Chloroxiphite

Chloroxiphite
Chloroxiphite crystal (dark green) embedded in mendipite. The bright blue material is diaboleite.
General
Category	Halide mineral
Formula (repeating unit)	Pb3CuO2Cl2(OH)2
IMA symbol	Cxp[1]
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	2+1⁄2
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	[2][3][4][5]

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.^[3] 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, , wulfenite, cerussite and hydrocerussite.^[5] 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.^[3]

References[]