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SPHALERITE ZnS (zinc
sulphide)
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Sp01 – Annealed masses
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Sp01 |
Representing 64% of all Hellyer sphalerite Bands of massive annealed sphalerite (mid-grey) containing uniformly distributed blebs of galena (light blue), chalcopyrite (yellow) and tetrahedrite (greenish grey, lower right) and scattered fine-grained subhedra of pyrite (cream, centre) – mostly restricted to the upper parts of the massive sulphide and interpreted to be the product of ductile recrystallisation of original primitive sphalerite/wurtzite during Devonian deformation. (The dark areas are voids they may in part be polishing imperfections). Hellyer drillcore sample HL353 26.2m Image width 1.1mm |
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Sp02 – Inclusion-free interstitial
to host pyrite
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Sp02 |
Representing 14% of all Hellyer sphalerite Late interstitial infilling of inclusion-free sphalerite (mid-grey, centre) inside earlier colloform overgrowths of pyrite (cream, surrounding central sphalerite), fine-grained crystalline aggregates of pyrite (cream, right), earlier sphalerite (mid-grey, upper right), remobilised interstitial galena (light blue) and minor arsenopyrite (white, right) – interpreted to show late deposition of refined sphalerite into available voids during the waning retraction phase of the hydrothermal system. Hellyer drillcore sample HL382 85.9m Image width 530µm |
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Sp03 – Remobilised into pyrite
fractures
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Sp03 |
Representing
6.9% of all Hellyer sphalerite Hellyer drillcore sample HL348 31.9m Image width 2.1mm |
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Sp04 – Hexagonal pseudomorphs
after wurtzite with chalcopyrite “disease”
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Sp04 |
Representing 6.2% of all Hellyer sphalerite Hexagonal pseudomorphs of sphalerite (mid-grey, centre) containing fine-grained blebs of chalcopyrite “disease” (yellow) aligned on crystal planes, encased in pyrite (cream, upper) and cut by remobilised sphalerite (mid-grey, lower right) and chalcopyrite (yellow, lower right) – common in the central parts of the massive sulphide and interpreted to be original primitive hexagonal wurtzite (low temperature form of sphalerite) that transformed to sphalerite with exsolution of chalcopyrite. Hellyer drillcore sample HL221 17.9m Image width 265µm |
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Sp05 – Colloform growths
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Sp05 |
Representing 2.8% of all Hellyer sphalerite Preserved colloform growths of sphalerite (mid-grey) with alternating colloform pyrite (cream) and accessory corroded ankerite (dark grey, left centre) and quartz (dark, lower right) – mainly observed in the central parts of the massive sulphide with other preserved primitive textural forms showing layered deposition of sulphides in open space. Hellyer drillcore sample HL348 30.8m Image width 2.1mm |
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Reference: McArthur, G.J. (1996) Textural Evolution of the Hellyer Massive
Sulphide Deposit, unpublished PhD thesis,
Univ.of Tas., 3 vols.
Higher
resolution images are available by contacting MODA gary@modapl.com.au
This page is under continuing construction.
