Diaboleite

Diaboleit is a rarely occurring mineral from the mineral class of halides. It crystallizes in the tetragonal crystal system with the chemical composition Pb2Cu (OH ) 4Cl2 and usually develops transparent to translucent crystals with tabular to prismatic habit and square or octagonal costume, but also massive aggregates of dark blue to bright sky blue color with light blue stroke color.

Uninjured crystal faces have a diamond-like luster on cleavage surfaces, however, more of a pearlescent luster.

Etymology and history

The mineral was named after the Greek word διά [ slide] for apart or different in reference to his relationship to Boleite, from which it differs significantly however by crystal form.

Was first discovered Diaboleit in the "Higher Pitts Mine" by Priddy in the English county of Somerset. He was described in 1923 by Leonard James Spencer ( 1870-1959 ) and Edgar Donald Mountain ( 1901-1985 ), who analyzed the composition

Type material of the mineral is in the Natural History Museum of London under registration no. 1923.521 and the National Museum of Natural History in Washington DC in the U.S. under the registration no. 94813 preserved.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Diaboleit belonged to the mineral class of " halides " and then to the Department of " oxyhalides " where he along with Bideauxit, Boleite, Chloroxiphit, Cumengeit, Hämatophanit, Pseudoboleite and Yedlinit an independent group formed.

The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the Diaboleit in the class of " halides " and there in the department of " oxyhalides, hydroxyhalides and related double halides " one. This division, however, is further subdivided according to the nature of the metals involved, so that the mineral according to its composition in the subsection "With Pb, Cu, etc. " can be found, where it forms the unnamed group 3.DB.05 the only member.

The mainly common in English-speaking classification of minerals according to Dana assigns the Diaboleit in the class of " halides " and there in the department of " oxyhalides and hydroxyhalides ". Here he is the only member of the unnamed group 10:06:01 within the sub-division of " oxyhalides and hydroxyhalides with the formula AmBn (O, OH) p × q " to find.

Education and Locations

Diaboleit forms as a secondary mineral in highly weathered manganese or lead-and copper-containing ores. Accompanying minerals include Atacamit, Boleite, Caledonit, Chloroxiphit, Cerussite, Hydrocerussite, Leadhillit, Mendipit, paratacamite, Phosgenite and Wherryit.

Worldwide, Diaboleit so far (as of 2011) are detected in about 50 localities. Apart from its type locality Priddy, the mineral has been found in the Mendip Hills, in Holwell, Cranmore and cheddar in the county of Somerset, and at Padstow and Crantock in the county of Cornwall.

In Germany the mineral came to light in a cinder field at Richelsdorf in Hesse, Lower Saxony, and in Astfeld colliery in Essen Christian Levin in North Rhine-Westphalia. In Austria, the mineral is found so far only in a cinder field at Waitschach in Carinthia.

Other localities include Australia, Chile, France, Greece, Iran, Italy, South Africa and the United States of America (USA).

Crystal structure

Diaboleit crystallized tetragonal space group ( Raumgruppen-Nr. 99) with the lattice parameters a = 5.88 Å and c = 5.50 Å, and one formula unit per unit cell.