1) Copper mineral 2) Nickel mineral
Found on
https://www.crosswordclues.com/clue/penroseite
Penroseite is a rare selenide mineral with formula (Ni,Co,Cu)Se2. It has a gray-steel color and black streak with a hardness of 3. It is an isometric mineral, 2/m{overline|3}. Penroseite was first discovered in 1925 in a Bolivian rhyolite. It was named for Richard Penrose (1863–1931), an economic geologist. Penroseite is a rare mineral found in ...
Found on
http://en.wikipedia.org/wiki/Penroseite
No exact match found.
