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!
'Columbite-(Fe)-Columbite-(Mn) Series' (not an IMA approved species)
Formation:
Primary
Comments:
Good prismatic crystals formed in quartz, also hand-sized subhedral masses with striations from neighboring muscovite. Januzzi (1976) reports that a beryl crystal with a large columbite crystal projecting from it was donated to the American Museum of Natural History in New York City. The ID is generic, at least one crystal was tested using Raman spectroscopy and the best match is tantalite-(Fe) (see entry). A crystal formerly in the Bill Shelton collection has a specific gravity of 6.7, making it clearly a columbite species.
Biermann Quarries, Bethel, Fairfield County, Connecticut, USA