Piypite

Piypite is a rare potassium, copper sulfate mineral with formula: K2Cu2O(SO4)2. It crystallizes in the tetragonal system and occurs as needlelike crystals and masses. Individual crystals are square in cross-section and often hollow. It is emerald green to black in color with a vitreous to greasy luster.[2][3]

It was first described in 1982 for an occurrence in the Main Fracture of the Tolbachik volcano, Kamchatka Oblast, Russia. It has also been reported from Mount Vesuvius, Italy, and in a slag deposit in the Bad Ems District in the Rhineland-Palatinate, Germany.[2][1] It occurs as a sublimate phase in a fumarole environment. Associated minerals include halite, sylvite, langbeinite, tenorite, hematite, tolbachite, dolerophanite, urusovite, aphthitalite, ponomarevite, cotunnite, chalcocyanite, sofiite, euchlorine, averievite, fedotovite, alarsite, alumoklyuchevskite, nabokoite and lammerite at the type locality in Kamchatka. On Vesuvius it occurs with paratacamite.[2]

Piypite
Piypite-88672
Green acicular crystals of piypite
General
CategorySulfate mineral
Formula
(repeating unit)
K2Cu2O(SO4)2
Strunz classification7.BC.40
Crystal systemTetragonal
Crystal classPyramidal (4)
H-M symbol: (4)
Space groupI4
Unit cella = 13.6 Å, c = 4.95 Å; Z = 2
Identification
ColorEmerald-green, dark green, black
Crystal habitAcicular crystals elongated along [001], square cross section, commonly hollow; also as mosslike aggregates
CleavagePerfect, parallel to elongation
TenacityBrittle
Mohs scale hardness2.5
LusterVitreous to greasy
StreakYellowish green
DiaphaneityTransparent to translucent
Specific gravity3.0 - 3.1
Optical propertiesUniaxial (+)
Refractive indexnω = 1.583 nε = 1.695
Birefringenceδ = 0.112
PleochroismDistinct; O = pale green, yellowish green; E = deep green, pale yellowish green
SolubilitySoluble in water, leaves residue
References[1][2][3][4]

References

  1. ^ a b Piypite on Mindat.org
  2. ^ a b c d Piypite in the Handbook ov Mineralogy
  3. ^ a b Piypite data on Webmineral
  4. ^ Mineralienatlas

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