Diaboleite
Diaboleite | |
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Diaboleite at the American Museum of Natural History, in New York City | |
General | |
Category | Halide mineral |
Formula (repeating unit) | Pb2CuCl2(OH)4 |
Strunz classification | 3.DB.05 |
Dana classification | 10.6.1.1 |
Crystal system | Tetragonal |
Crystal class |
Ditetragonal pyramidal (4mm) H-M symbol: (4mm) |
Space group | P4mm |
Unit cell | a = 5.880, c = 5.500 Å, Z = 1[1] |
Identification | |
Color | Blue |
Crystal habit | As square tabular crystals, thin plates, massive |
Cleavage | Perfect on {001} |
Fracture | Conchoidal |
Tenacity | Brittle |
Mohs scale hardness | 2.5 |
Luster | Adamantine, pearly on cleavages[1] |
Streak | Pale blue[1] |
Diaphaneity | Transparent to translucent[1] |
Density | 5.41 to 5.43 g/cm3 |
Optical properties | Uniaxial (-) |
Refractive index | nω = 1.980, nε = 1.850 |
Birefringence | δ = 0.130 |
Absorption spectra | O > E, in thick fragments[1] |
Solubility | Completely soluble in nitric acid |
References | [2] |
Diaboleite is a blue-colored mineral with formula Pb2CuCl2(OH)4. It was discovered in England in 1923 and named diaboleite, from the Greek word διά and boleite, meaning "distinct from boleite".[2] The mineral has since been found in a number of countries.
Description
Diaboleite is deep blue in color and pale blue in transmitted light. The mineral occurs as tabular crystals up to 2 cm (0.8 in) in size, as subparallel aggregates, or it has massive habit. Vicinal forms of the tabular crystals have a square or octagonal outline and rarely exhibit pyramidal hemihedralism.[1]
Formation
Diaboleite occurs in manganese oxide ores, as a secondary mineral in lead and copper oxide ores, and in seawater-exposed slag. Diaboleite has been found in association with atacamite, boleite, caledonite, cerussite, chloroxiphite, hydrocerussite, leadhillite, mendipite, paratacamite, phosgenite, and wherryite.[1]
A study in 1986 synthesized diaboleite crystals up to 0.18 mm (0.0071 in) in size using two different methods. The study demonstrated that diaboleite is a low-temperature phase, that is stable under hydrothermal conditions at temperatures less than 100 to 170 °C (212 to 338 °F). At higher temperatures, the first stable mineral to form is cumengeite.[3]
History
In 1923, diaboleite was discovered at Higher Pitts Mine in the Mendip Hills of Somerset, England,[2] and described by L. J. Spencer and E.D. Mountain.[4] The study of the similar mineral boleite was perplexing at the time and this new mineral only compounded the difficulty. As insufficient material was available for a full investigation, Spencer and Mountain named it diaboleite, meaning "distinct from boleite", out of "desperation".[5]
The mineral was grandfathered as a valid mineral by the International Mineralogical Association as it was described prior to 1959.[2]
Distribution
As of 2012, diaboleite has been found in Australia, Austria, Chile, France, Germany, Greece, Iran, Italy, Russia, South Africa, the UK and the US.[1][2] The type material is held at the Natural History Museum in London and the National Museum of Natural History in Washington, D.C.[1]
References
- Citations
- Bibliography
- Spencer, L. J.; Mountain, E. D. (September 1923). "Diaboleite" (PDF). Mineralogical Magazine. Mineralogical Society. 20 (102): 78–80. doi:10.1180/minmag.1923.020.102.01.
- Winchell, R. E.; Wenden, H. E. (November 1968). "Synthesis and Study of Diaboleïte" (PDF). Mineralogical Magazine. Mineralogical Society. 36 (283): 933–939. doi:10.1180/minmag.1968.283.036.03.
Further reading
- Cooper, Mark A.; Hawthorne, Frank C. (October 1995). "Diaboleite, Pb2Cu(OH)4Cl2, a defect perovskite structure with stereoactive long-pair behavior of Pb (super 2+)". Canadian Mineralogist. 33 (5): 1125–1129. (subscription required)
- Palache, Charles (October 1941). "Diabloeite from Mammoth Mine, Tiger, Arizona" (PDF). American Mineralogist. Mineralogical Society of America. 26 (10): 605–612.
External links
- Media related to Diaboleite at Wikimedia Commons