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CdS
Hexagonal
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| Figure 21-9. A greenockite assemblage from Sterling Hill. At left is botryoidal sphalerite, a cubic galena crystal, and elongate crystals of greenockite; field of view is 0.6 mm in maximum dimension. At right is a close-up view of a cluster of greenockite shown in the left photograph; field of view is 0.1 mm in maximum dimension. | ||
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Greenockite was noted as an unconfirmed species by Canfield (1899) and Palache (1908, 1935), but this material has been found to be a mixture including hawleyite. Kunz and Baskerville (1903) refer to a fluorescent greenockite from Franklin, but no data are given, and the description is of limited utility.
Greenockite is yellow to orange-yellow and occurs as powdery encrustations and thin films for the most part. The uncommon zincian greenockite described by Dunn (1979c) occurs in prismatic, subhedral crystals (Figures 21-9 and 21-10).
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| Figure 21-10. Elongate rough-surfaced crystals of greenockite on sphalerite from Sterling Hill. Field of view is 0.2 mm in maximum dimension. | ||
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Most local greenockite occurs intimately associated with other minerals, chiefly sphalerite, and thus historical observations of apparent fluorescence may be due to mixtures with other minerals.
Greenockite is a cadmium sulfide mineral isostructural with wurtzite. Local material has not been analysed, except for the crystals from Sterling Hill which Dunn (1979c) noted to have a Cd:Zn ratio of 3:2.
The “greenockite” reported by Palache (1935) from the Hamburg Mine, later part of the Franklin Mine, is shown here to be a mixture of sphalerite and hawleyite. True greenockite likely occurs here or elsewhere in the Franklin Mine in traces.
A number of greenockite specimens have been found at Sterling Hill, but this does not indicate a predominance of greenockite here relative to Franklin. Dunn (1979c) described a zincian greenockite occurring in small crystals associated with euhedral crystals of galena which, with greenockite, coat botryoidal sphalerite which in turn coats calcite (Figures 21-9 and 21-10). Numerous other occurrences have been found at Sterling Hill, particularly on the 1400 level, and most are associated with sphalerite and/or galena.
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| Copyright © 1995 by Pete J. Dunn |
Website
by Herb Yeates
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Link
to homepage
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This
page created: January 11, 2001 |
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