal groups of bladed vesicles in the Dapto Latite Member of the Per- crystals up to 9 mm in diameter within a pale mian Shoulhaven Group, which outcrops between translucent chalcedony, which fills veins and Dapto and Unanderra, on the south coast of New vesicles in an olivine . South Wales. The section of latite exposed in the A calcium-rich ferrierite has been recorded from quarry is distinctly porphyritic in texture with well- the Eastern Rhodopes (Kirov and Filizova, I966) formed plagioclase (labradorite) crystals up to Io and an iron-rich variety from Alberto Bassi in the mm in length. It is partially overlain by sediments province of Vicenza, Italy (Alietti et al., I967 ). In of the Pheasant's Nest Formation (Bowman, I97o). recent years several ferrierite occurrences have The occurrence of Jerrierite and associated been recorded in the United States of America. minerals. The original specimens found showed These include: Agoura and Sonora Pass in Cali- spherulitic groups of closely packed blfided ferrier- fornia (Wise et al., I969); central Nevada (Regis, ite crystals deposited on transparent heutandite I97o); Altoona in western Wahkaikum County, crystals (fig. 1). Associated minerals were occa- Washington; and Silver Mountain, California sional prisms of aragonite up to Io mm in length, (Wise and Tschernich, I976). and crystallized calcite as both obtuse rhombo- Additional localities have also recently been hedrons and thin sheet-like crystals tabular on reported from British Columbia. Ferrierite is found {oooI}. These minerals were occasionally found near Monte Lake, 6 miles W. of Westwold in the associated directly with the ferrierite but more south-east Kamloops District; on the shores of commonly occurred separately in near-by vesicles. Pinaus Lake, 8 miles SE. of Westwold; and Fran- During July I97O, after the closure of the quarry, cois Lake, 3oo miles NW. of Kamloops Lake (Wise the locality was again visited by Mr. Cole and one and Tschernich, I976). Ferrierite has also been of the authors (B. M. E.). In the south face of the found in Japan (Yajima et al., I97I ) and from quarry a very large vesicle, almost completely filled Weitendorf, Styria, Austria (Zirkl, ~973). with very coarsely crystalline fawn and brown In August i966, a Sydney mineral collector, Mr. calcite with cleavage faces up to 3o cm across, was Copyright the Mineralogical Society 386 B.M. ENGLAND AND J. OSTWALD

FIGS. i 3: FIG. I (left). One of the original specimens of ferrierite collected from the Unanderra Quarry showing the compact spherical groups of bladed crystals on heulandite. Specimenis 5 cm diameter. FIG. 2 (centre). Spherical groups of bladed ferrierite crystals with well-formedtransparent heulandite. Specimenis 3 cm in length. FIG. 3 (right). Tabular calcite associated with radiating groups of ferrierite crystals. Specimen is 3 cm diameter. found. This calcite is strongly fluorescent in long- arranged in sub-parallel groups (fig. 3). These plates wave ultra-violet light, the fawn calcite showing are rarely more than o. I mm in thickness and are strong yellow and the brown showing patches of tabular on {oooI}, as shown by trigonal growth orange fluorescence revealing growth zoning not markings. Near-by vugs in the calcite body were otherwise visible in the specimens. Electron probe completely filled by this variety of calcite. mieroanalysis of these calcites showed only traces The minerals in the vug are deposited on a layer of Fe and Mg in the brown calcite and Mg in the of fine-grained intermixed calcite and chalcedony fawn calcite. No other elements were present at o'5 to 1"5 cm in thickness, which is separated from EPMA levels of detection. the coarse calcite by white and iron-stained crystal- The first mineral to be deposited in the vesicle lized laumontite (fig. 4)- was laumontite, as large well-formed prismatic The sequence of crystallization of the ferrier- crystals up to 5 cm in length penetrating into the ite and its associated minerals is summarized in coarse calcite. Patches of crystalline laumontite Table I. also occurred throughout the calcite body. This Crystal morphology of the ferrierite. Optical laumontite rapidly dehydrates to powdery leon- studies by Grahame (I 918) proved the mineral to be hardite, leaving moulds of the crystals in the calcite. orthorhombic. The Kamloops Lake crystals were Towards the centre of the calcite body a large vug was encountered which contained ferrierite, heulandite, and calcite. Here the ferrierite occurred as acicular bladed crystals arranged in spherical groups averaging 2- 5 mm in diameter deposited on well-formed transparent heulandite crystals (fig. 2). These groups were occasionally partly enclosed by the heulandite crystals. Each spherical aggregate of ferrierite crystals is composed of several groups of divergent blades with sub-parallel orientation, like the leaves of an open fan. This fan-like arrange- ment of the blades was also noted by Grahame (I918) in the Kamloops Lake material. Very small perfectly formed heulandite crystals were occasion- ally seen to be supported by groups of divergent FIG. 4- Part of the large cavity exposed, showing ferrierite ferrierite blades, the ferrierite often completely crystal groups with tabular calcite and heulandite crystals penetrating the crystal. deposited on a fine-grained aggregate of calcite/chalce- Deposited after the ferrierite heulandite are very dony, which is separated from the coarse calcite by white thin plate-like crystals of calcite up to 3 cm2 in area crystalline laumontite. Specimen is 7 cm in length. FERRIERITE FROM AUSTRALIA 387 TABLE I. Paragenetic sequence of minerals at Unanderra ferrierite and at first it was thought that Unanderra this may have been due to the ferrierite crystals lying with the a {IOO} face parallel to the carbon support film, in which case the dome d {xoI} faces I' rug I Laurnontite , I would not be observed. However, examination of Coarse calcite the crystals under an optical microscope showed ,, them to be terminated by the {oo i } face only. Fine calcite/chalcedony " I I The chemical composition of a number of indivi- Heulandite dual crystals of the ferrierite was obtained by Ferrierite -- ) electron probe microanalysis. Crystals broken from the groups were mounted on an epoxy resin Bladed calcite --I Aragonite surface. All crystals were checked by optical micro- scopy for the presence of extraneous minerals, and wall of centre of only monomineralic crystals were analysed. vesicle vesicle Analyses were carried out on an ARL-EMX unit at 15 keV accelerating voltage, o'o7 #A specimen current and a focused beam of about 2 #m diameter. Counting times were 2o seconds and the found to be tabular on { Ioo) with elongation along counting data were corrected by a programme the c-axis. Forms present were the pinacoids { I oo} devised by Wright (t973), based on the methods of and {oio} with the macrodome {IOI} terminating Duncumb and Reed (I968), Duncumb and Shields the crystals. A perfect cleavage parallel to {IOO} (I 966), and Reed (1965). All crystals examined were was also reported. of approximately similar thicknesses and all were Accurate measurements of refractive indices and analysed under similar conditions. 2V were not possible due to the small size of the As is well known, the analysis of presents individual crystals (less than o.ot mm in diameter) difficulties to the electron-probe microanalyst, but the optical properties o f the Unanderra ferrier- especially in relation to bound-water volatilization ite conform well with the data published by and in and potassium analyses. The heating Grahame (I918) and Staples (i955). effect of the electron beam causes the water to boil The crystal morphology of the Unanderra fer- off, causing the counting rates of the major elements rierite was further examined by transmission elec- to increase, as their effective concentration within tron microscopy. Some difficulty was experienced the excitation microvolume increases. The case in preparing samples for electron microscopy be- with sodium is more complex. In tectosilicates, cause of the tendency of the ferrierite crystals to sodium count rates have often been found to distort and intumesce under the heating effect of decrease with analysis time (Siivola, I969; Baird the electron beam in samples prepared by normal and Zenger, i966), but in alkali glasses an initial dispersion techniques. This was overcome by modi- decrease in sodium count rate is often followed by a fying the technique as follows: several crystal groups were selected under a binocular microscope and these were gently mixed with ethyl alcohol to form a slurry, which was dispersed on a glass microscope slide and allowed to dry. The surface of the slide supporting the crystals was then replicated using a two-stage plastic/carbon replica technique (Kay, I965). Samples prepared by this method showed greatly increased stability, the crystals being firmly locked in the carbon support film, enabling more accurate representation of crystal morphology in the photographs. Electron microscopy showed the major crystal forms of Unanderra ferrierite to be the two pina- coids a {loo} and b {oio}. A perfect cleavage parallel to {too} is present, conforming with the observations made by Grahame (I 918) (fig. 5). The present study also suggests the presence of a less FIG. 5. Transmission electron micrograph of the ferrierite perfect {ooi} cleavage. The dome form d {~oI} of crystals showing {Too} cleavage planes and the pinacoid Grahame's investigations was not seen on the {oIo} faces. Magnification • 700o. 388 B.M. ENGLAND AND J. OSTWALD large increase (Borom and Hanneman, I967). of the element (range o.63 -3"78 ~o) in the specimens Recently Butt and Vigers (i977) noted a rapid recorded by Wise and Tschernich (I976). To what increase in count rate for sodium during an EPMA extent alkali metal variations in zeolites are real or analysis of sepiolite and they attributed this to a instrument-induced is an open question. build-up of negative charge on the crystal surface. Acknowledgement. Appreciation is expressed to the As a result, sodium that are associated with the management of the Broken Hill Proprietary Company zeolitic water in internal lattice channels migrate Limited, Central Research Laboratories, for permission through this natural electrolyte to the electron to publish this work. beam position, thus causing a rapid anomalous increase in count rate. A similar effect has been REFERENCES observed by the authors in the EPMA analysis of levyne-offretite intergrowths. Here sodium counts Alietti (A.), Passaglia (E.), and Scaini (G.), I967. Am. increased twentyfold after an analysis time of only Mineral. 52, I562 3. IO min (Ostwald and England, in preparation). Baird (A. K.) and Zenger (D. H.), 1966. Adv. X-Ray Anal. The analyses (listed in Table II) must be con- 9, 487 . Borom (P. J.) and Hanneman (R. E.), 1967. J. App. Phys. sidered in the light of these difficulties. Though 38, 2406. measurements were made under similar instru- Bowman (H. N.), I97O. Rec. Geol. Surv. N.S.W. 12 (2), I63- mental conditions and on similar size grains, the 82. analytical totals vary considerably. This may well Butt (C. R. M.) and Vigers (R. B. W.), 1977. X-Ray be due to variation in thickness of the material Spectrometry, 6 (3), 144. analysed, i.e. variation in case of dehydration. Some Duncumb (P.) and Reed (S. J. B.), 1968. Nat. Bur. Stand. of the analyses (notably I, 4, 5, and 7) are within the (U.S.) Spec. Pub., 298. range of chemical variability of the mineral as and Shields (P. K.), 1966. The electron microprobe, described by Wise and Tschernich 0976). The Wiley, N.Y. Grahame (R. P. D.), i918. Trans. Roy. Soc. Canada (3), 12, variation in sodium and potassium is of interest, Sect. 4, I85 20I. with some crystals apparently being entirely free of Kay (D. H.), 1965 . Techniques for electron microscopy, 2nd alkali metals while others contain low to appreci- edn., Blackwell Sci. Pub., Oxford. able levels. The virtual absence of potassium in this Kirov (G. N.) and Filizova (L.), 1966. Ann. Univ. Sofia, material is in contrast with the consistent presence Fac. Geol. Geogr. 59, 237-46.

T A B L E I I. Chemical composition of Unanderra ferrierite

I 2 3 4 5 6 7 8 9 Average

SiO2 73"3 68'9 58"I 65"9 69"3 6I-2 71.5 60.6 69.1 66"4 A120 3 13.6 11-4 1i. 7 15. 5 i2- 7 14. 3 13.I II.8 a2.8 12.9 Fe203 nd* nd nd o.I 1.2 nd o-I nd nd o.i MgO 3"4 3"4 2"3 3"6 3"4 3"6 4"o 3"1 3"1 3"3 CaO i. 3 1.2 1-2 1.2 1. 3 1.7 I"3 i.i 1.2 I-3 SrO 1.1 1.o 0. 5 I.O 0-8 0"5 1.1 1.o 0.8 0"9 Na20 nd o. 7 nd 2"7 o-I I-8 0"7 o.I o.I o.6 K20 nd o. 1 nd o-2 nd o'3 nd o'3 o. I o. I H2OI" 7"3 I2"4 26.2 98 II3 I6-6 8. 3 22.0 I3.O --

Number of ions on the basis of 72 oxygens

Si 30"02 29"22 29"79 28-24 29-74 26"3I 29"73 29"76 3o"19 A1 6"49 5"63 6"98 774 6"34 775 6"32 6-8i 6.55 Fe -- 0.02 0.36 .... Mg 1.59 2.09 1.77 2.22 2.12 2.39 2"47 2.31 2-05 Ca o-41 o-51 o.61 o-51 0"56 083 0"54 0"58 0-58 Sr o-22 0.28 o.12 0.23 o.I 7 O.ll 0-22 o.26 o-17 Na -- 053 -- 227 r54 0-86 o-12 --

K -- -- 0-05 -- o-I4 0-34 o'15 -- Si + Al + Fe 36.51 34-85 36"77 36.0o 36"44 34"06 36"o5 36"57 36"74

* Not detected by EPMA. t By difference. FERRIERITE FROM AUSTRALIA 389

Regis (A. J.), i97o. Geol. Soc. Am. Abstr. Programs, 2, No. Wright (P. W.), 1973. Anal. Chem. 45 (1), IOI. 7, 661. Yajima (S.), Nakamura (T.), and Ishii (E.), I971. Mineral. Siivola (J.), I969. Bull. Geol. Soc. Finland, 41, 85. J. 6, 343 64. Staples (L. W.), I955. Am. Mineral. 40, Io95-9. Zirkl (J. V.), I973. N. Jb. Miner. Mh. 524-8. Wise (W. S.) and Tschernich (R. W.), I976. Ibid. 61, 6o-6. --Nokleberg (W. J.), and Kokinos (M.), I969. Ibid. 54, [Manuscript received 28 January I977, 887 95. revised 6 February I978 ]