Raspit
| Raspit | |
|---|---|
 |
|
| General and classification | |
| chemical formula | α-PbWO 4 |
|
Mineral class (and possibly department) |
Oxides and hydroxides (including V [5,6] vanadates, arsenides, antimonides, bismuthides, suldides, selenides, tellurides, iodides) |
|
System no. to Strunz and to Dana |
4.DG.20 ( 8th edition : IV / D.24) 48.01.04.01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Room group (no.) | P 2 1 / a (No. 14) |
| Lattice parameters |
a = 13.56 Å ; b = 4.98 Å; c = 5.56 Å β = 107.6 ° |
| Formula units | Z = 4 |
| Twinning | according to {100} and { 1 02} |
| Physical Properties | |
| Mohs hardness | 2.5 to 3 |
| Density (g / cm 3 ) | measured: 8.46; calculated: 8.45 |
| Cleavage | completely after {100} |
| colour | light yellow to yellowish brown, gray |
| Line color | yellowish white |
| transparency | translucent |
| shine | Diamond luster |
| Crystal optics | |
| Refractive indices |
n α = 2.270 n β = 2.270 n γ = 2.300 |
| Birefringence | δ = 0.030 |
| Optical character | biaxial positive |
| Axis angle | 2V = measured: ≈ 0 ° |
Raspit is a rarely occurring mineral with the chemical composition α-PbWO 4 . It crystallizes in the monoclinic crystal system and would only its chemical formula for the more lead - tungstates associate. Due to its crystal structure , however, it belongs to the mineral class of " oxides and hydroxides " in Strunz's mineral systematics with the molar ratio of metal: oxygen = 1: 2 (and comparable).
Raspit is translucent and develops only small, tabular, longitudinally striped crystals and twins a few millimeters in length from light yellow to yellowish brown or gray in color with yellowish white streak color . The crystal surfaces show a diamond-like sheen .
Special properties
At a temperature of over 410 ° C, Raspit changes into Stolzite .
Etymology and history
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The mineral was first discovered in 1896 on two samples from the collection of the Natural History Museum Vienna (formerly kk Naturhistorisches Hof-Museum ), which Baron Heinrich Foullon von Norbeeck (1850-1896) received in Broken Hill (Australia). Baron von Norbeeck suspected a new mineral on the samples, for which he suggested the name Raspit, after the German emigrant Charles Rasp (1846-1907). He had discovered the deposits in and around Broken Hill and recognized their economic importance.
The mineral was analyzed and described in 1897 by Karl Hlawatsch (also Carl Hlawatsch , 1870–1947), who adopted Baron von Norbeeck's proposed name.
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the Raspit belonged to the mineral class of "oxides and hydroxides" and there to the department of "oxides with the molar ratio metal: oxygen = 1: 2 (MO 2 and related compounds) ", Where he together with fergusonite (Ce) , fergusonite (Nd) , fergusonite (Y) , fergusonite beta (Ce) , fergusonite beta (Nd) , fergusonite beta (Y) , formanite (Y) and Iwashiroit- (Y) the "Fergusonite series" with the system no. IV / D.24 .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also classifies the Raspit in the department of "Oxides with the molar ratio of metal: oxygen = 1: 2 and comparable". However, this is further subdivided according to the relative size of the cations involved and the crystal structure, so that the mineral is classified in the sub-section “With large (± medium-sized) cations; Chains of edge-linked octahedra “can be found, where it is the only member of the unnamed group 4.DG.20 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Raspit to the class of "phosphates, arsenates and vanadates" and there to the department of "molybdates and tungstates". Here he is the only member of the unnamed group 48.01.04 within the sub-section “ Anhydrous molybdates and tungstates with A XO 4 ”.
Modifications and varieties
The compound PbWO 4 is dimorphic and occurs naturally in addition to the monoclinic crystallizing raspite as a tetragonal crystallizing prolzite .
Education and Locations
Raspite formed secondarily in the oxidation zone of tungsten-bearing hydrothermal - deposits . As accompanying minerals may include Alumotungstit and Ferritungstit ( varieties of Hydrokenoelsmoreit ) Cuprotungstit , Stolzit and Yttrotungstit .
As a rare mineral formation, Raspit could only be detected in a few places, whereby so far (as of 2013) around 20 sites are known. In addition to its Broken Hill type locality , the mineral could only be found in Australia in the "Cordillera Mine" near Kangaloolah (Georgiana County, New South Wales ).
The only known site in Germany so far is the Clara mine near Oberwolfach.
Other previously known sites include Sumidouro in the Brazilian state of Minas Gerais ; the uranium deposit in the Otish Mountains near James Bay (Baie-James) in Canada; an unnamed iron-germanium deposit near Nanyue (Hengyang) in China; Échassières ( Département Allier ), Meymac (Département Corrèze) and Compolibat ( Département Aveyron ) in France; Gyojayama near Kameoka on the Japanese island of Honshū; the "San Antonio Mine" at Santa Eulalia (Chihuahua) and a tin vein at Cerro de Estaño east of Guanajuato in Mexico; the Erongo Mountains in Namibia; Estorãos (Ponte de Lima) in Portugal; Gifurwe in the northern province of Rwanda and the Carr Canyon near Hartford and Tombstone in Cochise County in the US state of Arizona.
Crystal structure
Raspit crystallizes monoclinically in the space group P 2 1 / a (space group no. 14) with the lattice parameters a = 13.56 Å ; b = 4.98 Å; c = 5.56 Å and β = 107.6 ° and 4 formula units per unit cell .
The crystal structure of Raspit consists of edge-sharing [WO 6 ] octahedra , which form zigzag chains parallel to the b-axis and are connected via lead atoms.
See also
literature
- C. Hlawatsch: About the Stolzite and a new mineral "Raspit" from Brokenhill. In: Annals of the Imperial and Royal Natural History Court Museum. Volume 12 (1897), pp. 33-41 ( rruff.info PDF; 696.8 kB; Raspit from p. 7).
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 540 (first edition: 1891).
- Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 689 .
Web links
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- Mineral Atlas: Raspit (Wiki)
- Database-of-Raman-spectroscopy - Raspite.
- American-Mineralogist-Crystal-Structure-Database - Raspite.
Individual evidence
- ↑ a b c d e 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. 221 .
- ↑ Webmineral - Raspite.
- ↑ a b c d e f Raspite. In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America. 2001 ( handbookofmineralogy.org PDF; 64.6 kB).
- ↑ a b Mindat - Raspite.
- ^ Vera MF Hammer, Franz Pertlik: Karl Hlawatsch (* November 25, 1870 Vienna, † December 17, 1947 Vienna). In: Annals of the Natural History Museum in Vienna. Series A for Mineralogy and Petrography, Geology and Paleontology, Anthropology and Prehistory. Volume 107, 2005, pp. 1-22.
- ↑ Mindat - Number of localities for Raspit.
- ^ E. Wittich: About the occurrence of Raspit in North America. In: Journal of the German Geological Society. Volume 63, 1911, pp. 425–427 ( short version on schweizbart.de )
- ↑ Find location list for Raspite in the Mineralienatlas and in Mindat .