Report on the Ore Mineralogy of Samples from the Lagoa Salgada, Volcanogenic Massive Sulfide (VMS) Deposit, Southern Portugal 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. 4 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. 5 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