Connellite

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Connellite
Connellite-54486.jpg
Connellite
General
Category Halide mineral
Formula
(repeating unit)
Cu19(OH)32(SO4)Cl4·3H2O
Strunz classification 3.DA.25
Crystal system Hexagonal
Crystal class Dihexagonal dipyramidal (6/mmm)
H-M symbol: (6/m 2/m 2/m)
Space group P63/mmc
Unit cell a = 15.78 Å, c = 9.10 Å; Z = 1
Identification
Color Azure blue, blue green
Crystal habit Clusters of divergent acicular crystals, fibrous, crusts
Cleavage None
Fracture Splintery
Tenacity Brittle
Mohs scale hardness 3
Luster Vitreous
Streak Pale green-blue
Diaphaneity Translucent
Specific gravity 3.36 to 3.41
Optical properties Uniaxial (+)
Refractive index nω = 1.724 - 1.746 nε = 1.738 - 1.758
Birefringence δ = 0.014
References [1][2][3][4]

Connellite is a rare mineral species, a hydrous copper chloro-sulfate, Cu19(OH)32(SO4)Cl4·3H2O, crystallizing in the hexagonal system. It occurs as tufts of very delicate acicular crystals of a fine blue color, and is associated with other copper minerals of secondary origin, such as cuprite and malachite. Its occurrence in Cornwall, England, was noted by Philip Rashleigh in 1802, and it was first examined chemically by Prof Arthur Connell FRSE in 1847, after whom it is named.

The type locality is Wheal Providence at Carbis Bay in Cornwall.[3] Outside Cornwall it has been found in over 200 locations worldwide including Namaqualand in South Africa and at Bisbee, Arizona (US).[3]

Connellite crystal structure: Color code: Cu: copper, S: olive, O: red, Cl: green; Cell: magenta

References[edit]

Public Domain This article incorporates text from a publication now in the public domainChisholm, Hugh, ed. (1911). "article name needed". Encyclopædia Britannica (11th ed.). Cambridge University Press.