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ARSENOPYRITE FeAsS
(iron arsenic sulphide)
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As01 – Fine-grained felted aggregates
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As01 |
Representing 28% of all Hellyer arsenopyrite Woven intergrowth of arsenopyrite (white) and sphalerite (mid-grey) hosted by clustered spherical melnikovite pyrite (cream) with interstitial chalcopyrite (yellow), tetrahedrite (greenish grey, centre right) and chlorite (dark) – observed in the central parts of the massive sulphide and thought to indicate arsenic replacement during intra-mound refining. Hellyer drillcore sample HL347 20.4m Image width 1.1mm |
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As02 – Fine-grained rhombs hosted
by pyrite
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As02 |
Representing 27% of all Hellyer arsenopyrite Clusters and aggregates of arsenopyrite rhombs (white) hosted by poorly crystallised semi-primitive pyrite (cream) with minor interstitial galena (light blue, centre) and sphalerite (mid-grey, lower centre) – observed in the central to upper parts of the massive sulphide and interpreted to be crystallisation of arsenopyrite from the contaminant arsenic present in pre-cursor melnikovite pyrite. Hellyer drillcore sample HL347 20.4m Image width 265µm |
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As03 – Coarse-grained rhombs
replacing pyrite
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As03 |
Representing 25% of all Hellyer arsenopyrite Coarse-grained aggregates of arsenopyrite (white) hosted by colloform pyrite (cream) with minor interstitial galena (light blue) and chalcopyrite (yellow, centre right), adjacent to massive annealed sphalerite (mid-grey, upper left) with chalcopyrite blebs and “disease” (yellow, upper left) – common in the arsenic-rich areas of the central to upper parts of the massive sulphide and thought to show replacement of pyrite by arsenic-rich solutions during the waning retraction phase of the hydrothermal system. Hellyer drillcore sample HL329 165.6m Image width 1.1mm |
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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Sulphide Deposit, unpublished PhD thesis,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.
