Salpetre (Potassium Nitrate)
Image: <bdi><a href="//commons.wikimedia.org/wiki/User:ComputerHotline" title="User:ComputerHotline">Thomas Bresson</a></bdi> (CC BY 3.0)
Mineral NameSalpetre (Potassium Nitrate)
Chemical FormulaKNO₃
Mohs Hardness2
Crystal Systemorthorhombic
Lustervitreous
Streak Colorwhite
Cleavageperfect on {011}
Fractureconchoidal
Specific Gravity2.11
Colorswhite, colorless, grayish
Transparencytransparent
Type LocalityWorldwide in arid regions, caves, and as efflorescence
Mineral GroupNitrates
Usesfertilizer, gunpowder, food preservation, pyrotechnics
Associated Mineralsgypsum, halite, limestone
Rarityuncommon
Description
This image displays a delicate, white, fibrous growth of salpetre, appearing as a fluffy or hair-like efflorescence on a surface. Small yellowish and dark specks are interspersed within the translucent fibers.
Geological Context
Salpetre typically forms as an evaporite mineral in arid climates, often found in caves or as efflorescence on the surface of rocks (especially limestone) or soil, where it crystallizes from nitrate-rich solutions. It can also be formed by the decomposition of organic matter in the presence of potassium-bearing minerals.
