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Chapmanite



Chapmanite

Yellow-green earthy massive chapmanite
General
CategoryMineral
Chemical formulaFe2Sb(SiO4)2(OH)
Identification
ColorYellow, green, olive green
Crystal habitEarthy massive; granular
Crystal systemMonoclinic-domatic
CleavagePoor
FractureConchoidal to irregular
Mohs Scale hardness2.5
LusterNonmetallic, dull to adamantine
Refractive indexnα=1.850 nβ=1.950 nγ=1.960
PleochroismNone
StreakYellowish green
Specific gravity3.69-3.75

Chapmanite is a rare silicate mineral belonging to the nesosilicate group, discovered in 1924, and named in honour of the late Edward John Chapman, a geology professor at the University of Toronto. Chemically, it is an iron antimony silicate, closely related to bismutoferrite, and may contain aluminium impurities. It is closely associated with silver mines, most notably the Keeley mine in Ontario, Canada, found in quartz veinlets containing graphite in gneiss. It takes the form of a powdery, yellow-green, semitransparent solid, and leaves a streak of the same colour. Early German texts have referred to the mineral as antimon-hypochlorite.

Additional recommended knowledge

It was recently rediscovered in the southern hemisphere at the abandoned Argent lead mine in Bushveld series rocks of South Africa.

References

  • Mindat with location data
  • Webmineral data
  • Handbook of Mineralogy (PDF)
  • South African discovery Neues Jahrbuch fur Mineralogie-Monatshefte 2000 #2 pages: 85 - 90
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Chapmanite". A list of authors is available in Wikipedia.
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