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TETRAHEDRITE (Cu,Ag,Zn,Fe)12(Sb,As)4S13
(complex copper antimony sulphide containing economic silver)
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Te01 – Remobilised segregations
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Te01 |
Representing 56% of all Hellyer tetrahedrite A large, coarse-grained segregation of remobilised tetrahedrite (greenish grey) with minor sphalerite (mid-grey) and chalcopyrite (yellow) in the “shadow zone” of a pyrite aggregate (cream, upper) and recrystallised quartz (dark, lower) – common in the central and upper parts of the massive sulphide showing migration of remobilised tetrahedrite to structural voids generated around brittle pyrite masses during the Devonian deformation. Hellyer drillcore sample HL382 96.1m Image width 2.1mm |
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Te02 - Remobilised into pyrite fractures
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Te02 |
Representing 29% of all Hellyer tetrahedrite Galena (light blue), chalcopyrite (yellow) and minor tetrahedrite (greenish grey) occupying a brittle fracture perpendicular to cleavage in the host pyrite (cream) – observed throughout the massive sulphide being the result of local remobilization of tetrahedrite into tensile cracks generated during the Devonian deformation. Hellyer drillcore sample HL342 127.6m Image width 530µm |
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Te03 - Irregular blebs hosted by massive
annealed sphalerite
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Te03 |
Representing 4.3% of all Hellyer tetrahedrite Irregularly-shaped blebs of tetrahedrite (greenish grey), chalcopyrite (yellow) and galena (light blue) with scattered euhedra of pyrite (cream) contained within massive annealed sphalerite (mid-grey) – restricted to the upper parts of the massive sulphide and interpreted to be the product of ductile recrystallisation of original primitive sphalerite/wurtzite/tetrahedrite during Devonian deformation. Hellyer drillcore sample HL353 26.2m Image width 1.1mm |
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Te04 - Interstitial to various textural
forms of pyrite
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Te04 |
Representing 3.9% of all Hellyer tetrahedrite Tetrahedrite (greenish grey) with minor galena (light blue) filling interstices between coarse-grained euhedral pyrite aggregates (cream) – observed throughout the massive sulphide due to local remobilisation of tetrahedrite during the Devonian deformation. Hellyer drillcore sample HL377 59.4m Image width 1.1mm |
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Te05 – Cores in spherical colloform
pyrite
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Te05 |
Representing 2.4% of all Hellyer tetrahedrite Tetrahedrite (greenish grey) occupying the cores of spherical colloform melnikovite pyrite (dark cream) with scattered pyrite (cream) overgrowths and euhedra, interstitial quartz (dark) and minor sphalerite (mid-grey, centre and centre top) – restricted to the upper parts of the massive sulphide and thought to be the result of local remobilisation of tetrahedrite into the more spongy cores of primitive melnikovite pyrite during the Devonian deformation. Hellyer drillcore sample HL349 8.0m Image width 530µm |
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Te06 – Late cross-cutting veinlets
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Te06 |
Representing 1.7% of all Hellyer tetrahedrite Narrow veinlets of tetrahedrite (greenish grey, across centre) cross-cutting pyrite (cream) aggregates, massive annealed sphalerite (mid-grey, upper right) and interstitial chalcopyrite (yellow) and sphalerite (mid-grey, upper left) – occurs throughout the massive sulphide cutting all Devonian textures and interpreted to show very late mobilisation of tetrahedrite during the late brittle faulting. Hellyer drillcore sample HL385 21.6m 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.
