Halotrichite

Halotrichit, also known as mountain butter, iron alum, Federalaun or salt or hair salt, is a mineral from the mineral class of " sulfates ( and relatives ) ," which can be in different localities partly abundant, but overall not very common.

Halotrichit crystallizes in the monoclinic crystal system with the chemical composition Fe2 Al2 [ SO4 ] 4 • 22 H2O and usually develops fibrous aggregates and crusty coatings, more rarely, needle-shaped crystals of white to gray apple green color.

Special Features

Halotrichit is water soluble. For this reason, the crystals can dissolve at high humidity. The crystal water may be, similar to other sulfates can be discharged under a dry condition, wherein the mineral is divided.

Etymology and history

Named after the Latin word Halotrichit halotrichum for hair salt, originally from AltGr. ἅλς [ Háls ] "salt" and θριξ [ thrix ], genitive τρίχος [ tríchos ] " Hair ". First found and described the mineral in 1839 by Ernst Friedrich Glocker.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Halotrichit to the mineral class of " sulfates, selenates, tellurates, chromates, molybdates, tungstates " and then to the department which was part of " water -containing sulfates without foreign anions ", where he with Apjohnit, Bílinit, Dietrichit, Pickeringite, Redingtonit and Wupatkiit formed a distinct group.

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the Halotrichit in the class of " sulfates ( selenates, tellurates, chromates, molybdates and tungstates ) " and then in the Department of " Sulfate ( selenates, etc.) without additional anions, with H2O ". This division, however, is further divided according to the size of the cations involved, so that the mineral is "With only medium-sized cations " to find according to its composition in the subdivision where it is named as the " Halotrichitgruppe " with the system no. Forms 7.CB.85 and the other members Apjohnit, Bílinit, Caichengyunit, Dietrichit, Pickeringite, Redingtonit and Wupatkiit.

The mostly commonly used in English-speaking classification of minerals according to Dana assigns the Halotrichit in the class of " sulfates, chromates and molybdates " and there in the department of " water -containing acids and sulfates " one. Here it is also named the " Halotrichitgruppe (monoclinic with 22 H2O) " with the system no. Find 29/07/03 and the other members Apjohnit, Bilinit, Dietrichit, Pickeringite, Redingtonit and Wupatkiit within the sub-division of " water -containing acids and sulfates with A (B ) 2 ( XO4 ) 4 × x (H2O) ".

Education and Locations

Halotrichit normally forms secondarily by oxidation of pyrite. It is however also found in solfataras and thermal springs. Will be accompanied by various other Halotrichit sulfates.

Locations include Catamarca, Salta and San Juan in Argentina; in some regions of Australia; Departamento Oruro and Potosí Department in Bolivia; in Haskovo in Bulgaria; in many regions of Germany; Finland; at the Solfatara of Pozzuoli in Italy; Iran; Nova Scotia, Quebec and Yukon in Canada; Chile; People's Republic of China; Carinthia, Salzburg and Styria in Austria; as well as in many regions of Hungary and the USA.

Crystal structure

Halotrichit crystallizes in the monoclinic space group ( Raumgruppen-Nr. 14) with the lattice parameters a = 21.26 Å; b = 24.26 Å; c = 6.19 Å and 100.3 ° and β = 4 formula units per unit cell.