Scorzalite

Scorzalite ((Fe2+,Mg)Al2(OH,PO4)2) is a dark blue phosphate mineral containing iron, magnesium, and aluminium phosphate. Scorzalite forms one endmember of a solid solution series with the lighter, more magnesium-rich lazulite.

Scorzalite
Scorzalite from the Estaño Orcko mine, Potosí Department, Bolivia (6.8 x 5.7 x 5.1 cm)
General
CategoryPhosphate minerals
Formula
(repeating unit)		(Fe2+,Mg)Al2(OH,PO4)2
IMA symbolScz[1]
Strunz classification8.BB.40
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupP2/c
Unit cella = 7.15 Å, b = 7.31 Å
c = 7.25 Å; β = 120.58°; Z = 2
Identification
ColorDark blue
Crystal habitGranular, massive, dipyramidal crystals
TwinningMultiple, lamellar
CleavageGood on {110}, indistinct on {101}
FractureUneven
Mohs scale hardness6
LusterVitreous
StreakWhite
DiaphaneitySemitransparent
Specific gravity3.33
Optical propertiesBiaxial (-)
Refractive indexnα = 1.626 - 1.645 nβ = 1.654 - 1.674 nγ = 1.663 - 1.680
Birefringenceδ = 0.037
PleochroismVisible X = colorless; Y = Z = blue
2V angleMeasured: 62°
Dispersionr < v perceptible
References[2][3][4]

Scorzalite crystallizes in the monoclinic system in a dipyramidal form. It has a Mohs hardness of 5.5-6 and a specific gravity of 3.4. It is infusible and insoluble in water, and only slightly soluble in warm hydrochloric acid.

Occurrence

It was first described in 1947 for an occurrence in the granite pegmatite in the Córrego Frio mine, Linópolis, Doce valley, Minas Gerais, Brazil. It was named for the Brazilian geologist Everisto Pena Scorza (1899–1969).[3]

It occurs as a secondary phase in pegmatites and kyanite (aluminium-rich) quartzites. Associated minerals include souzalite, triphylite, wyllieite, trolleite, apatite, lacroixite, berlinite, tourmaline, muscovite, feldspar and quartz.[2]

References
  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. Handbook of Mineralogy
  3. Mindat.org
  4. Webmineral data


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