Schoepite

Schoepit is a rarely occurring mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the orthorhombic crystal system with the chemical composition [( UO2) 4 | O | (OH ) 6] · 6H2O and usually develops clear and diamond- bright crystals with tabular, but also short prismatic habit to { 001 } and lemon yellow, sulfur- yellow or brownish -yellow color with light yellow stroke color. Rarely, microcrystalline mineral aggregates.

Special Features

The mineral is classified as very highly radioactive due to its uranium content of up to 72.9 % and has a specific activity of about 130.5 kBq / g (compared to natural potassium 0.0312 Bq / g).

Under UV light, show some Schoepite a green fluorescence.

Etymology and history

Was first discovered in 1922 in the Schoepit " Shinkolobwe Mine" ( Kasolo mine ) in what is now the Democratic Republic of Congo ( Zaire) belonging Katanga province and described in 1923 by Thomas Leonard Walker, who named it after the Belgian geographer and mineralogist Alfred Schoep.

The type of mineral is located in the Royal Ontario Museum in Toronto, Canada.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Schoepit belonged to the mineral class of " oxides and hydroxides " and then to the Department of " uranyl hydroxides and hydrates ", where he, along with Ianthinit, Metaschoepit, Metastudtit Paraschoepit and studtite 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 Schoepit also included in the category of " oxides and hydroxides " and there in the department of " Uranyl Hydroxide ." This division, however, is further subdivided according to the possible presence of other cations, so that the mineral is found according to its composition in the subdivision " without additional cations " where it only forms together with Metaschoepit and Paraschoepit the unnamed group 4.GA.05.

The classification of minerals according to Dana assigns the Schoepit in the class of " oxides and hydroxides ", but there in the department of " uranium and thorium oxides " one. He is also, along with Metaschoepit and Paraschoepit in the unnamed group 05:02:01 within the subdivision " uranium and thorium -containing oxides with a cation charge of 6 ( AO3 ), and hydrated " to find.

Education and Locations

Schoepit forms as a rare alteration product of uraninite by hydrothermal processes in uranium deposits and is accordingly mostly in paragenesis with this, but also with Arsenuranylit, Becquerelit, Billietit, Curit, Fourmarierit, Ianthinit, Metazeunerit, Nováčekit, Paraschoepit, Rutherfordin, Soddyit, uranophane to find Uranospinite and Vanden Dries log.

There is often Schoepit as a direct product of the transformation of unstable air Ianthinits. Complete pseudomorphs after Ianthinit are also called " Epi - Ianthinit ". Schoepit itself turns slowly on air to Metaschoepit ( ( UO3 ) · nH2O n ≈ 2 ) by first escaping the crystal water between the layers of the crystal lattice, so that it finally comes to a breakdown of the lattice and a subsequent rearrangement to a more stable structure. Usually show the crystals of Schoepits adhesions of both minerals. In this context, it is discussed that Metaschoepit still continue to " dehydrated Schoepit " ((( UO3 ) · nH2O n ≈ 0.75 to 1 ) ) converts.

A rare mineral formation Schoepit could be detected only in a few localities, where so far (as of 2013) are about 90 localities known as. Apart from its type locality " Shinkolobwe Mine" came the mineral in the Democratic Republic of Congo still in the " Musonoi Mine" at Kolwezi and uranium mining east of Kamoto evident.

In Germany Schoepit Among other findings in the " Kirchheimerstraße tunnel " in Baden- Baden- waste stream, on the now no longer accessible stockpiles of uranium deposit Krunkelbachtal near Menzenschwand and in the Clara mine in Oberwolfach in Baden- Württemberg; in " John Shaft" at Wölsendorf in Bavaria; on Bühlskopf at Ellweiler in Rhineland-Palatinate and at Schneeberg in Saxony's Erzgebirge.

The only known locality in Switzerland is a gap at the Albignagletscher in the canton of Grisons.

Other localities lie among others in Argentina, Australia, China, France, Gabon, Italy, Japan, Canada, Mexico, New Zealand, Norway, Russia, Tajikistan, the Czech Republic, Hungary, the United Kingdom ( England, Scotland ) as well as in several states of the USA (Arizona, Colorado, Maine, New Hampshire, Utah).

Crystal structure

Schoepit crystallizes in the orthorhombic space group P21ca ( Raumgruppen-Nr. 29) with the lattice parameters a = 14.34 Å; b = 16.81 Å and c = 14.73 &bsp; Å and eight formula units per unit cell.

The crystal structure of Schoepits is topologically identical to the Fourmarierits. The uranium atom has a pentagonal- bipyramidal geometry, with the uranyl oxygen atoms are located on the axis and the equatorial plane forming layers of edge-and corner-sharing oxygen atoms.