Chalcophyllite

Chalkophyllit (deprecated and copper mica ) is a rarely occurring mineral from the mineral class of phosphates. It crystallizes in the trigonal crystal system with the chemical composition Cu9Al [( OH) 12 | (SO4) 1.5 | ( AsO4 ) 2] • 18 H2O and usually develops scaly, fan-shaped or massive aggregates, but also crusty coatings and rarely transparent to translucent, tabular, foliated and fan-shaped crystals in emerald green to blue- green color.

Special Features

Chalkophyllit has a weak pleochroism, which manifests itself in the light passage to nw in blue-green color change and after nε in loss of color to near colorless.

Etymology and history

The mineral was named after the ancient Greek words χαλκός ( = copper) and φύλλου ( = leaf, leafy ). The term thus aims firstly to the copper and the foliated to scaly structure, belonging to the mica group minerals contained in the chemical composition.

Classification

In the old ( 8th edition ) and new classification of minerals according to Strunz ( 9th edition ) of the Chalkophyllit one of the hydrous phosphates with foreign or other anions. In the new Strunz'schen systematics and will be further divided, so that here the Chalkophyllit In the subsection " (phosphates, with additional anions, with H2O) With only medium-sized cations, (OH, etc.): RO 4 > 3:1 " to is found.

The ordered according to the crystal structure, classification of minerals according to Dana sorted the Chalkophyllit in the department of " Compound Phosphates, etc. ( Hydrated Compound With anion hydroxyl or halogen) " (translated: phosphate compounds and similar compounds containing water with hydroxide ion or halogens as anions )

Education and Locations

Chalkophyllit forms as a typical secondary mineral by oxidation to arsenic deposits ( mainly of arsenopyrite ), but can also by hydrothermal processes in reservoirs with many metals occur. Accompanying minerals include azurite, Brochantite, chrysocolla, cuprite, Cyanotrichite, malachite, Spangolith.

Locations include Neuquén in Argentina; the provinces of Limburg, Luxembourg and Namur in Belgium; La Paz in Bolivia; the regions of Antofagasta, Atacama and Libertador General Bernardo O'Higgins in Chile; different regions in Germany and France; Attica in Greece; England and Wales in the United Kingdom; several regions in Italy; Honshu in Japan; Souss- Massa- Daraâ in Morocco; Oshikoto Namibia; the North Island of New Zealand; several regions in Austria; the districts of Castelo Branco and Viseu in Portugal; the Ural Mountains in Russia; the cantons of Glarus and Valais in Switzerland; Banská Bystrica ( Okres ) and Košice in Slovakia; Valencia in Spain; Gauteng in South Africa; Bohemia and Moravia in the Czech Republic; Heves county in Hungary; and various regions in the United States.

Crystal structure

Chalkophyllit crystallizes in the trigonal crystal system in the space group ( trigonal- rhombohedral ) with the lattice parameters a = 10.76 Å and c = 28.68 Å and 3 formula units per unit cell.