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
CategorySulfate (chromate) mineral
Formula
(repeating unit)
Pb2O(CrO4)
IMA symbolPhc[1]
Strunz classification7.FB.05
Dana classification35.1.2.1 Anhydrous chromates
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupC2/m
Unit cella = 14 Å, b = 5.67 Å,
c = 7.13 Å; β = 115.22°; Z = 4
Identification
ColorDark red, bright red
Crystal habitTabular crystals; thin coatings, and massive
CleavagePerfect on {201}
TenacitySectile
Mohs scale hardness2+12
LusterAdamantine, resinous
StreakBrick-red
DiaphaneityTranslucent
Specific gravity5.75,[2] 7.01[3]
Optical propertiesBiaxial (+)
Refractive indexnα = 2.380, nβ = 2.440, nγ = 2.650
Birefringence0.270 (δ)
2V angle58° (measured)
Other characteristicsHealth risks: contains carcinogenic and mutagenic chromate ion
References[4][2][3][5]

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]

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85: 291–320.
  2. ^ a b c d Mindat.org Phoenicochroite on Mindat
  3. ^ a b Phoenicochroite in the Handbook of Mineralogy
  4. ^ Mineralienatlas
  5. ^ Phoenicochroite data on Webmin