Sabugalit
| Sabugalit | |
|---|---|
 |
|
| General and classification | |
| chemical formula | (AlH) 0.5 [UO 2 | PO 4 ] 2 • 8H 2 O |
|
Mineral class (and possibly department) |
Phosphates , arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.EB.55 ( 8th edition : VII / E.01) 40.02a.24.01 |
| Crystallographic Data | |
| Crystal system | monoclinic - pseudotetragonal |
| Crystal class ; symbol | 2 / m |
| Room group (no.) | C 2 / m (No. 12) |
| Lattice parameters |
a = 19.43 Å ; b = 9.84 Å; c = 9.85 Å β = 96.2 ° |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 2.5 |
| Density (g / cm 3 ) | 3.2 |
| Cleavage | completely [001] |
| colour | light yellow to lemon yellow |
| Line color | yellow white |
| transparency | transparent to translucent |
| shine | Glass gloss |
| radioactivity | highly radioactive |
| Crystal optics | |
| Refractive indices |
n α = 1.564 to 1.565 n β = 1.581 to 1.583 n γ = 1.582 to 1.584 |
| Other properties | |
| Special features | Luminescence under UV radiation |
Sabugalite or aluminum autunite is a rarely occurring mineral belonging to the mineral class of phosphates , arsenates and vanadates . It crystallizes in the monoclinic crystal system with the chemical composition (AlH) 0.5 [UO 2 | PO 4 ] 2 · 8H 2 O and forms yellow, thin, square or elongated crooked crystals of up to one millimeter in size. The mineral is often found in adhesions in the form of thick crusts.
Etymology and history
Sabugalite was first described in 1951 by Clifford Frondel, who made some of it by the Portuguese mineralogist A. d'O. Bello investigated uranium minerals acquired in 1932. The Mina da Quarta Seira near the city of Sabugal in Portugal , after which Sabugalit is named, is considered to be the type locality of the new mineral .
There are three type minerals at the Natural History Museum in London , Harvard University in Cambridge , Massachusetts, and the National Museum of Natural History , Washington, DC
classification
In the Strunz system , sabugalite is counted among the uranyl phosphates and arsenates. After the 8th edition it forms the autunite group together with Autunit , Fritzscheit , Heinrichit , Kahlerit , Metanatroautunit , Novácekit , Saléeit , Torbernit , Trögerit , Uranocircit , Uranospinit and Zeunerit . In the 9th Edition the uranyl phosphates and arsenates can be according to the ratio of uranyl to phosphate / arsenate ions divided here it forms with Arsenuranospathit and Uranospathit a subset of uranyl phosphates with a ratio of UO 2 to P / AsO 4 of 1: 1.
In the Dana system , it forms a separate subgroup of the water-containing phosphates etc. with the general structure A 2+ (B 2+ ) 2 (XO 4 ) · x (H 2 O), which contain (UO 2 ) 2+ .
Crystal structure
Sabugalite crystallizes in the monoclinic crystal system in the space group C 2 / m (space group no .: 12) with the lattice parameters a = 19.43 Å ; b = 9.84 Å; c = 9.85 Å and β = 96.2 ° as well as 4 formula units per unit cell .
properties
Sabugalite fluoresces under UV radiation . When heated, the mineral gives off the water of crystallization in three stages , above 220 ° C there is no more water in the sabugalite. It can be obtained artificially from aqueous solutions containing uranyl and aluminum compounds and phosphoric acid . It crystallizes from this after a few weeks.
Due to a uranium content of up to 53.6% is Sabugalit as highly radioactive classified and has a specific activity of about 96 k Bq / g (compared to natural potassium 0.0312 kBq / g).
Education and Locations
Sabugalite forms as a secondary mineral in the oxidized zone of uranium veins. The type mineral from Sabugal crystallizes on a matrix of quartz and feldspar . Other mineral samples from this region form crusts on aged granite and other pegmatitic rocks . Other matrices are kaolinized feldspar and limonite . It is associated with Metaautunit , Saléeit and Phosphuranylit .
There are currently (as of 2010) about 80 sites for Sabugalite known. In addition to the type locality and other places in Portugal, Sabugalit can be found in the Haute-Vienne , Deux-Sèvres and other places in France , in Weißenstadt and Mähring in Germany , in Capoterra in Sardinia ( Italy ), in Don Benito in Spain , in Galiléia in Brazil as well as the US states Arizona , Colorado , Nebraska , Nevada , New Mexico and Utah .
Precautions
Due to the toxicity and the strong radioactivity of the mineral, mineral samples from Sabugalite 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
Individual evidence
- ↑ a b c d e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 523 .
- ↑ Sabugalit in: Anthony et al .: Handbook of Mineralogy , 1990, 1, 101.
- ^ A b Clifford Frondel: Studies of uranium minerals (VIII): Sabugalite, an aluminum-autunite. In: American Mineralogist . 1951, 36, p. 671. ( PDF, English, 603 kB )
- ^ New Dana Classification of Phosphate Minerals
- ↑ R. Vochten, J. PELSMAEKERS: Synthesis, Solubility, Electro Kinetic Properties and Refined Crystallographic Data of Sabugalite. In: Phys. Chem. Minerals. 1983, 9 pp. 23-29.
- ↑ Webmineral - Sabugalite
- ↑ Sabugalite at mindat.org (Eng.)
literature
- Sabugalit in: Anthony et al .: Handbook of Mineralogy , 1990, 1, 101 ( PDF, English, 67.3 kB ).
- Clifford Frondel: Studies of uranium minerals (VIII): Sabugalite, an aluminum-autunite. In: American Mineralogist . 1951, 36, p. 671. ( PDF, English, 603 kB )
- R. Vochen, J. Pelsmaekers: Synthesis, Solubility, Electrokinetic Properties and Refined Crystallographic Data of Sabugalite. In: Phys. Chem. Minerals. 1983, 9 pp. 23-29, doi : 10.1007 / BF00309466 .
