Chloroxiphite

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Chloroxiphite
Photograph of a mendipite sample with a dark crystal of chloroxiphite embedded in it and a smaller, bright blue diaboleite crystal at the chloroxiphite's top edge.
Chloroxiphite crystal (dark green) embedded in mendipite. The bright blue material is diaboleite.
General
Category Halide mineral
Formula
(repeating unit)
Pb3CuO2Cl2(OH)2
Strunz classification 3.DB.30
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group P21/m
Unit cell a = 6.6972(8) Å,
b = 5.7538(5) Å,
c = 10.4686(14) Å;
β = 97.747(10)°; Z = 2
Identification
Color Dull olive green to pistachio-green
Crystal habit Elongated, flatenned, striated and often curved crystals and groups
Cleavage Perfect on {101}, distinct on {100}
Tenacity Very brittle, friable
Mohs scale hardness
Luster Adamantine, resinous
Streak Light green yellow
Diaphaneity Transparent
Specific gravity 6.76 - 6.93
Optical properties Biaxial (-)
Refractive index nα = 2.160 nβ = 2.240 nγ = 2.250
Birefringence δ = 0.090
Pleochroism Visible: Y = yellowish brown; Z = bright emerald-green
2V angle Measured: ~70°
References [1][2][3][4]

Chloroxiphite is a rare olive green to pistacio green lead copper halide mineral with formula: Pb3CuO2Cl2(OH)2.

It was first discovered in 1923 in the Mendip Hills, Somerset, England associated with mendipite.[2] Like mendipite it is an oxychloride mineral and formed from the alteration of lead ore (galena) by secondary oxidation. In addition to mendipite, it occurs with diaboleite, parkinsonite, wulfenite, cerussite and hydrocerussite.[4] Its name comes from the Greek words (χλωρός) "green", describing its color, and (ζιφος) "blade" as its crystal form is long blade-like crystals that often show the growth pattern and time taken to form.[2]

References[edit]