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
Category Sulfate mineral
Formula
(repeating unit)
K2Cu2O(SO4)2
Strunz classification 7.BC.40
Crystal system Tetragonal
Crystal class Pyramidal (4)
H-M symbol: (4)
Space group I4
Unit cell a = 13.6 Å, c = 4.95 Å; Z = 2
Identification
Color Emerald-green, dark green, black
Crystal habit Acicular crystals elongated along [001], square cross section, commonly hollow; also as mosslike aggregates
Cleavage Perfect, parallel to elongation
Tenacity Brittle
Mohs scale hardness 2.5
Luster Vitreous to greasy
Streak Yellowish green
Diaphaneity Transparent to translucent
Specific gravity 3.0 - 3.1
Optical properties Uniaxial (+)
Refractive index nω = 1.583 nε = 1.695
Birefringence δ = 0.112
Pleochroism Distinct; O = pale green, yellowish green; E = deep green, pale yellowish green
Solubility Soluble 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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