Duftite

Duftit is a rarely occurring mineral from the mineral class of phosphates, arsenates and vanadates, specifically a lead-copper - arsenate with the chemical composition PbCu2 [ OH | AsO4 ]. It crystallizes in the orthorhombic crystal system and usually develops grapey mineral aggregates or crusty coatings, but also small, millimeter-sized crystals in a gray-green, olive-green or apple-green color.

Etymology and history

Was first described in 1920 by O. mineral Pufahl. He named it after G. fragrance, the then manager of the Otavi Mine in Tsumeb, Namibia.

Classification

In the old classification of minerals according to Strunz ( 8th edition ) of the Duftit belongs to the department of " anhydrous phosphates with foreign anions ", where it forms together with Adelit, Austinite, Gabrielsonit, Gottlobit, Kobaltaustinit, Konichalcit, Nickelaustinit and Tangeite the Adelitgruppe.

Since the new classification of minerals according to Strunz ( 9th edition ), however, this division is precisely divided by the size of the cations and the mineral is accordingly in the subdivision of " anhydrous phosphates with foreign anions, as well as medium-sized and mostly large cations (OH, etc.. ): RO 4 = 1:1 ".

The classification of minerals according to Dana leads with Duftit -beta ( 41.5.1.4 ) and Duftit -alpha ( 41.5.2.5 ) two virtually identical minerals in the department " Anhydrous Phosphates, etc., with hydroxyl or halogen with (AB ) 2 ( XO4 ) zq "on. However, According to other sources, Duftit -alpha is only a variety of Duftit -beta.

Education and Locations

Duftit forms as a secondary mineral in copper deposits. Accompanying minerals are mainly azurite, malachite and other secondary copper minerals, but also Bayldonit, Beudantite, calcite, cerussite, Mimetite, Mottramite, Olivenit and Wulfenite.

Apart from its type locality Tsumeb Duftit was found in Namibia still on Mountain Pass Kupferberg and in the Kombat Mine near Grootfontein.

Worldwide, for the mineral so far (as of 2009) the following localities registered: Cordoba in Argentina; New South Wales, Northern Territory, South Australia and Western Australia in Australia; Región de Atacama in Chile; Baden- Württemberg ( Black Forest), Bavaria ( Spessart ), Hesse (Odenwald ), Lower Saxony ( resin ), North Rhine -Westphalia ( Bergisch Land), Rhineland -Palatinate and Saxony (Erzgebirge) in Germany; different regions in France; at Laurion in Greece; England and Scotland in the United Kingdom; Piedmont, Sardinia and Tuscany in Italy; Kyūshū in Japan; Durango in Mexico; Carinthia and Tyrol in Austria; Lower Silesia ( Měděnec ) in Poland; Beja District ( Cerro do Algaré mine ) in Portugal; Andalusia in Spain; Glarus, Graubünden and Valais in Switzerland; Gauteng in South Africa; Bohemia in the Czech Republic; Ural in Russia; several regions of the U.S.; and Mashonaland in Zimbabwe.

Crystal structure

Duftit crystallizes in the orthorhombic crystal system, space group P 212121 with the lattice parameters a = 7.768 Å, b = 9.211 Å and c = 5.999 Å and four formula units per unit cell.