Scorzalite

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Scorzalite
Scorzalite-245653.jpg
Scorzalite from the Estaño Orcko mine, Potosí Department, Bolivia (6.8 x 5.7 x 5.1 cm)
General
Category Phosphate minerals
Formula
(repeating unit)
(Fe2+,Mg)Al2(OH,PO4)2
Strunz classification 08.BB.40
Crystal symmetry Monoclinic prismatic
H-M symbol: (2/m)
Space group: P 2/c
Unit cell a = 7.15 Å, b = 7.31 Å, c = 7.25 Å; β = 120.58°; Z = 2
Identification
Color Dark blue
Crystal habit Granular, massive, dipyramidal crystals
Crystal system Monoclinic
Twinning Multiple, lamellar
Cleavage Good on {110}, indistinct on {101}
Fracture Uneven
Mohs scale hardness 6
Luster Vitreous
Streak White
Diaphaneity Semitransparent
Specific gravity 3.33
Optical properties Biaxial (-)
Refractive index nα = 1.626 - 1.645 nβ = 1.654 - 1.674 nγ = 1.663 - 1.680
Birefringence δ = 0.037
Pleochroism Visible X = colorless; Y = Z = blue
2V angle Measured: 62°
Dispersion r < v perceptible
References [1][2][3]

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 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[edit]

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).[2]

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.[1]

References[edit]