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!
Most bornite from Bristol is massive vein material in layers and stringers throughout the vein system, and as rounded blebs in white calcite or on quartz matrix. Crystals rare and specimens not as prevalent as chalcocite.
Habit:
typically dodecahedral, less commonly in cubes showing slight modifications. Most crystals are slightly to severely rounded.
Colour:
dull black, with blue patina
Quality for species:
Excellent - world class for species or very significant. (!!)
Bristol Copper Mine, Bristol, Hartford County, Connecticut, USA