Boleite

Boleite is a rarely occurring mineral from the mineral class of " halides ". It crystallizes in a cubic crystal system having a chemical composition KPb26Cu24Ag9 (OH) 48Cl62 and developed almost entirely translucent to transparent crystals having a cubic habit, or combinations of cubic shapes. There is often Boleite fused with the Cumengeit or Pseudoboleite oriented ( epitaxial ). The areas of the characteristic intense blue crystals exhibit weak vitreous luster on cleavage surfaces contrast shimmering pearlescent.

With a Mohs hardness of 3 to 3.5 Boleite includes not only the reference to the soft mineral calcite minerals that can be scratched with a copper coin.

Special Features

Boleite is water soluble and therefore must be kept protected from moisture.

Etymology and history

Was first discovered Boleite in Santa Rosalia ( Boleo ) in the Mexican province of Baja California Sur and described in 1891 by François Ernest Mallard and Edouard Cumenge who named the mineral after its type locality.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Boleite belonged to the mineral class of " halides " and then to the Department of " oxyhalides " where he along with Bideauxit, Chloroxiphit, Cumengeit, Diaboleit, 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 Boleite also in the class of " halides ", there, however, in the advanced section of the " oxyhalides, hydroxyhalides and related double halides " a. This department is also further divided according to the conditions prevailing in the interconnect metals, so that the mineral "With Pb, Cu, etc. ," according to its composition in the subdivision is to find where it is the only member of the unnamed group 3.DB.15 forms.

The mainly common in English-speaking classification of minerals according to Dana assigns the Boleite into the class of " halides " and then in the Department also extended the " oxyhalides and hydroxyhalides ". Here he can be found as the only member of the unnamed group 10.06.01 within the subdivision " oxyhalides and hydroxyhalides with the formula AmBn (O, OH) p × q ".

Education and Locations

Boleite forms as a secondary mineral by the reaction of chlorine compounds with primary sulfides in the oxidation zone of copper deposits in arid climates. Accompanying minerals are next Cumengeit and Pseudoboleite, you still Atacamit, anglesite, Bideauxit, Cerussite, Caledonit, gypsum, Leadhillit, matlockite, paratacamite, Paralaurionit and Phosgenite.

Worldwide, Boleite so far (as of 2011) are detected in about 55 localities. Apart from its type locality of Santa Rosalia ( Boleo ) in Baja California Sur, the mineral occurred in Mexico still at Arizpe, Sonora. In Boléo the biggest Boleitwürfel were having an edge length of up to 3.5 cm found.

The only known locality in Germany, the slag heap of the Herzog- Julius- hut in Astfeld in Lower Saxony Harz Mountains.

Other localities are Broken Hill in Australia; the Chilean Antofagasta and Tarapacá regions; Poullaouen and the Pradet in France; the Greek region of Attica; Anarak in Iran; the Italian province of Livorno; several places in England in the United Kingdom ( UK), and many places in Arizona, California, Montana, Nevada and Washington in the United States of America (USA).

Crystal structure

Boleite crystallized cubic space group ( Raumgruppen-Nr. 221 ) with the lattice parameters a = 15.29 Å, and one formula unit per unit cell.