THE MINERAL STIBNITE

Chemistry: Sb2S3, Antimony Sulfide
Class: Sulfides
Uses: An ore of antimony and as mineral specimens.
Specimens

Stibnite is a classic mineral species with fine crystal clusters and long curved crystals being the pride of many collectors. The slender curved metallic blades of stibnite can resemble arabian swords. The curving of the long bladed crystals is due to twinning where one twin plane bends the crystal one direction and another twin plane bends it in the other direction. This can occur numerous times down the length of one crystal. Stibnite's crystal clusters are admired for their distinctive look with dozens of accicular or bladed crystals jutting out in many divergent directions.

PHYSICAL CHARACTERISTICS:

Color is steel gray to silver.
Luster is metallic.
Transparency crystals are opaque.
Crystal System is orthorhombic; 2/m 2/m 2/m
Crystal Habits include bladed or acicular crystals often bent or curved due to twinning, also granular and massive.
Cleavage is perfect in the lengthwise direction.
Fracture is irregular.
Hardness is 2
Specific Gravity is approximately 4.6+ (average for metallic minerals)
Streak is a dark gray.
Other Characteristics: striated lengthwise sometimes deeply, luster brighter on cleavage surfaces and crystals slightly flexible.
Associated Minerals include quartz, calcite, gold, arsenopyrite and other sulfides.
Notable Occurrences include Hunan province, China; Japan; Germany; Brazil; Peru and South Africa.
Best Field Indicators are crystal habit, softness and flexibility.