Salpetre
Image: <bdi><a href="//commons.wikimedia.org/wiki/User:ComputerHotline" title="User:ComputerHotline">Thomas Bresson</a></bdi> (CC BY 3.0)
Mineral NameSalpetre
Chemical FormulaKNO₃
Mohs Hardness2
Crystal Systemorthorhombic
Lustervitreous
Streak Colorwhite
Cleavageperfect on {011}, distinct on {110}
Fractureconchoidal
Specific Gravity2.11
Colorswhite, colorless, gray, yellowish
Transparencytransparent
Type LocalityGlobal, often found as efflorescence in caves or arid soils
Mineral GroupNitrates
Usesfertilizer, gunpowder, food preservation, pyrotechnics
Associated Mineralsgypsum, halite, nitratine
Rarityuncommon
Description
A delicate cluster of fine, needle-like to fibrous, translucent white crystals, possibly with a yellowish base, forming an efflorescence.
Geological Context
Salpetre forms as an evaporite mineral, often as efflorescence on cave walls, in arid soils, or in areas with decaying organic matter and potassium-rich rocks where bacterial action converts nitrogenous compounds.
