Report on the Ore Mineralogy of Samples from the Lagoa Salgada, Volcanogenic Massive Sulfide (VMS) Deposit, Southern Portugal

Home , Chalcocite

Table of Contents

1. Samples and Methodology ...... 4

2. Textural Relationships ...... 6 2.1. Gossan ...... 6 2.2. Supergene zone ...... 9 2.3. Massive sulphides...... 10

3. Primary Microstructures ...... 12

4. Recrystallization Textures ...... 14

5. The Ore Mineral Suite ...... 18

6. Mineral chemistry ...... 23

7. Whole rock chemistry ...... 26

8. Attachments ...... 27

List of Figures Fig. 1 – Boxworks texture in gossan...... 7 Fig. 2 – Colloform texture...... 7 Fig. 3 - Hematite and goethite assemblages. Aspect of gossan...... 7 Fig. 4 – Gold particles in oxides...... 8 Fig. 5 - Ag-Hg amalgams and beudantite...... 8 Fig. 6 – Crystals of mimetite...... 8 Fig. 7 - Texture of samples in the supergene zone. Nic. //...... 9 Fig. 8 - Pyrite replaced by chalcocite. Nic. //...... 9 Fig. 9 - Pyrite framboids...... 10 Fig. 10 – Aggregates of collomorphic pyrite. Nic. //...... 10 Fig. 11 - Recrystallized arsenopyrite. Nic. //...... 11 Fig. 12- Sphalerite layer. Nic.//...... 11 Fig. 13 - Chalcopyrite and Tetrahedrite-Tennantite interstitial. Nic. //...... 11 Fig. 14 - Sample PX04A. Collomorphic textures of pyrite...... 13 Fig. 15 - Sample PX08-19. Layering of pyrite and sphalerite...... 13 Fig. 16 – Pyrite framboids...... 13 Fig. 17 – Annealing structure of pyrite...... 15 Fig. 18 - Sphalerite as inclusion in galena...... 15 Fig. 19 – Relationship with galena and sphalerite...... 16 Fig. 20 – Euhedral to subhedral crystals of pyrite and arsenopyrite...... 16 Fig. 21 – Chalcocite filling fractures in pyrite...... 17 Fig. 22 – Euhedral crystal and aggregates of pyrite...... 18 Fig. 23 – Inclusions of arsenopyrite in large crystal of pyrite...... 19 Fig. 24 – Crystals of arsenopyrite...... 19 Fig. 25 – Sphalerite with pyrite inclusions...... 20 Fig. 26 – Galena intergrowth with sulphosalt minerals and chalcopyrite...... 20 Fig. 27 - Tetrahedrite-tennantite intergrowth with sphalerite and pyrite...... 21 Fig. 28 - Chalcopyrite being replaced by chalcocite...... 21 Fig. 29 – Cassiterite in sphalerite...... 22 Fig. 30 – Gold particle in gossan...... 22

1. Samples and Methodology

The samples for ore microscopy were taken from four drill holes in the Lagoa Salgada deposit. These holes were chosen as they contained representative types of sulfide mineralization styles and mineral assemblages. Samples for the analysis were cores from different hole depths (metal zonation) classified into three characteristic groups: from gossan (weathering alteration), the transitional zone (with supergene enrichment), and the primary mineralization (massive sulphides).

Table 1 – Description of study samples.

Hole Number Samples FROM TO Stratigraphy PX01-01 Chert / jaspe 167.55 168.15 PX01-02 Chert / jaspe PX01 PX01-03 Chert / jaspe PX01-04 142.85 143.60 Gossan PX03-05 Gossan 145.00 145.80 PX03-06 Gossan PX03-07 Supergene PX03-08 Supergene 152.95 153.70 PX03-09 Supergene PX03 PX03-10 Supergene PX03-11 157.70 158.70 Supergene PX03-12 Massif sulphide 168.00 169.10 PX03-13 Massif sulphide PX03-14 168.00 169.10 Massif sulphide PX04A-15 173.75 174.30 Supergene PX04A PX04A-16 184.20 185.20 Massif sulphide PX04A-17 207.60 208.60 Massif sulphide PX08-18 150.80 151.80 Supergene PX08 PX08-19 165.85 166.70 Massif sulphide PX08-20 202.90 204.85 Stockwork

The techniques involved in the polished sections were carried out in the Porto University Science Faculty, DGAOT - FCUP laboratory. Ore microscopic studies were carried out in DGAOT – FCUP Laboratories using stereo-binocular microscopy and conventional reflected polarized microscopy. A conventional mineralogical examination was performed on the 20 samples to provide a detailed documentation of the ore mineralogy and document features that are of importance in mineral beneficiation studies.

A selected number of the polish sections were complementary examined using scanning electron microscopy and x-ray microanalysis (MEV-EDS) to confirm the identities of certain mineral ore; while others were selected to perform quantitative microanalysis at the electron microprobe.

2. Textural Relationships

The ore is particularly fine grained and is characterized by the development of fine- scale textures that show incipient to moderate degrees of recrystallization. The sulphide ores are therefore expected to show varying degrees of recrystallization in which the original primary microstructures may have been completely destroyed, but examples of less highly modified primary depositional textures may nevertheless survive locally. Relict primary microstructures are characterized by the presence of collomorphic and spheroidal primary precipitates as well as the widespread development of framboidal and polyframboidal textures. Recrystallization occurred to varying degrees and resulted in the development of a series of characteristic polycrystalline micro-structures as well as varying degrees of secondary grain growth that are most marked in essentially monomineralic or bimineralic areas of the ore, for example zones with euhedral crystals of arsenopyrite and / or crystals of pyrite.

Microscopic examination shows that the ore is sulphide-rich and consists predominantly of pyrite together with lesser amounts of sphalerite, galena and arsenopyrite as well as minor, but varying amounts of chalcopyrite and a variety of sulphosalt minerals. Fine grained quartz and rarer chlorite represent the dominant transparent gangue minerals. The microscopic observations indicate a metal zonation and three mineral assemblages can be distinguished: a gossan, a supergene alteration zone, and the massive sulphides. The gossan contains Fe oxy-hydroxide masses (hematite-goethite), and carbonates-silica assemblages, Ag-Hg amalgams, relict pyrite and small particles of gold. Additionally, in some samples, prismatic and aggregates of mimetite crystals are present. The zone of supergene alteration is characterized by fragmented pyrite, transformed to chalcocite with minor galena and sphalerite in a silicate matrix. Covellite and chalcocite are common, suggesting supergene alteration. The mineralogy of the primary mineralization consists of a wide variety of ore minerals, including pyrite (the dominant phase), sphalerite, arsenopyrite, tetrahedrite(-tennantite), galena, chalcopyrite, chalcocite, bornite, neodigenite, covellite and cassiterite.

2.1. Gossan The gossan from Lagoa Salgada consists mainly of goethite, hematite and silica with substantial amounts of gold and lead. In general, petrographic observations of the gossans confirm the predominance of goethite over the rest of the minerals and the main textures include: massive, boxwork, colloform and

open space fillings. The final result is a heterogeneous assemblage of residual fragments of early goethite, accompanied by quartz, hematite, and fragments of gossanized rocks cemented by late Fe-oxyhydroxides and siliceous particles. The precious metals mainly occur as Au–Ag– Hg and Ag–Hg amalgam particles. Gold usually occurs as very fine-grained particles. The high content in lead is explained by the presence of beudantite and mimetite crystals.

Fig. 1 – Boxworks texture in gossan.

Fig. 3 - Hematite and goethite assemblages. Aspect of gossan.

Fig. 2 – Colloform texture.

Fig. 4 – Gold particles in oxides.

Ag Hg S Qz Hg

Py Beu

Ox Fe

Fig. 5 - Ag-Hg amalgams and beudantite.

Mimetite Pb (AsO4) Cl 5 3

Fig. 6 – Crystals of mimetite.

2.2. Supergene zone

The supergene sulphide mineral assemblages are dominated by a small group of Cu-rich minerals: chalcocite, covellite and digenite. In the supergene blanket, these sulfides may be intergrowth with varying amounts of relict hypogene sulphides such as pyrite, galena and minor chalcopyrite and sphalerite. A homogeneous pyrite massif sulphide was brecchiated with the filling basically formed by pyrite fragments and chalcocite on a silicate matrix. Pyrite reacts to produce chalcocite and minor amount of galena. The aggregates of pyrite show radiated features.

Fig. 7 - Texture of samples in the supergene zone. Nic. //.

Fig. 8 - Pyrite replaced by chalcocite. Nic. //.

Fig. 9 - Pyrite framboids.

2.3. Massive sulphides The massive sulphide shows several degrees of recrystallization towards a more advanced stage with the development of monomineralic ore fragments of pyrite and also, on a much lesser extent, of sphalerite and galena, and minor tetrahedrite-tennantite, arsenopyrite, chalcopyrite. The massive sulphides exhibit primary textures as oolitic and radiated features. There are textural domains of pyrite massif sulphides and bands of continuous sphalerite and galena embedding recrystallized euhedral crystals of pyrite and arsenopyrite. Recrystallized euhedral crystals of pyrite (and arsenopyrite) have dimensions inside a large gap, between means values of 1 micron until 30 micron.

Fig. 10 – Aggregates of collomorphic pyrite. Nic. //.

Fig. 11 - Recrystallized arsenopyrite. Nic. //.

Fig. 12- Sphalerite layer. Nic.//.

Fig. 13 - Chalcopyrite and Tetrahedrite-Tennantite interstitial. Nic. //.

3. Primary Microstructures

The original structures results from a volcanogenic process, in relation with the massif sulphides were deposit in the form of extremely fine grained and often as colloidal sulphide precipitates. The primary precipitates subsequently recrystallized to varying degrees, as a consequence of diagenesis, alteration, very low grade metamorphism and deformation processes. The ores are formed by the accumulation of very fine and / or colloidal sulphides precipitates. Fine collomorphic and banded textures are preserved as relict structures. Other types of microstructures are very fined grained, spherical collomorphic (“oolithic”) and concentric banded bodies. The majority of these relict microstructures consists of extremely fine grained, spherical collomorphic and concentrically banded bodies, the maximum dimensions of which rarely exceed 25μm (Figure 14). These bodies may occur in isolation, but they are more commonly present in larger numbers and aggregates. A subordinate amount of the pyrite is also present in the form of various types of delicately banded, botryoidal and concretionary structures that have presumably developed by precipitation on larger, more continuous surfaces. The recrystallization of collomorphic layers result in the development of large numbers of small, elongated or acicular crystals that were orientated with its long axes normal to the layering. The various relict collomorphic bodies are most commonly preserved in areas where they are intergrowth with sphalerite and, to a lesser extent, with galena. These textures are particularly well preserved in areas of fragmental or rubble ore in which small, disjointed fragments of collomorphic pyrite are enclosed within a sphalerite-rich matrix (Figure 15). The collomorphic bodies are not commonly are nor commonly observed within the more massive pyrite-rich areas. A less representative proportion of relict structures consist of small discreet framboidal pyrite aggregates. A subordinate proportion of the relict microstructures consist of small discrete framboids and/or polyframboidal pyrite aggregates (Figure 16). These consist essentially of small rounded or spherical pyrite bodies that rarely exceed 25μm in diameter. The structure etching of many of the larger more massive areas of pyrite commonly shows the presence of patches or numbers of discrete framboidal bodies that are surrounded by areas of recrystallized pyrite aggregates.

Fig. 14 - Sample PX04A. Collomorphic textures of pyrite.

Fig. 15 - Sample PX08-19. Layering of pyrite and sphalerite.

Fig. 16 – Pyrite framboids.

4. Recrystallization Textures

The great bulk of the ore shows varying, but generally low degrees of recrystallization that reaches its maximum development within the monomineralic ore fragments that consist largely of pyrite, but also to a much lesser extent, of sphalerite and galena. The textural relationship that is observed on studied samples points to only a limited degrees of post- depositional recrystallization. The observed grain boundary relationship and textural features are explained in terms of depositional and subsequent geological processes that operate within the polymetallic sulphides Lagoa Salgada deposit. The relative proportions of individual ore do not be different significantly: the ore consist predominantly of pyrite with minor amounts of sphalerite, arsenopyrite, galena and tetrahedrite-tennantite. Both pyrite and arsenopyrite commonly exhibit euhedral crystals morphologies when are intergrowth with other facies, such us galena, sphalerite and tetrahedrite-tennantite. In contrast structure etching of the larger pyritic masses shows that they consist largely of fine grained, granular aggregates of pyrite that are present in the form of polygonal grains that exhibit straight to curved grain boundaries. These granular aggregates represent the recrystallization products of the former primary sulphide precipitates with their overall degree of recrystallization being reflected both by overall grain size (secondary grain growth) and the attainment of equilibrium grain boundary relationships.

1.1.1. Monomineralic Aggregates

Pyrite represents the dominant phase in the current ore and is present largely in the form of granular masses in which the component grains exhibit a wide range in grain size between an effective minimum of < lμm and a maximum that may exceed 150μm. Structure etching of the coarser pyrite grains and aggregates commonly shows that they are polycrystalline in nature and consist of large numbers of smaller crystals. The individual grains within these aggregates commonly exhibit a wide variation in grain size and often show the development of strongly curved grain boundaries. These features are indicative of recrystallization and the beginning of secondary grain growth processes, but the marked variations in both the morphologies and sizes of individual grains indicates that equilibrium was not generally attained. Similar relationships are evident. Within small essentially monomineralic pockets of galena and sphalerite. In the case of these two minerals the recrystallization often appears to have proceeded to a greater extent than that in the pyrite and the sphalerite grains commonly show the development of annealing twins which is further evidence for recrystallization.

Fig. 17 – Annealing structure of pyrite.

5.1.2. Polymineralic Aggregates

The presence of subordinate amounts of other phases (notably sphalerite and galena) within the pyrite-rich areas, however, seriously impeded the secondary grain growth processes in many areas of the ore that have remained relatively fine grained. There are areas where relationships of two mineral phases are well illustrated by sphalerite and galena. The small grains of sphalerite that are present within galena-rich aggregates will tend to exhibit relatively equant to rounded morphologies as follows in figure 18.

Fig. 18 - Sphalerite as inclusion in galena.

On the other hand, small grains of galena that are present within sphalerite-rich aggregates will tend to exhibit relatively elongated morphologies.

Fig. 19 – Relationship with galena and sphalerite.

In situations where pyrite and arsenopyrite are in contact with galena and sphalerite, these crystals tend to exhibit euhedral or subhedral crystal morphologies.

Fig. 20 – Euhedral to subhedral crystals of pyrite and arsenopyrite.

5.2. Fragmental and deformational textures

The studied polish surfaces allowed the identification of pyrite composite grains in which disjointed and angular fragments of collomorphic, and recrystallized pyrite, are present within a matrix of coarser grained sphalerite and finer detrital material. The fracture filling mineral assemblages also contains galena and sulphosalt mineral. The initial microscopic examination of the polished sections tends to show that a significant proportion of the pyrite is relatively massive and well-crystalline with euhedral crystal faces being developed locally. Microscopic examination of the various ore fragments also commonly indicates that a certain proportion of pyrite grains have been fractured to varying degrees. Normally only limited amounts of displacement of the individual fragments have occurred and the fractures are commonly filled with one or more of galena, sphalerite and sulphosalt minerals. The bulk of the small amount of chalcopyrite and associated copper sulphide phases in these ores is present as a component of these fracture-filling assemblages within the pyrite. This suggests, but does not prove that the chalcopyrite may represent a later-stage phase.

Fig. 21 – Chalcocite filling fractures in pyrite.

5. The Ore Mineral Suite

The current mineralogical examination was directed largely at the characterization of the more common ore minerals in preparation for metallurgical test work. The ore is extremely fine grained and it is highly probable that other ore minerals are also present in minor to trace amounts, but their characterisation was beyond the current scope of work. The individual ore fragments consist predominantly of sulphide minerals with transparent gangue minerals being present only in relatively small amounts. The individual ore fragments consist predominantly of sulphide minerals with pyrite being by far the most common phase. Both sphalerite and galena are present in subordinate amounts together with subordinate amounts of arsenopyrite and minor chalcopyrite. Other ore minerals including tetraedrite-tennantite and related sulphosalt minerals are present in very small amounts.

Pyrite Pyrite represents the dominant phase in the current ore and is present largely in the form of granular masses in which the component grains exhibit a wide range in grain size between an effective minimum of < l μm and a maximum that may exceed 150μm. The pyrite is also characterised by the development of a wide range of textures that range between relict primary collomorphic and framboidal microstructures through varying degrees of recrystallization to coarser grained, polygonal aggregates. The pyrite commonly represents the main phase in the majority of ore fragments with the result that sphalerite and galena as well as other less common ore minerals are generally present in the form of smaller grains that are located along the grain boundaries between larger pyrite grains. There is an intimate association of pyrite with arsenopyrite intergrowth with pyrite with pyrite patches within larger arsenopyrite grains, and arsenopyrite intergrowth as inclusions within larger pyrite grains. The pyrite grains and crystals also commonly contain tiny inclusions of the various associated ore and gangue minerals.

Fig. 22 – Euhedral crystal and aggregates of pyrite. 18

Fig. 23 – Inclusions of arsenopyrite in large crystal of pyrite.

Arsenopyrite The individual arsenopyrite crystals also exhibit a wide range in size between approximately 5μm and a maximum that exceeds 150μm. It is present largely in the form of discrete, elongated and rhomb-shaped crystals that are most commonly intergrowth with pyrite. These grains commonly exhibit crystal morphologies and may be present either as disseminated isolated phases or be present in greater numbers although discrete arsenopyrite- rich aggregates are rare. Both isolated arsenopyrite crystals and larger numbers of these grains are also commonly intergrowth with the other ore minerals in the samples including galena, sphalerite and various sulphosalt minerals.

Fig. 24 – Crystals of arsenopyrite.

Sphalerite The larger sphalerite grains (typically > 20μm in size) commonly show the presence of small numbers of tiny chalcopyrite and, to a much lesser, galena and pyrite inclusions. The pyrite and galena inclusions are generally < 5μm in size, but the chalcopyrite inclusions are typically < 2μm in size. Relatively small amounts of sphalerite are present in the form of tiny sub-micrometre-to micrometre-sized particles that are intergrowth with relict collomorphic pyrite.

Sphalerite is commonly present in subordinate amounts to pyrite and is therefore often present as a moderately abundant, but nevertheless widely disseminated phase within pyrite-rich ore fragments. Structure etching commonly shows that the apparently larger sphalerite grains may consist of aggregates of finer polygonal grains, many of which show the development of characteristic annealing twins. The sphalerite is characterised by the presence of light reddish- brown coloured internal reflections that is usually indicative of the presence of a certain amount of Fe in solid solution.

Fig. 25 – Sphalerite with pyrite inclusions.

Galena The grain size of galena is therefore also highly variable and ranges between a minimum of < 1 μm and a maximum of 150μm. The bulk of the galena is, however, most probably present in the form of grains that are less than 25μm in size. The nature and mode of occurrence of the galena is essentially the same as that of sphalerite and it exhibits an equally wide range in grain size and degree of intergrowth with pyrite, arsenopyrite, sphalerite and other ore minerals. The galena is commonly intergrowth with varying amounts of sulphosalt minerals and, to a lesser extent, chalcopyrite.

Fig. 26 – Galena intergrowth with sulphosalt minerals and chalcopyrite.

Tetraedrite-tennantite and Related Sulphosalt Minerals

Tetrahedrite-tennantite is typically present in the intergranular areas between larger pyrite grains where they may be intergrowth with one or more of sphalerite, galena, arsenopyrite and/or chalcopyrite. This mineral appear in a different range of sizes.

Fig. 27 - Tetrahedrite-tennantite intergrowth with sphalerite and pyrite.

Chalcopyrite and Other Copper Sulphides The chalcopyrite grains rarely exceed 50μm in size and are commonly smaller. They also tend to occur in association with galena and/or various sulphosalt minerals. The bulk of the chalcopyrite is present in the form of discrete small grains that are either developed along grain boundaries between larger pyrite grains or are present as components of fracture-filling assemblages. The bu1k of the chalcopyrite appears fresh and unaltered, but subordinate proportions of the grains are intergrowth with and partially replaced by an anomalous blue Cu-sulphide phase. This phase is strongly anisotropic and resembles covellite, but lacks the characteristic red-violet interference colours when viewed between crossed polars. In this study this mineral phase was characterized by chalcocite. The bornite is most commonly developed in the form of narrow rims around chalcopyrite grains and may also be developed along fractures and cleavage planes. This feature strongly suggests that it exhibits a replacement relationship towards chalcopyrite, which suggests supergene alteration.

Fig. 28 - Chalcopyrite being replaced by chalcocite.

Cassiterite Cassiterite appear as inclusions and fine intergrowths with sphalerite, with a maximum size of 5µm. Careful examination of the larger sphalerite grains, however, commonly shows the presence of numbers of small, discrete cassiterite crystals that sparingly distributed throughout their hosts.

Fig. 29 – Cassiterite in sphalerite.

Gold After a carefully microscopic examination was possible identify some gold particles in the gossan and some of them were confirmed in the electron microprobe.

Fig. 30 – Gold particle in gossan.

6. Mineral chemistry

The mineral geochemical analyses were performed on a fully automated JEOL JXA- 8500F microprobe running at the LNEG Laboratory. It was analyzed the following mineral phases: Pyrite (Py) Arsenopyrite (Apy) Sphalerite (Sp) Tetrahedrite – Tennantite (Tn – Tt) Galena (Gn) Chalcopyrite (Ccp) Chalcocite (Cc) Covellite (Co) Complex sulphides of Fe, Pb, Cu Complex sulphides and sulfosals of Ag and Hg

The mineral compositions of primary phases (earlier and recrystallized generations) are presented on table 2.

Table 2 – Mineral compositions of primary phases.

Py Apy Sp Ccp Gn Inclus. Band Primary Recristall Primary Recristall Second. Interstit. Interstit. Apy interstit. Nº 5 6 1 7 2 9 2 3 5

Ag 0.021 0.002 0.002 0.014 - - - - - Se 0.05 0.06 0.07 0.08 0.03 0.07 0.05 0.07 0.07 S 52.01 51.40 21.75 22.96 32.25 32.78 30.46 34.26 14.42 In 0.03 0.01 - 0.01 2.30 0.07 0.01 0.03 - Fe 46.59 45.69 35.66 34.10 3.62 3.69 0.64 30.03 1.96 Bi 0.15 0.20 0.00 0.07 0.10 0.14 0.10 0.07 0.35 Te 0.03 - - 0.02 0.02 0.01 0.02 0.01 0.06 Ge 0.02 0.04 0.00 ------Sn 0.03 0.01 - 0.02 0.03 0.02 - 0.02 0.01 Cd 0.01 0.01 0.01 0.02 0.25 0.18 2.33 0.01 0.01 Cu 0.80 0.08 0.05 0.08 1.41 0.25 2.12 34.45 0.22 Pb 0.14 0.14 0.05 2.96 0.03 0.28 0.17 0.12 83.35 Zn 0.02 0.17 0.02 0.82 56.07 61.76 62.01 0.20 0.39 As 0.43 0.38 42.36 38.62 2.06 0.13 0.15 0.20 0.10 Sb 0.04 0.07 0.03 0.53 - 0.02 - - 0.07 Au ------Hg ------

Primary Py records Ag (188 – 226 ppm) and minor amounts of Cu (1.6 – 1.9%) into its mineral structure. Recrystallized Apy shows some amounts of several metals into its structure: Au, 65 ppm; Ag, 254; Zn 4.7%. It was analysed two main generations of Sp. The generation occurring as inclusion inside recristallized Apy has about 2.3% In and 1.4% Cu, while the generation of Sp occurring as bands – the most important on all samples – interlayered with Py, has a mean value of 0.07% In and 1% Cu. One exemplar records 9 ppm Au. Sp secondary records about 2% Cd and 3.52% Cu. On Ccp that occurs as an interstitial phase on Py, it was detected amounts of Ag between 25 and 104 ppm. The generation of Gn was the latest to crystallizing as an interstitial phase. It was detected 1% Zn, 0.8% Cu and 197 ppm Au. The composition of secondary phases (later ones and/or supergenic generations) are presented on Table 3:

Table 3 – Composition of secondary phases.

(Fe, Pb, Cu)S2 (Fe, Pb)2S3 Ag_Hg Cc Bn

Second. Second. Second.

Nº 2 2 3 4 3 Ag - 0.0458 - - 0.087 0.028 0.111 Se 0.15 0.01 0.0596 0.150 - 0.085 0.095 S 48.20 38.29 26.72 19.21 26.39 22.0 31.1 In 0.00 - - - 0.01 0.012 - Fe 41.98 30.76 18.03 11.25 1.34 0.858 14.88 Bi 0.20 0.09 0.11 0.05 0.10 0.097 0.129 Te - - - 0.01 - - - Ge - 0.01 - - 0.02 0.02 0.003 Sn - 0.01 - 0.00 - 0.063 - Cd - 0.02 - - 0.78 0.017 0.018 Cu 2.57 15.20 1.31 0.47 39.17 76.3 51.94 Pb 7.19 12.87 45.75 55.58 2.69 0.063 0.328 Zn 0.02 0.06 - 0.01 4.86 0.249 0.078 As - - - 15.06 0.127 0.066

Sb 0.04 0.07 0.05 1.06 0.002 0.013

Au ------

Hg - - 8.19 0.033 -

The primary pyrite phases were transformed into secondary phases, identified as two main groups: one group has a replacement of Fe to Pb and Cu, with a stechiometric relationship

about (Fe, Pb, Cu): S2; the other group has a replacement of Fe to Pb, with a stechiometric relationship about (Fe, Pb)2: S3. These are the most representative transformations of Py. Small amounts of complex sulphosals of Ag-Hg records Ag (700 to 1000 ppm), Hg (about 10%), Cu (38-42%), Pb (about 3%), Zn (about 5%) and Sb (~3%). It were identified secondary copper sulphurs like Cc e Bn, this last one phase with small amount of Ag (150 – 420 ppm).

7. Whole rock chemistry Metals analysed on samples submitted to petrographic study are summarized on next table, together with the mineralogy observed on microscope. Explanation

MINERALOGIC EXPLANATION FOR METALS HOLE SAMPLE FROM TO STRATIGRAPHY Au Ag Cu Pb Zn GRADE ppm ppm % % %

01 Chert / jaspe 4.49 8 0.005 0.476 0.063 Native gold not observed on sample 02 167.55 168.15 Chert / jaspe 4.49 8 0.005 0.476 0.063 px01_03 px01 03 Chert / jaspe 4.49 8 0.005 0.476 0.063

04 142.85 143.60 Gossan 0.26 11 0.093 3.61 0.663 Minerals phases with Pb not observed

05 145.00 145.80 Gossan 6.93 67 0.071 12.3 0.48 (not studied)

06 145.80 146.80 Gossan 3.22 439 0.132 12.3 0.174 (not studied)

07 192 4.46 20.78 0.047 Au and Ag: Native gold or electrum not 08 192 4.46 20.78 0.047 observed; Pb: Galena and mineral phase 152.95 153.70 Supergene 1.73 with Pb, O and S; Cu: Tetrahedrite- 09 192 4.46 20.78 0.047 tennantite and rare chalcopirite

px03 10 192 4.46 20.78 0.047 Au and Ag: Native gold or electrum not 11 157.70 158.70 Supergene 1.67 178 0.432 10.55 0.346 observed; Pb: Galena and mineral phase with Pb, O and S Au and Ag: Native gold or electrum not 12 Massif sulphide 1.8 145 3.31 9.36 2.05 observed; Pb: Galena and mineral phase 168.00 169.10 with Pb, O and S; Cu: Tetrahedrite- 13 Massif sulphide 1.8 145 3.31 9.36 2.05 tennantite and rare chalcopirite and sulsecCu; Zn: Spharelite Au and Ag: Native gold or electrum not 14 216.70 217.80 Massif sulphide 3.48 134 0.197 8.99 9.08 observed; Zn: Sparelite; Pb: Galena and mineral phase with Pb, O and S Au and Ag: Native gold or electrum not 15 173.75 174.30 Supergene 3.02 107 0.267 10.25 4.06 observed; Pb: Galena; Zn: Spharelite Au and Ag: Native gold or electrum not px04A 16 184.20 185.20 Massif sulphide 1.33 60 0.2 8.46 11.5 observed; Zn: Spharelite; Pb: Galena Amount of spharelite and galena not 17 207.60 208.60 Massif sulphide 0.39 39 0.307 1.83 1.81 compativel with low grade on Pb and Zn Au and Ag: Native gold or electrum not observed; Cu: Tetrahedrite-tennantite and 18 150.80 151.80 Supergene 1.31 92 6.14 3.32 0.074 rare chalcopyrite and sulsecCu; Pb: The amount of Galena does nor explain the px08 grade Au and Ag: Native gold or electrum not 19 165.85 166.70 Massif sulphide 1.27 138 0.498 10.3 5.42 observed; Pb: Galena; Zn: Sparelite Cu: Chalcopyrite and tetrahedrite- 20 202.90 204.85 Stocwork 0.07 28 2.34 0.089 2.34 tennantite; Zn: Spharelite

8. Attachments

Indium and Selenium occurrence on Lagoa Salgada Ores

The increasing consumption of indium (In) and selenium (Se) has significantly stimulated their extraction output, adding economic interest to critical metal sources that a few years ago were either unknown, or unconsidered (Pinto et al., 2014). The Iberian Pyrite Belt is one of the most outstanding European ore province, hosting one of the largest concentrations of massive sulphides in the Earth’s Crust. Lagoa Salgada orebody, the most northerly of the Iberian Pyrite Belt known so far, is a massive sulphide deposit with an inferred mineral resource of 3.7 Mt. The orebody has been described as composed of a central stockwork zone – a thick Volcano Sedimentary Complex with more than 700m – and a massive sulphide lens in the northwest. It is covered by more than one hundred meters beneath sediments of the Sado Tertiary basin (Lima et al., 2013). The ore mineralization assemblage is mainly composed of pyrite with minor sphalerite, chalcopyrite, galena, tetrahedrite-tennantite, arsenopyrite, stannite, cassiterite, and supergene minerals which are in different amounts represented throughout the basic textural domains. In Lima et al. (2013) were studied polished sections of massive sulphide ore samples by Electron-probe microanalyses (EMPA). It was identified one generation of sphalerite, with mean granular dimension of 20 µm included on recrystallized arsenopyrite, that has 23000 ppm of In. This value is three times more In content than the best value found on other studied sphalerite examples on the same orebody deposit (Oliveira et al., 2011). This discovery leads the exploration concession holder Redcorp to put more efforts to find more detail information in high-tech metals in the Lagoa Salgada Deposit as possible by- products of copper-lead-zinc ores. Recently new samples were collected to test the presence of Se and In on other areas not studied before as the so-called Central Stockwork (Borehole LS28 and LS26). One sample of breccia with 1,5-meter thickness (LS28_2) with Cu (1,01%), Pb (4,46%) and Zn (5,23%) has 194 ppm of Se. The average of 3 samples with 4 m on this borehole LS28 is 99 ppm, and the nearby borehole LS26 has 3 m sequence with 101 ppm in average. Already in Oliveira et al (2011) Se was analyzed in other part of the orebody with results as high as 146 ppm Se in the borehole LS5. The metallographic study is being developed and no junoite was found until the moment, but the strong association with Pb and Zn is related to the presence of Se on galena and rarely with sphalerite as in Neves-Corvo (Pinto et al. 2014). Again the complexity of this deposit highlights the need of prospecting new areas inside the orebody with predominance to the already 2 identified high-tech metals that possibly can be important by-products. Ongoing works on the Lagoa Salgada (re-logging, ore microscopy and whole rock geochemistry, etc) would define the feasibility of the principal ores as Cu-Zn-Pb but also by-products as Au, Ag, and now In, Se.

Study Results

Indium highlights

The main new result of this study was the identification for the first time in Lagoa Salgada Deposit of half micron discrete crystals of In mineral in chalcopyrite, associated with cassiterite, and on the contact with sphalerite all them as inclusions of euedric arsenopyrite crystal (Fig. 1,2 and 3). Eighteen discrete In minerals are known, and these are found only in very In-rich systems. The most important is roquesite, CuInS2 which is isostructural with chalcopyrite, CuFeS2. Other minerals include dzhalindite In(OH)3; indite FeIn2S4; native In; petrukite (Cu, Fe, Zn, Ag)3(Sn, In)S4; and sakuraiite (Cu,Zn,Fe)3(In,Sn)S4 (Andersen et al. 2016).

Fig. 1- Arsenopyrite crystal with inclusions of In rich sphalerite (23000 ppm) and chalcopyrite where we can find discrete particles of In mineral (white square, Fig. 2 and 3).

Fig. 2 - Zoom of Fig. 1 centred on chalcopyrite and sphalerite inclusions of arsenopyrite.

Fig. 3 - Chalcopyrite where can be seen the areas of cassiterite associated with In mineral, close with the contact of sphalerite.

Fig. 4- Distribution of different elements on the sphalerite/chalcopyrite inclusion in idiomorphic arsenopyrite.

Against what was toughed before, the In rich sphalerite can be included not only in Arsenopyrite, but also in Pyrite (8,9,10, see table 1) and other minerals. The control of richness in Indium seems to be related with presence of tiny Cu and Sn minerals in the neighbour. The maximum results on sphalerite reached 31360 ppm on EMPA (average of 21626 ppm of 11 measures, see table 1), and is very rare elsewhere on the world. Selenium is present on some sphalerites reaching 550ppm and with average of 135ppm. Also the chalcopyrite has more than 2000 ppm In but no Se on the 2 assays done (Fig. 4). Even the Arsenopyrite has 400 ppm In average, and only pyrite is completely sterile in Indium.

Table 1 – Results of EMPA on sphalerites of sample PX-08-20A (Fig. 5)

Sample 1 2 3 4 5 6 7 8 9 10 11 Average Comment Bi 0 0 0 0 0 0 0 0 0 0 0,003 0,0003 Ga 0 0 0 0 0 0 0 0 0 0 0 0 Pb 0,022 0 0 0,074 0,102 0 0,007 0 0,059 0 0,121 0,035 Au 0 0 0 0,002 0 0,048 0 0 0 0,05 0 0,0089 Ag 0,009 0,028 0,024 0 0,02 0 0,01 0 0 0,01 0 0,0095 Ge 0,002 0,019 0 0,011 0 0,001 0 0 0 0 0 0,003 Cd 0,239 0,288 0,15 0,296 0,319 0,268 0,262 0,146 0,294 0,3 0,138 0,2454 Mo 0,073 0,063 0,044 0,076 0,128 0,066 0,097 0,117 0,108 0,09 0,081 0,086 In 2,239 2,383 1,563 2,083 2,467 1,888 1,955 2,232 2,967 3,12 0,896 2,1626 As 0 0,011 8,156 0,055 0,002 5,7 0,131 0,042 0 0 0,019 1,2833 Sn 0 0 0 0 0 0 0 0 0 0 0 0 S 32,88 32,889 30,45 33,11 32,89 31,333 34,5 33,02 32,55 32,7 32,65 32,632 Ni 0,017 0 0 0,035 0,019 0,03 0 0 0,008 0 0,043 0,0138 Se 0 0 0 0 0 0 0,054 0,055 0,009 0,03 0,001 0,0135 Zn 59,39 59,827 47,09 58,97 59,52 53,823 55,09 60,16 58,57 58,1 62,87 57,582 Fe 3,696 3,759 10,67 3,264 2,876 6,568 7,192 3,388 3,596 3,45 2,292 4,6133 Sb 0 0 0 0 0 0 0 0 0 0 0 0 Mn 0 0 0 0,011 0 0,018 0 0 0 0,04 0,004 0,0065 Co 0,01 0,028 0 0,033 0,01 0,062 0 0,011 0,018 0,01 0,019 0,0178 Cu 1,281 1,318 0,973 1,513 1,634 1,229 1,072 1,48 1,678 1,75 0,568 1,3182 Total 99,86 100,61 99,11 99,53 99,98 101,03 100,4 100,6 99,85 99,6 99,71 100,03

The sphalerite of PX-08-20b (table 2) just on the stockwork below the massive sulphide of PX- 08-20a is less rich with average of 350 ppm In (with a maximum of 930ppm). By the portable XRF analysis we can see that PX-08-20b sample is much more poor in Cu (0,4%) and Zn (0,6%) than the massive sulphide (6,6% Cu and 7,3% Zn) (see Fig. 6). Anyway, the problem is that we do not have whole rock geochemistry for In, Se and other elements of this part of the deposit that was crossed by the borehole PX-08.

4 Apy

Apy Py 11

1 2 1 Apy 2 7 6 3 Apy

10 9

Fig. 5- EMPA Analysis of sphalerite in white numbers (see table 1 for results) and black numbers the two analysis in chalcopyrite.

Table 2 – Results of EMPA on sphalerites of sample PX-08-20B (Fig. 6)

Sample 1 2 3 4 5 Average Comment Bi 0 0 0 0,029 0,042 0,0142 Ga 0 0 0 0 0 0 Pb 0,108 0 0,292 0,083 0,161 0,1288 Au 0 0,009 0 0 0,023 0,0064 Ag 0 0 0 0 0,011 0,0022 Ge 0 0 0 0 0 0 Cd 0,229 0,241 0,115 0,747 1,021 0,4706 Mo 0,087 0,079 0,059 0,056 0,127 0,0816 In 0,072 0,093 0 0 0,033 0,0396 As 0,028 0 0,025 0,333 0,088 0,0948 Sn 0 0,012 0,061 0,011 0,034 0,0236 S 33,179 33,241 33,639 32,879 32,829 33,1534 Ni 0,005 0,02 0 0,034 0,023 0,0164 Se 0,02 0,043 0,001 0 0 0,0128 Zn 64,162 63,845 48,965 63,188 62,562 60,5444 Fe 2,562 2,448 8,494 1,017 1,263 3,1568 Sb 0,002 0,053 0,008 0 0 0,0126 Mn 0 0,044 0 0 0,016 0,012 Co 0,017 0 0,034 0,023 0 0,0148 Cu 0,222 0,559 10,98 3,059 1,898 3,3436 Total 100,693 100,687 102,673 101,459 100,131 101,1286

Fig. 6 –Sample PX-08-20B with some sphalerite in lighter grey where was done the assays of table 2.

Selenium highlights

The main new result of this study was the identification for the first time of galena rich on Selenium, with 4904 ppm in average on sample LS-28-27 (Table 3). The galena has a silver content that is not negligible (1310ppm average).

Table 3 – Results of EMPA on galenas of sample LS-28-27 (Fig. 7)

Sample 1 2 3 4 5 Average Comment Bi 0 0 0 0 0 0 Ga 0,041 0,022 0,023 0 0 0,0172 Pb 86,021 85,592 83,969 86,893 86,604 85,8158 Au 0 0 0 0 0 0 Ag 0,106 0,091 0,128 0,201 0,129 0,131 Ge 0,017 0,033 0,033 0 0,022 0,021 Cd 0 0 0 0 0 0 Mo 0 0 0 0 0 0 In 0 0 0,017 0 0 0,0034 As 0 0 0 0,006 0 0,0012 Sn 0,017 0,047 0,041 0 0 0,021 S 12,937 12,898 12,864 12,806 12,706 12,8422 Ni 0 0,093 0,042 0 0 0,027 Se 0,538 0,496 0,486 0,396 0,536 0,4904 Zn 0,107 0,012 0 0,275 0 0,0788 Fe 0,226 0,189 0,19 0,246 0,293 0,2288 Sb 0 0 0,019 0 0 0,0038 Mn 0 0 0 0 0 0 Co 0,022 0 0,003 0 0,019 0,0088 Cu 0,052 0,138 0 0,362 0,37 0,1844 Total 100,084 99,611 97,815 101,185 100,679 99,8748

3 4 5

Fig. 7 - Pyrite crystal with surrounding chalcopyrite and galenas of sample LS-28-27 analysed on table 3.

Bibliography

Andersen J., Stickland R. J., Rollinson G. K, Shail R. K. (2016) Indium mineralisation in SW England: Host parageneses and mineralogical relations. Ore Geology Reviews. http://dx.doi.org/10.1016/j.oregeorev.2016.02.019

Lima A. M. C., Rodrigues B.C., Oliveira A. & Guimarães F. (2013). Recent Research on Indium from The Lagoa Salgada Orebody, Iberian Pyrite Belt, Portugal. Mineralogical Magazine, July 2013, v. 77, p. 1610.

Oliveira D. P., Matos J. X., Rosa D. R. N., Rosa C. J. P., Figueiredo M. O., Silva T. P., Guimarães F., Carvalho J., Pinto A., Relvas J. and Reiser F. (2011) The Lagoa Salgada Orebody, Iberian Pyrite Belt, Portugal. Economic Geology 106 1111- 1128

Pinto A. M. M., Relvas J. M. R. S., Carvalho J. R. S., Liu Y., Pacheco N., Pinto F., and Fonseca R. (2014) High-Tech Metals in the zinc-rich massive ores of the Neves Corvo Deposit. Comunicações Geológicas 101, Especial II, 825-828

Ore microscopy

PX01-01 Sample:

Gold occurs in grain boundaries. Nic. //. Silica matrix with relict of hematite. Nic. //.

Material: Chert/jasper facies

Composition: Fractured and oxidized (hematitic and goethitic oxidation) previous sulphide mineralization.

Assemblages of hematite and goethite. Nic. //. Assemblages of hematite and goethite. Nic. +. Minerology:

Goethite Hematite Silica Gold

Ore microscopy

PX01-02 Sample:

Hematitic/goethitic material. Nic. +. Hematitic/goethitic material. Nic. //.

Material: Chert/jasper facies

Composition: Fractured and oxidized (hematitic and goethitic oxidation) of previous sulphide mineralization. Breccia Colloformic texture of goethite. Nic.//. Colloformic texture of goethite. Nic.+.

Minerology:

Goethite Hematite Silica Gold

Ore microscopy

Gold on iron oxide. Nic. //.

Ore microscopy

Sample: PX01-03 Chert. Nic.//. Chert. Nic.+.

Material: Chert/jasper facies

Composition: Siliceous banded structure

Minerology:

Silica

Ore microscopy

Sample: PX01-04 Goethite. Nic. //. Inclusions of pyrite. Nic. //.

Material: Gossan

Composition: Gossanized "massive sulphides"

Minerology:

Colloformic goethite Hematite Oxidized banded structure. Nic. +. Silica Inclusions of pyrite in quartz

Ore microscopy

Sample: PX03-05 Gold particle in oxides. Nic. //. Colloformic textures of goethite. Nic. //.

Material: Gossan

Gossanized "massive sulphides" Composition:

Minerology:

Goethite with collomorphic textures

Hematite Inclusions of pyrite. Electron microprobe image. Gold particles. Quartz

Pyrite as inclusions Beudantite Gold Ag-Hg amalgams

Ore microscopy

Electron microprobe image.

Ag Hg S qz Hg py

beu

Ox Fe Ag-Hg amalgams Beu - Beudantite

Ore microscopy

Sample: PX03-06 Crystals of mimetite. N//. Crystals of mimetite. N+.

Material: Gossan

Composition: Gossanized "massive sulphides"

Minerology:

Goethite Crystals of mimetite. N//. Crystals of mimetite. N+. Hematite Mimetite in euhedral crystal, aggregates and in a small veins

Ore microscopy

Mimetite in open spaces and filling a small vein.

Ore microscopy

Sample: PX03-07 Texture of sample. Nic. //. Pyrite replaced by chalcocite. Nic. //.

Material: Supergene zone

Composition: The pyrite massif sulphide is intensely fractured and transformed to a mineral phase with Cu and S, maybe chalcocite. Less important fractures are filled by euhedral pyrite on a silicate matrix. Pyrite framboids. Interstitial covellite. Minerology:

Pyrite Chalcocite

Silica Covellite Cassiterite Amalgams of Hg-Ag

Ore microscopy

Cassiterite. Electron microprobe image.

Ore microscopy

Sample: PX03-08 Collomorphic pyrite. Nic. //. Sphalerite layer. Nic.//.

Material: Supergene zone

Composition: sample is interlayered with bands of interstitial sphalerite, sometimes in euhedral grains, with greater or lesser amount of galena, embedding euhedral crystals of recrystallized pyrite and arsenopyrite. Recrystallized arsenopyrite. Nic. //. Chalcopyrite and Tetrahedrite-Tennantite interstitial. Nic. //. Minerology:

Pyrite in layers and euhedral crystals Sphalerite Galena interstitial or filling fractures Arsenopyrite in euhedral crystals Tetrahedrite-Tennantite Chalcopyrite interstitial or filling fractures Quartz Cassiterite as inclusions and fine intergrowths with sphalerite

Ore microscopy

Galena (light grey), Tetrahedrite-Tennantite (green) and Cassiterite as inclusion in sphalerite. Electron sphalerite (dark grey). Nic. //. microprobe image.

Ore microscopy

Sample: PX03-09 Relict of pyrite. Nic. //. Fracture with hematite. Nic. //.

Material: Supergene zone

Composition: the pyrite massif sulphide is intensely fractured and transformed to a mineral phase with Pb (Pb, O, S) and a mineral phase with Cu and S, maybe chalcocite. It could be observed primary structures replaced by this Pb transformation phase. Less important fractures are filled by euhedral pyrite on a silicate matrix. Galena. Nic. //.

Minerology:

Pyrite are very fragmented Chalcocite Galena Silica Hematite in cracks Chalcopyrite

Ore microscopy

Sample: PX03-10 Primary and recrystallized pyrite. Nic. //. Domain with intense fragmentation of massif pyrite with interstitial galena. Nic.//.

Material: Supergene zone

Composition: The pyrite massif sulphide is intensely fractured. Formation of minor amounts of galena on silicate matrix veins.

Minerology:

Pyrite Covellite filling cracks in pyrite. Nic. //. Galena Covellite Silica

Ore microscopy

Sample: PX03-11 Texture of sample. Nic. //. Tetrahedrite-Tennantite replaced pyrite. Nic. //.

Material: Supergene zone

Composition: The pyrite massif sulphide is intensely fractured. Formation of minor amounts of galena on silicate matrix veins.

Domain with intense fragmentation of massif Digenite. Nic. //. Minerology: pyrite with interstitial galena. Nic. //.

Pyrite Galena Tetrahedrite-Tennantite Chalcocite Digenite

Ore microscopy

Sample: PX03-12 Recrystallized pyrite in galena. Nic. //. Chalcopyrite (yellow); Chalcocite (light blue); digenite (dark blue). Nic. //.

Material: Massive sulphide

Layers of massive pyrite and sphalerite. Composition:

Minerology: Pyrite in layers and euhedral crystals

Arsenopyrite in euhedral crystals

Sphalerite Galena interstitial or filling fractures Galena and sphalerite. Nic. //. Chalcopyrite interstitial or filling fractures Chalcocite Digenite Tetrahedrite-Tennantite

Ore microscopy

Sample: PX03-13 Fragmented pyrite. Nic. //. Recrystallized pyrite and chalcocite. Nic. //.

Material: Massive sulphide

Composition: Homogeneous pyrite massif sulphide that was brecchiated with the filling basically formed by pyrite fragments and tetrahedrite-tenantite and/or chalcocite on a silicate matrix. Massif sulphide exhibit primary textures as oolitic and radiated features. The brecchiated veins can reach dimensions of cm scale size. Recrystallized pyrite and chalcocite. Nic. //. Oolitic texture of pyrite. Nic. //.

Minerology: Pyrite Galena Tetrahedrite-Tennantite Chalcocite Digenite Bornite Sphalerite

Ore microscopy

Sample: PX03-14 Chalcocite. Nic. //. Fragmented pyrite. Nic. //.

Material: Massive sulphide

Composition: the pyrite massif sulphide is intensely fractured and transformed to a mineral phase with Pb (Pb, O, S). Formation of minor amounts of galena and sphalerite on silicate matrix veins.

Minerology: Tetrahedrite-Tennantite vein. Nic. //. Galena. Nic. //. Pyrite Chalcocite Digenite Sphalerite Galena Tetrahedrite-Tennantite

Ore microscopy

Sample: PX04A-15 Layer of sphalerite. Nic. //. Arsenopyrite in euhedral crystals. Nic.//.

Material: Supergene

Composition: Textural domains of pyrite massif sulphide and bands of continuous sphalerite and galena embedding recrystallized euhedral crystals of pyrite and arsenopyrite.

Collomorphic pyrite. Nic. //. Galena in fracture. Nic. //. Minerology:

Pyrite in layers and euhedral crystals Sphalerite interstitial or filling fractures Galena interstitial or filling fractures Arsenopyrite in euhedral crystals

Chalcopyrite as inclusion or disseminated

Sphalerite inclusions on arsenopyrite

Ore microscopy

Sample: PX04A-16 Layer of sphalerite and galena with fragments of Sphalerite with inclusions of chalcopyrite. pyrite. Nic. //.

Material: Massive sulphide

Composition: Textural domains of pyrite massif sulphide and bands of continuous sphalerite and galena embedding recrystallized euhedral crystals of pyrite and arsenopyrite. Chalcopyrite. Nic. //. Massive pyrite with euhedral arsenopyrite.

Minerology:

Pyrite in layers and euhedral crystals Sphalerite interstictial or filling fractures Galena interstictial or flling fractures Arsenopyrite in euhedral crystals Tetrahedrite-Tennantite Chalcopyrite

Ore microscopy

Sample: PX04A-17

Collomorphic pyrite . Nic. //. Layered texture. Nic. //. Material: Massive sulphide

Composition: Textural domains of pyrite massif sulphide and bands of continuous sphalerite and galena embedding recrystallized euhedral crystals of pyrite and arsenopyrite.

Minerology:

Pyrite in layers and euhedral crystals Sphalerite interstitial or filling fractures Galena interstitial or filling fractures Chalcocite Arsenopyrite in euhedral crystals Chalcopyrite

Ore microscopy

Sample: PX08-18 Pyrite compact zone. Nic. //. Pyrite fragmented zone. Nic. //.

Material: Supergene

Composition: Breccia with a rare tetrahedrite- tennantite interstitial on pyrite. Pyrite fragments with more fragmented zones and more compact zones.

Minerology: Chalcocite. Nic. //. Pyrite Digenite Tetrahedrite-tennantite

Ore microscopy

Sample: PX08-19 Euhedral pyrite. Nic. //. Galena, chalcocite, digenite and bornite (light brown). Nic. //.

Material: Massive sulphide

Composition: Textural domains of pyrite massif sulphide and bands of continuous sphalerite and galena embedding recrystallized euhedral crystals of pyrite and arsenopyrite.

Minerology: Galena. Nic. //. Arsenopyrite. Nic. //.

Pyrite in layers and euhedral crystals Sphalerite interstitial or filling fractures Galena interstitial or filling fractures Arsenopyrite in euhedral crystals Chalcopyrite as inclusions Chalcocite Digenite Bornite

Ore microscopy

Sample: PX08-20 Chalcopyrite veins. Nic. //. Chalcocite (blue-grey) replacing chalcopyrite (yellow), bornite (pinkish-brown) in fracture on Material: Massive sulphide pyrite. Nic. //.

Composition: Brecciated massif sulphide, with very irregular boundaries, and infilling of chalcopyrite, tetrahedrite-tennantite on a silicate matrix. Pyrite reacts to produce tetrahedrite-tennantite.

Minerology:

Pyrite Sphalerite interstitial or filling fractures Chalcopyrite Chalcocite Digenite Arsenopyrite in euhedral crystals Tetrahedrite-tennantite. Bornite Covellite