Adamite

Adamite is a rarely occurring mineral from the mineral class of " phosphates, arsenates and vanadates ." It crystallizes in the orthorhombic crystal system with the chemical composition of Zn2 [ OH | AsO4 ] and developed primarily short to long prismatic crystals often in the form of a double pyramid ( octahedron ). It can also have the habit of speroidischen mass. Its color varies between colorless, yellow, yellow green, green, pink and purple.

Special Features

Adamin lights green to yellow- green to UV light.

Together with Olivenit it forms a mixed batch with increasing copper content after Olivenit. Since Cuproadamin occurs within the mixed batch, it is variously not recognized as a distinct variety.

Etymology and history

Was first described in 1866 by French chemist Adamin and mineralogist Charles Friedel ( 1832-1899 ). He named the mineral after the French mineralogist Gilbert Joseph Adam (1795-1881), who in 1866 first found it in Chañarcillo / Atacama Region in Chile.

Classification

In the classification by Strunz Adamin is classified in the phosphates, arsenates and vanadates. It is counted among the phosphates, arsenates and vanadates with other anions, but without water of crystallization. In the eighth edition, it forms with Eveit, Libethenit, Olivenit, Paradamin, Tarbuttit and Zincolibethenit the Libethenit series, in the ninth edition with Auriacusit, Eveit, Libethenit, Olivenit, Zinkolibethenit and Zinkolivenit a subgroup of phosphates, arsenates and vanadates with medium-sized cations (OH, etc.) and a proportion of the anions and RO4 of less than or equal to 1:1.

In the classification of minerals according to Dana it forms with Libethenit, Olivenit, Eveit, Zinkolibethenit and Zinkolivenit a subset of Anhydrous Phosphates, etc., with hydroxyl or halogen ions and a composition A2 ( XO4 ) Zq.

Varieties and modifications

The connection Zn2 [ OH | AsO4 ] is dimorphic and is found in nature in addition to the orthorhombic Adamin still as triclinic crystallizing Paradamin ago.

In the varieties of aluminum - Adamite, Cuproadamin, Cobaltadamin, Manganadamin and Nickeladamin the zinc contained in the Adamite is partially replaced by the element specified in the Varietätnamen.

Education and Locations

Adamite is found together with Aurichalcit, hemimorphite, and smithsonite Konichalcit in the oxidation zone arsenic- rich solutions or in zinc deposits.

There are a total of 175 localities (as of April 2010) of the Adamins known. These include, among other things, Cap Garonne in France, Laurion in Greece, Mapimí / Durango in Mexico and Tsumeb in Namibia.

Crystal structure

Adamin crystallizes in the orthorhombic crystal system, space group Pnnm with the lattice parameters a = 8.30 Å, b = 8.51 Å and c = 6.04 Å and four formula units per unit cell.