Pääkkönenite

• IMA1980 -063

Pääkkönenit is a very rarely occurring mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the monoclinic crystal system with the chemical composition Sb2AsS2 is therefore an antimony - arsenic - sulfide.

Pääkkönenit is opaque in any form and develops rarely well formed crystals to about 0.4 millimeter in size. He usually can be found in the form of irregular grains or granular mineral aggregates from light to dark gray color and metallic luster. His stroke color is also gray with a brownish tinge.

With a Mohs hardness of about 2 Pääkkönenit belongs to the soft minerals, which can be similar to the reference mineral gypsum even scratch with your fingernail.

Etymology and history

Was first discovered Pääkkönenit in the arsenic -antimony deposit Kalliosalo in Seinäjoki in western Finland and described in 1981 by Yu. S. Borodaev, NN Mozgova, NA Ozerova, NS Bortnikov, P. and V. Oivanen Iletuinen. They named the mineral after the Finnish geologists Viekko Pääkkönen (1907-1980), to honor his contributions to the study of ore deposits in the type region.

Classification

Already in the outdated, but partly still in use 8th edition of the mineral classification by Strunz was one of Pääkkönenit to the mineral class of " sulfides and sulfosalts " and then to the Department of " sulfides with the molar ratio of metal: S, Se, Te <1: 1" where he led the unnamed group II/D.08 formed together with Antimonselit, bismuthinite, Guanajuatit, Metastibnite, Ottemannit and stibnite.

The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the Pääkkönenit other hand, in the department of " metal sulfides with M: S = 3: 4 and 2: 3". This is further subdivided by the exact molar ratio, so that the mineral according to its composition in the subsection "M: S = 2: 3 " can be found, where it forms the unnamed group 2.DB.05b the only member.

The mainly common in English-speaking classification of minerals according to Dana assigns the Pääkkönenit into the class of " sulfides and sulfosalts " and there in the department of " sulfide minerals ." Here he is the only member of the unnamed group 02:11:05 within the subdivision " sulfides - with the composition AmBnXp, with (m n) - including selenides and tellurides: p = 2: 3" to find.

Education and Locations

Pääkkönenit forms in hydrothermal ore deposits, where it is usually found in paragenesis with other arsenic -and antimony- bearing minerals such as arsenopyrite, among other things, Löllingite, Stibarsen, stibnite and Vaughanit. In addition, however pure antimony and arsenic, quartz, realgar, siderite and sphalerite occur as accompanying minerals.

So far, for Pääkkönenit only 10 localities known, its type locality Kalliosalo currently the only locality in Finland is in Seinäjoki.

Other previously known localities are the " Golden Giant Mine" at Marathon in the Canadian province of Ontario, a Kermesit - locality ( unnamed antimony mine ) at Dafeng near Shanglin in China, Pribram in the Czech region of Bohemia, the " Matra - mine " in French community Moïta (Haute -Corse), the " Plaka mines " in Lavrio in the Greek region of Attica and the " Cryo- Genie Mine" at Warner Springs in San Diego County ( California ) in the United States of America (USA).

Crystal structure

Pääkkönenit crystallizes in the monoclinic space group C2 / m ( Raumgruppen-Nr. 12) with the lattice parameters a = 10.75 Å; b = 3.96 Å; c = 12.49 Å and β = 115.2 °, and four formula units per unit cell.