a soft mineral, antimony sulfide, Sb 2 S 3 , lead-gray in color with a metallic luster, occurring in crystals, often acicular, or in bladed masses: the most important ore of antimony.
a mineral, hydrous sodium and calcium borate, NaCaB 5 O 9 ⋅8H 2 O, occurring in arid regions in the form of white acicular crystals: a major source of borax.
