Tarapacáite is the mineral form of

potassium chromate Potassium chromate is the inorganic compound with the formula Potassium, K2Chromate ion, CrO4. This yellow solid is the potassium salt of the Chromate ion, chromate anion. It is a common laboratory chemical, whereas sodium chromate is important ...

with the

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

K₂ Cr O₄. 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 The Atacama Desert () is a desert plateau located on the Pacific Ocean, Pacific coast of South America, in the north of Chile. Stretching over a strip of land west of the Andes Mountains, it covers an area of , which increases to if the barre ...

before the

War of the Pacific The War of the Pacific (), also known by War of the Pacific#Etymology, multiple other names, was a war between Chile and a Treaty of Defensive Alliance (Bolivia–Peru), Bolivian–Peruvian alliance from 1879 to 1884. Fought over Atacama Desert ...

(1879–1883). Its type locality is Oficina Maria Elena, Maria Elena,

Tocopilla Province Tocopilla Province () is one of the three provinces in the northern Chilean region of Antofagasta (II). Its capital is the city of Tocopilla. Geography and demography According to the 2012 census by the National Statistics Institute (''INE''), t ...

, Antofagasta Region, Chile. It is unlikely to occur anywhere except in highly arid conditions as it is easily soluble in water.Handbook of Mineralogy (HOM - MSA) - Tarapacaite
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References

Potassium minerals Chromate minerals Orthorhombic minerals Minerals in space group 62 Minerals described in 1878 {{mineral-stub