Tarapacaite

Tarapacáite is the mineral form of potassium chromate with the chemical formula K₂CrO₄. It forms bright yellow crystals and was discovered in 1878. It is named for the former Tarapacá Province, Peru; nowadays belonging to Chile. The boundaries between Peru, Bolivia and Chile were vague in the Atacama Desert before the War of the Pacific (1879–1883). Its type locality is Oficina Maria Elena, Maria Elena, Tocopilla Province, Antofagasta Region, Chile. It is unlikely to occur anywhere except in highly arid conditions as it is easily soluble in water.^[1][2][3]

Tarapacáite
General
Category	Sulfate minerals
Formula	K2(CrO4)
Strunz classification	7.FA.05
Dana classification	35.2.1.1.1 Anhydrous chromates
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m)
Space group	Pnam (no. 62)
Identification
Color	Bright yellow, yellow-orange
Crystal habit	Thick tabular
Cleavage	Distinct/good On {001} and {010}, distinct
Diaphaneity	Transparent
Specific gravity	2.735
Solubility	Soluble in water
Other characteristics	Health risks: contains the carcinogenic and mutagenic chromate ion
References	[1]