MINERALS INDEX
Chloanthite |
| NiAs2 |
| Isometric |
Forms
a(100), o(111), and e(210).
Habit
Chloanthite is found both crystalline and massive. The crystals are rare, small, and much
distorted and are mainly octahedrons with minute modifying faces of the dodecahedron and
pyritohedron. The color of the massive mineral is dull steel-gray, but the crystal faces
are brilliant silver-white. The specific gravity is 6.833 (Koenig).
Composition
The chemical composition of chloanthite is shown by the following analysis:
Percent |
Molecular ratio |
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| As | 70.66 |
0.943* | 0.991 |
| S | 1.54 |
0.048* | |
| Ni | 18.63 |
0.318† | |
| Co | 6.37 |
0.108† | 0.467 |
| Fe | 2.31 |
0.041† | |
| Zn | trace |
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| CaCO3 | 0.89 |
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100.40 |
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[Figures noted with ‘*’ and ‘†’ are reflected in the values 0.991 and 0.467 shown, respectively]
The molecular ratio of (Ni,Co,Fe) to (As,S)–1:2.12–indicates a chloanthite very low in sulphur, with a ratio of nickel to cobalt, as shown by the analysis, of about 3 to 1.
Occurrence
Chloanthite is known only from the Trotter mine at
Franklin, the foregoing description being taken from a paper by Koenig (137). At a depth
of 340 feet the Trotter shaft passed through a segregation of nickel ores, comprising
chiefly chloanthite and niccolite and their oxidation products, together with calcite,
yellow sphalerite, and dark-purple fluorite. The chloanthite was in general intimately
intermixed with massive niccolite, and crystals were found only where it was in contact
with calcite. In one specimen a felted mass of bluish amphibole needles was cemented by
massive chloanthite, crystals of that mineral being implanted on the rounded surface.
Rammelsbergite
In some lists of Franklin minerals–Nason (153),
Kemp (152), Dana (146)–the name rammelsbergite appears. There is no good authority in
the published literature for the listing of this mineral, and it is doubtless a mistake
for chloanthite. (See appendix, b, page 130.)
Smaltite
No mention of smaltite has appeared in any publication on the district, hence its
inclusion in the list of Hoadley and Broadwell (235) is probably also to be considered a
mistake for chloanthite.
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Website
© by Herb Yeates 1997-2006.
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This
page created: August 12, 2006 5:53 PM
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