Vote for your favorite mineral in #MinCup26! - Sphalerite vs. Anorthite Both zinc ore Sphalerite and calcium plagioclase feldspar Anorthite have perfect cleavage that will split cleanly if you hit them with a hammer, but only one can claim a larger split of your votes!
The Bitter Creek mine is the type locality for montroseite (Weeks and others, 1950, 1953). The microscopic, bladed prismatic crystals and compact crystalline aggregates of montroseite were also noted by Heyl (1957).
Bitter Creek Mine, Paradox Valley, Montrose County, Colorado, USA