Phoenicochroite

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Phoenicochroite
Phoenicochroite-212833.jpg
Deep red Phoenicochroite cystal, with orange-yellow schwartzembergite. San Francisco Mine, Tocopilla Province, Chile. Photo width 1.5 mm.
General
Category Chromate mineral
Formula
(repeating unit)
Pb2O(CrO4)
Strunz classification 7.FB.05
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group C2/m
Unit cell a = 14 Å, b = 5.67 Å,
c = 7.13 Å; β = 115.22°; Z = 4
Identification
Color Dark red, bright red
Crystal habit Tabular crystals; thin coatings, and massive
Cleavage Perfect on {201}
Tenacity Sectile
Mohs scale hardness
Luster Adamantine, resinous
Streak Brick-red
Diaphaneity Translucent
Specific gravity 7.01
Optical properties Biaxial (+)
Refractive index nα = 2.380, nβ = 2.440, nγ = 2.650
Birefringence 0.270 (δ)
2V angle 58° (measured)
References [1][2][3][4]

Phoenicochroite, also known as melanochroite, is a lead chromate mineral with formula Pb2OCrO4. It forms striking orange red crystals. It was first discovered in 1839 in Beryozovskoye deposit, Urals, Russia.[2] It is named from the Greek word φοίυικος for "deep red" and χρόα for "color," in allusion to its color.[2]

References[edit]