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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
CategoryHalide mineral
Formula
(repeating unit)
Pb3CuO2Cl2(OH)2
IMA symbolCxp[1]
Strunz classification3.DB.30
Crystal systemMonoclinic
Crystal classPrismatic (2/m)
(same H-M symbol)
Space groupP21/m
Unit cella = 6.6972(8) Å,
b = 5.7538(5) Å,
c = 10.4686(14) Å;
β = 97.747(10)°; Z = 2
Identification
ColorDull olive green to pistachio-green
Crystal habitElongated, flatenned, striated and often curved crystals and groups
CleavagePerfect on {101}, distinct on {100}
TenacityVery brittle, friable
Mohs scale hardness2+12
LusterAdamantine, resinous
StreakLight green yellow
DiaphaneityTransparent
Specific gravity6.76–6.93
Optical propertiesBiaxial (−)
Refractive indexnα = 2.160 nβ = 2.240 nγ = 2.250
Birefringenceδ = 0.090
PleochroismVisible: Y = yellowish brown; Z = bright emerald-green
2V angleMeasured: ~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, parkinsonite, 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

[edit]
  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. ^ Mineralienatlas
  3. ^ a b c Mindat.org
  4. ^ Webmineral.com
  5. ^ a b Handbook of Mineralogy