1) Monoclinic mineral
Found on
https://www.crosswordclues.com/clue/guettardite
Guettardite is a rare arsenic-antimony lead sulfosalt mineral with formula Pb(Sb,As)2S4. It forms gray black metallic prismatic to acicular crystals with monoclinic symmetry. It is a dimorph of the triclinic twinnite. ==Discovery and occurrence== It was first described in 1967 for an occurrence in the Taylor Pit, Madoc, Hastings County, Ontario, C...
Found on
http://en.wikipedia.org/wiki/Guettardite
No exact match found.
