Specimen of the Month: Stibnite
Stibnite is an antimony sulfide. Soft and lead gray in color, it forms in hydrothermal deposits as needle- or pencil-like clusters. Some of the crystal forms are unique, forming clusters of striated metallic crystals radiating with angular or curved shapes. (See photo below.)
Stibnite is a source of the metal antimony, which has applications in lead-acid batteries and microelectronics. Stibnite may contain some arsenic and yellow sulfur. The red minerals in the specimen depicted in the last two photos below are realgar, an arsenic sulfide, and cinnabar, a mercury sulfide. Some of the most classic localities for specimens are in Romania, Japan, and China.
The large stibnite crystal from China in the KGS collection was purchased many years ago and shows many distinguished characteristics of stibnite. The smaller specimen with realgar was obtained from the Red Devil Mine in Alaska and donated to KGS.