Alloclasite () is a
sulfosalt mineral (
IMA symbol
A symbol is a mark, sign, or word that indicates, signifies, or is understood as representing an idea, object, or relationship. Symbols allow people to go beyond what is known or seen by creating linkages between otherwise very different conc ...
: Acl). It is a member of the
arsenopyrite group. Alloclasite crystallizes in the
monoclinic system and typically forms as
columnar to radiating
acicular prismatic clusters. It is an opaque steel-gray to silver-white, with a
metallic luster and a black
streak. It is
brittle with perfect cleavage, a
Mohs hardness of 5 and a
specific gravity of 5.91–5.95.
[http://rruff.geo.arizona.edu/doclib/hom/alloclasite.pdf Handbook of Mineralogy]
It was first described in 1866 for an occurrence in
Romania. Its name is derived from
Greek for "other" and "to break," in reference to its distinct cleavage which distinguished it from the similar appearing mineral
marcasite.
[
The mineral is monoclinic in the ''P21'' space group.]
References
Cobalt minerals
Iron minerals
Sulfosalt minerals
Monoclinic minerals
Minerals in space group 4
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