Lópezite

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 [1][2]

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

  1. 1 2 3 4 5 Lopezite data on Mindat
  2. 1 2 3 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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