Lópezite

Lopezite
Lopezite
General
Category	Sulfate minerals (chromate)
Formula; (repeating unit)	K2Cr2O7
Strunz classification	7.FD.05
Dana classification	35.2.1.1 Anhydrous chromates
Crystal system	Triclinic
Crystal class	Pinacoidal (1) ; (same H-M symbol)
Space group	P1
Identification
Color	Orange-red, red
Crystal habit	Granular or spherical in small crystals on the natural environment. Prismatic on lab grown crystals.
Cleavage	Perfect; [010] perfect, [100] distinct, [001] distinct
Mohs scale hardness	2+1⁄2
Luster	Vitreous
Streak	Light yellow
Diaphaneity	Transparent
Specific gravity	2.69
Pleochroism	Visible
Solubility	soluble in water
Other characteristics	Health risks: contains the carcinogenic and mutagenic chromate ion.
References

Lopezite is a rare red chromate mineral with chemical formula: K₂Cr₂O₇. It crystallizes in the triclinic crystal system.^[1]^[2]

It occurs as rare vug fillings in nitrate ores in association with tarapacáite (K₂CrO₄), dietzeite and ulexite in the Chilean Atacama and is reported from the Bushveld igneous complex of South Africa.^[1]^[2] Lopezite was first described in 1937 for an occurrence in Iquique Province, Chile and named after Chilean mining engineer Emiliano López Saa (1871–1959).^[1]

Most lopezite offered for sale to collectors is artificially produced.^[1] Synthetic varieties also exhibit monoclinic crystals.^[3]

References

^ ^a ^b ^c ^d ^e Lopezite data on Mindat
^ ^a ^b ^c Lopezite data in the Handbook of Mineralogy
^ Richard V. Gaines, H. Catherine W. Skinner, Eugene E. Foord, Brian Mason, and Abraham Rosenzweig: "Dana's new mineralogy", p. 692. John Wiley & Sons, 1997

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[Mindat-1] Lopezite data on Mindat

[Handbook-2] Lopezite data in the Handbook of Mineralogy

[3] Richard V. Gaines, H. Catherine W. Skinner, Eugene E. Foord, Brian Mason, and Abraham Rosenzweig: "Dana's new mineralogy", p. 692. John Wiley & Sons, 1997

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