Zellerit

from Wikipedia, the free encyclopedia
Zellerit
Zellerite 1.jpg
Light yellow, needle-like Zellerite in spherical aggregates with green tablets of Schröckingerite from White Canyon No. 1 mine (Cameo Mine), San Juan County (Utah) , USA (field of view 6 mm)
General and classification
other names

IMA 1965-031

chemical formula
  • Ca [UO 2 (CO 3 ) 2 (H 2 O) 2 ] • 3H 2 O
  • Ca [UO 2 | (CO 3 ) 2 ] • 5H 2 O
Mineral class
(and possibly department)
Carbonates and nitrates
System no. to Strunz
and to Dana
5.EC.10 ( 8th edition : V / F.02)
03/15/01/01
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol Orthorhombic-dipyramidal 2 / m 2 / m 2 / m or -pyramidal mm 2
Space group Pmmm or Pmn 21
Lattice parameters a  = 11.220 (15)  Å ; b  = 19.252 (16) Å; c  = 4.933 (16) Å
Formula units Z  = 4
Physical Properties
Mohs hardness 2
Density (g / cm 3 ) measured: 3.25 (1); calculated: 3.242
Cleavage no
colour light yellow, whitish yellow to lemon yellow
Line color White
transparency transparent to translucent
shine frosted
radioactivity very strong
Crystal optics
Refractive indices n α  = 1.536
n β  = 1.559
n γ  = 1.697
Birefringence δ = 0.161
Optical character biaxial positive
Axis angle 2V = measured: 30 to 45 °; calculated: 48 °
Pleochroism X = Y = colorless; Z = light yellow; Orientation: Z = c
Other properties
Chemical behavior soluble in acids

Zellerite is a very rare mineral from the mineral class of "carbonates and nitrates" (formerly "carbonates, nitrates and borates"). It crystallizes in the orthorhombic crystal system with the chemical composition Ca [UO 2 (CO 3 ) 2 (H 2 O) 2 ] · 3H 2 O and is thus a water-containing calcium - uranyl - carbonate .

Zellerit develops hair-fine fibers up to two millimeters in length and matt surfaces, which are usually connected to form spherical mineral aggregates or appear in the form of crusty coatings. The crystal fibers are transparent and light yellow to lemon yellow in color.

Zellerite shows green fluorescence in places under short and long-wave UV light .

Etymology and history

Zellerite was first discovered in July 1955 by geologist Howard D. Zeller (* 1922) in the Lucky MC Mine (Lucky Mac) in the Gas Hills District of Fremont County (Wyoming) in the USA and described in 1966 by RG Coleman, DR Ross and R. Meyrowitz, who named the mineral after its discoverer.

Type material of the mineral is stored in the National Museum of Natural History in Washington, DC under catalog number 112827.

classification

In the meantime outdated, but still in use 8th edition of the mineral classification by Strunz of Zellerit belonged to common mineral class of "carbonates, nitrates and borates " and then to the Department of uranyl carbonate , where he together with Andersonit , liebigite , Bayleyit , Čejkait , Fontanit , Grimselit , Metazellerit , and Swartzit formed the unnamed group V / F.02 .

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), assigns Zellerite to the newly defined class of “carbonates and nitrates”, but also to the “uranyl carbonates” class there. However, this is further subdivided according to the molar ratio of the uranyl to the carbonate complex, so that the mineral can be found in the sub-section "UO 2  : CO 3  = 1: 3" according to its composition , where it only belongs to the unnamed group 5 together with metazellerite .EC.10 forms.

The systematics of the systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Zellerite to the common class of "carbonates, nitrates and borates" like the outdated Strunz system. There the Zellerite is, however, in the section of "Hydrogenous carbonates" and the subdivision of "Hydrous carbonates" with the general composition A + m B 2+ n (XO 3 ) p • x (H 2 O), the ratio (m + n ): p = 1: 1 and with U, Th, Zr, Y “, where it also forms the unnamed group 03/15/01 together with metazellerite .

Crystal structure

Zellerite crystallizes orthorhombically in the space group Pmmm (space group no. 47) or Pmn 2 1 (no. 31) with the lattice parameters a  = 11.220 (15)  Å ; b  = 19.252 (16) Å; c  = 4.933 (16) Å and 4 formula units per unit cell . Template: room group / 47Template: room group / 31

properties

The mineral is very radioactive due to its uranium content of up to 45.76% . Taking into account the proportions of the radioactive elements in the idealized empirical formula and the subsequent decays of the natural decay series , a specific activity of about 81.9 k Bq / g is specified for the mineral (for comparison: natural potassium 0.0312 kBq / g). The quoted value can vary significantly depending on the mineral content and composition of the levels; selective enrichment or depletion of the radioactive decay products is also possible and changes the activity.

Education and Locations

Zellerite is formed as a secondary mineral through the weathering of uraninite and coffinite at pH values greater than 7 in the presence of oxidizing pyrite . As Begleitminerale occur next uraninite more uranium minerals such as, among others Autunit , schröckingerite , Uranophan and Schoepit , but also different iron sulfides and oxides such. B. Limonite , the calcium sulfate gypsum and the water-containing silicon oxide opal .

As a very rare mineral formation, Zellerite could only be detected in a few samples at a little more than 10 sites (as of 2014).

In addition to its Lucky MC Mine type locality , the mineral occurred in the United States in the Pumpkin Buttes District ( Campbell County ) in Wyoming, the White Canyon No. 1 mine (Cameo Mine) in the White Canyon District in San Juan County in Utah and in the Alta Mine in the vicinity of Smith Lake and Ambrosia Lake in the Grants District of McKinley County in New Mexico.

Other previously known sites are the Elias Mine near Jáchymov (German Sankt Joachimsthal ) and Předbořice (Central Bohemia ) and the Bukov Mine in the Rožná uranium deposit ( Kraj Vysočina , Moravia) in the Czech Republic, Mas d'Alary near Lodève in the French region of Languedoc- Roussillon, the uranium barite deposit "Belorechensk" on the Balaja river near the village of Kamennomostski (not, as is often assumed, Beloretschensk ) in Russia and Banská Štiavnica (German Schemnitz or Schebnitz ) in Slovakia.

There are also sites in the Hatrurim formation in the Israeli Negev desert .

Precautions

Due to the high level of radioactivity , mineral samples from Zellerit should only be kept in dust- and radiation-proof containers, but especially never in living rooms, bedrooms or workrooms. Absorption into the body (incorporation, ingestion ) should also be prevented in any case and, for safety, direct body contact should be avoided and respiratory protection mask and gloves should be worn when handling the mineral .

See also

literature

  • RG Coleman, DR Ross, R. Meyrowitz: Zellerite and metazellerite, new uranyl carbonates. In: American Mineralogist. Volume 51 (1966), pp. 1567–1578 ( PDF 696.4 kB )
  • Michael Fleischer : New mineral names.Zellerite In: American Mineralogist Volume 49 (1964), pp. 439–448 ( PDF 666 kB )

Web links

Commons : Zellerite  - collection of images, videos and audio files

Individual evidence

  1. a b c d e Ray L. Frost, Marilla J. Dickfos, Jiří Čejka: Raman spectroscopic study of the uranyl carbonate mineral zellerite. In: Journal of Raman Spectroscopy. Volume 39 (2008), pp. 582–586 doi : 10.1002 / jrs.1879 ( PDF 238.1 kB )
  2. ^ Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  320 .
  3. a b c Stefan Weiss: The large Lapis mineral directory. All minerals from A - Z and their properties . 5th completely revised and supplemented edition. Weise, Munich 2008, ISBN 978-3-921656-70-9 .
  4. a b c d e f g Zellerite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 68 kB )
  5. a b c Mindat - Zellerite
  6. a b RG Coleman, DR Ross, R. Meyrowitz: Zellerite and metazellerite, new uranyl carbonates. In: American Mineralogist. Volume 51 (1966), pp. 1567–1578 ( PDF 696.4 kB )
  7. a b Webmineral - Zellerite
  8. Mindat - Number of localities for Zellerite
  9. minerals Atlas: Belorechensk (Belorecensk; Belorechensk) , location description and Mineral list
  10. Find location list for Zellerite at the Mineralienatlas and at Mindat