Walpurgin
| Walpurgin | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula |
|
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.EA.05 ( 8th edition : VII / E.10) 40.05.09.01 |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triclinic pinacoidal; 1 |
| Space group | P 1 (No. 2) |
| Lattice parameters |
a = 7.14 Å ; b = 10.43 Å; c = 5.49 Å α = 101.5 °; β = 110.8 °; γ = 88.2 ° |
| Formula units | Z = 1 |
| Frequent crystal faces | {010}, {110}, {1 1 0}, { 1 1 1} |
| Twinning | mostly after {010} |
| Physical Properties | |
| Mohs hardness | 3.5 |
| Density (g / cm 3 ) | calculated: 6.59 |
| Cleavage | completely after {010} |
| colour | bitter orange to waxy yellow; Straw yellow to honey yellow, light yellow to colorless in transmitted light |
| Line color | light brownish yellow |
| transparency | transparent to translucent |
| shine | Greasy gloss to diamond gloss |
| radioactivity | highly radioactive |
| Crystal optics | |
| Refractive indices |
n α = 1.871 to 1.910 n β = 1.975 to 2.000 n γ = 2.005 to 2.060 |
| Birefringence | δ = 0.134 to 0.150 |
| Optical character | biaxial negative |
| Axis angle | 2V = 50 to 60 ° (measured); 54 to 74 ° (calculated) |
| Pleochroism | X = colorless; Y = Z = very pale greenish yellow |
Walpurgin is a rarely occurring mineral from the mineral class of " phosphates , arsenates and vanadates " with the chemical composition (BiO) 4 [UO 2 | (AsO 4 ) 2 ] · 2H 2 O and thus chemically a water-containing bismuth - uranyl arsenate (or uranyl arsenate ).
Walpurgin crystallizes in the triclinic crystal system and develops mostly transparent to translucent crystals up to about 6 mm in length with a tabular to strip-shaped habit that are stretched along the c-axis. However, it also occurs in the form of radial mineral aggregates . The color of the mineral varies between different shades of yellow, which are described as bitter orange , wax yellow, straw yellow to honey yellow. Walpurgin appears light yellow to colorless in transmitted light. However, it leaves a light brownish-yellow line on the marking board . The surfaces of the crystals have a fat to diamond-like sheen .
With a Mohs hardness of 3.5, Walpurgin lies between the reference minerals calcite (hardness 3) and fluorite (hardness 4), so it is easy to scratch with a knife .
Etymology and history
Walpurgin was discovered on an ore level that the mountain manager Otto Richard Tröger made Professor Dr. Albin Weisbach submitted for assessment. The point of discovery of this ore stage was the 26- Lachter site on the Walpurgis flat in the mine field of the “Weißer Hirsch” mine in the Erzgebirge mountain town of Neustädtel . After an analysis of the ore samples by Dr. Clemens Winkler described the minerals found to Weisbach. These included the new minerals Trögerite , Zeunerite , Uranospinite and Uranosphärite as well as Walpurgin.
classification
Already in the outdated 8th edition of the mineral systematics according to Strunz , the Walpurgin belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates, arsenates and vanadates with foreign anions ", where together with arsenobismit it belonged to the system -No. VII / D.18 and the other Member Phosphowalpurgin formed.
In the Lapis mineral directory according to Stefan Weiß, which, out of consideration for private collectors and institutional collections, is still based on this old form of Karl Hugo Strunz's system , the mineral was given the system and mineral number. VII / E.10-20 . In the "Lapis system" this corresponds to the section "Uranyl phosphates / arsenates and uranyl vanadates with [UO 2 ] 2+ - [PO 4 ] [AsO 4 ] 3- and [UO 2 ] 2+ - [V 2 O 8 ] 6- , with isotypic vanadates (Sincosit-R.) "where Walpurgin together with Asselbornit , Orthowalpurgin , Phosphowalpurgin and Sreinit forms a separate, but unnamed group (as of 2018).
The 9th edition of Strunz's mineral systematics , valid since 2001 and updated by the International Mineralogical Association (IMA) until 2009, also assigns Walpurgin to the class of "phosphates, arsenates and vanadates" and there in the department of "uranyl phosphates and arsenates". However, this is further subdivided according to the molar ratio of the uranyl complex (UO 2 ) to the phosphate, arsenate or vanadate complex (RO 4 ), so that the mineral according to its composition in the sub-section "UO 2 : RO 4 = 1: 2" can be found where, together with Orthowalpurgin and Phosphowalpurgin, the "Walpurgin group" named after him with the system no. 8.EA.05 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Walpurgin to the class of "phosphates, arsenates and vanadates" and there in the department of "water-containing phosphates etc.". Here he is also named after the " Walpurging Group " with the system no. 40.05.09 and the other members Orthowalpurgin and Phosphowalpurgin can be found in the sub-section "Water-containing phosphates etc., with different formulas".
Crystal structure
Walpurgin crystallizes triclinically in the space group P 1 (space group no. 2) with the lattice parameters a = 7.14 Å ; b = 10.43 Å; c = 5.49 Å; α = 101.5 °; β = 110.8 ° and γ = 88.2 ° and one formula unit per unit cell .
properties
The mineral is classified as very radioactive due to its uranium content of up to 16% and has a specific activity of around 28.7 k Bq / g (for comparison: natural potassium 31.2 Bq / g).
Modifications and varieties
The compound (BiO) 4 [UO 2 | (AsO 4 ) 2 ] · 2H 2 O is dimorphic and occurs naturally in addition to the triclinic crystallizing walpurgine as orthorhombic crystallizing orthowalpurgite.
Education and Locations
(size: 1 cm × 1 cm)
Walpurgin formed secondarily in the oxidation zone of bismuth -, uranium - and arsenic , hydrothermal deposits . Accompanying minerals include torbernite , trögerite , uranosphere , uranospinite and zeunerite .
As a rare mineral formation, Walpurgin has so far only been proven at a few sites, of which around 30 are known. In addition to its type locality "Walpurgis-Flachen" in the "Weißer Hirsch" shaft, the mineral appeared in Germany in many other shafts in Neustädtel, in the area around Schneeberg and in the Ore Mountains in Saxony and in several places in the Black Forest in Baden-Württemberg.
Other locations include Namibia , Portugal , the Czech Republic , the United Kingdom and the United States .
Precautions
Due to the toxicity and the high level of radioactivity of the mineral, samples should only be stored in dust- and radiation-tight containers, but especially never in living rooms, bedrooms or workrooms. Absorption into the body ( incorporation ) should also be prevented in any case and direct body contact should be avoided to be on the safe side and face masks and gloves should be worn when handling the mineral.
See also
literature
- Albin Weisbach: Preliminary notification . In: G. Leonhard, HB Geinitz (Hrsg.): New yearbook for mineralogy, geology and palaontology . Verlag von Friedrich Schweizerbart, Stuttgart 1871, II. B, p. 869-870 ( rruff.info [PDF; 142 kB ; accessed on March 15, 2020] excerpt).
- Albin Weisbach: New uranium ores from Neustädtel near Schneeberg . In: G. Leonhard, HB Geinitz (Hrsg.): New yearbook for mineralogy, geology and palaontology . E. Schweizerbart'sche Verlagshandlung, Stuttgart 1873, p. 314–317 ( rruff.info [PDF; 329 kB ; accessed on March 15, 2020] excerpt).
- Albin Weisbach: Mineralogical messages . In: CG Gottschalk (Hrsg.): Yearbook for mining and metallurgy in the Kingdom of Saxony to the year 1877 . Craz & Gerlach, Freiberg 1878, treatises from the field of mining and metallurgy, p. 42–45 ( rruff.info [PDF; 509 kB ; accessed on March 15, 2020] excerpt).
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 656 (first edition: 1891).
Web links
- Mineral Atlas: Walpurgin (Wiki)
- Visitor mine Fundgrube Weißer Hirsch. Sächsischer Bergbauverein Weißer Hirsch Schneeberg eV, November 19, 2018, accessed on March 15, 2020 .
Individual evidence
- ↑ Waltherite (of Vogl). In: mindat.org. Hudson Institute of Mineralogy, accessed August 30, 2019 .
- ↑ Malcolm Back, William D. Birch, Michel Blondieau and others: The New IMA List of Minerals - A Work in Progress - Updated: March 2020. (PDF 1729 kB) In: cnmnc.main.jp. IMA / CNMNC, Marco Pasero, March 2020, accessed March 15, 2020 .
- ↑ 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. 522 (English).
- ^ A b David Barthelmy: Walpurgite Mineral Data. In: webmineral.com. Retrieved May 23, 2019 .
- ↑ a b c d e f g Walpurgite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 67 kB ; accessed on May 23, 2019]).
- ↑ Albin Weisbach: preliminary communication (1871)
- ↑ a b c d e f Walpurgite. In: mindat.org. Hudson Institute of Mineralogy, accessed May 23, 2019 .
- ↑ Yearbook for the mining and metallurgical industry in the Kingdom of Saxony to the year 1873. In: digital.ub.tu-freiberg.de. Technische Universität Bergakademie Freiberg, pp. 135 ff , accessed on May 23, 2019 .
- ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
- ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1816 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed March 15, 2020 .
- ↑ Mindat - Number of localities for Walpurgin (Walpurgite)