A mineral occurring in modified acute rhombohedrons, containing sesquioxide of iron and oxide of lead, with phosphoric or arsenic acid, or both…

Mineralogy. A copper mineral found in amorphous green masses, now known to be a mixture consisting mainly of pseudomalachite. Now rare or disused.

A black or dark brown mineral which is a mixed oxide of zirconium, calcium, titanium, thorium, and other elements, occurring as small prisms or…

A rare mineral consisting of bismuth tungstate, occurring as pale yellow or green fine-grained masses.

Any of a group of very similar minerals which consist of mixed oxides of calcium, zirconium, and titanium, and occur as small black or brown…