Lópezite is a rare red chromate mineral with chemical formula: K2Cr2O7. It crystallizes in the triclinic crystal system.[2][3]

Lópezite
General
CategorySulfate minerals (chromate)
Formula
(repeating unit)
K2Cr2O7
IMA symbolLpz[1]
Strunz classification7.FD.05
Dana classification35.2.1.1 Anhydrous chromates
Crystal systemTriclinic
Crystal classPinacoidal (1)
(same H-M symbol)
Space groupP1
Identification
ColorOrange-red, red
Crystal habitGranular or spherical in small crystals on the natural environment. Prismatic on lab grown crystals.
CleavagePerfect
[010] perfect, [100] distinct, [001] distinct
Mohs scale hardness2+12
LusterVitreous
StreakLight yellow
DiaphaneityTransparent
Specific gravity2.69
PleochroismVisible
Solubilitysoluble in water
Other characteristicsHealth risks: contains the carcinogenic and mutagenic chromate ion.
References[2][3]

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.[2][3] Lópezite was first described in 1937 for an occurrence in Iquique Province, Chile and named after Chilean mining engineer Emiliano López Saa (1871–1959).[2]

Most commercially available lópezite is artificially produced.[2] Synthetic varieties also exhibit monoclinic crystals.[4]

References

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  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b c d e Lópezite data on Mindat
  3. ^ a b c Lópezite data in the Handbook of Mineralogy
  4. ^ 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