Asisite

• IMA 1987-003

Asisit is a very rarely occurring mineral from the mineral class of " halides ". It crystallizes in the tetragonal crystal system with the chemical composition Pb7SiO8Cl2 and has so far been found yellow to yellow-green (sometimes reddish yellow ) color with yellowish white line color only in the form of transparent, tabular, about 0.5 mm large crystals.

Etymology and history

Was first discovered Asisit 1987 in " Kombat Mine", which is on the " Asis farm " in the village of Grootfontein in Namibia.

Analyzed scientifically described and named after its type locality " Asis Farm" was the mineral by Roland C. Rouse, Donald R. Peacor, Pete J. Dunn, Alan J. Criddle, Chris J. Stanley and John Innes. Recognized by the IMA as an independent mineral it was still in the Fund year under the internal entry number (IMA ) 1987-003.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz was part of the mineral class of " halides " and then to the Department of " oxyhalides " where he, along with Blixit, Chubutit, Damarait, Ekdemit, Heliophyllit, Kombatit, Mendipit Mereheadit, Nadorite, Parkinsonit, Penfieldit, Perit, Philolithit, Pinalit, Sahlinit, Schwartzembergit, Seeligerit, Sundiusit, Symesit and Thorikosit formed a distinct group.

The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the Asisit also in the class of " halides " and there in the department of " oxyhalides, hydroxyhalides and related double halides " a. This division, however, is further subdivided according to the nature of the cations involved, so that the mineral "With Pb, Cu, etc. ," according to its composition in the subdivision to find where it is sold with Parkinsonit named after these two minerals group with the system number. 3.DB.40 forms.

The common in English-speaking classification of minerals according to Dana assigns the Asisit into the class of " halides " and there in the department of " oxyhalides and hydroxyhalides ". Here he is the only member of the unnamed group 10:02:07 within the subdivision " oxyhalides and hydroxyhalides having the formula A (O, OH) Xq ".

Education and Locations

Asisit forms in manganese silicate lenses in the near Sulfiderzkörpern. Accompanying minerals include barite, various chlorites, hematite, Hämatophanit, Jacobsite, native copper and Molybdophyllit.

So far (as of 2010), the mineral could be found only at its type locality, the " Kombat Mine" in Namibia.

Crystal structure

Asisit crystallized tetragonal in the space group with the lattice parameters a = 3.90 Å and c = 22.81 Å, and one formula unit per unit cell.