Andersonite
| Andersonite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Na 2 Ca [UO 2 | (CO 3 ) 3 ] • 6H 2 O |
|
Mineral class (and possibly department) |
Carbonates and nitrates (formerly carbonates, nitrates and borates) |
|
System no. to Strunz and to Dana |
5.ED.30 ( 8th edition : V / F.02) 02.15.05.01 |
| Crystallographic Data | |
| Crystal system | trigonal |
| Crystal class ; symbol | ditrigonal-scalenohedral; 3 2 / m |
| Space group | R 3 m (No. 166) |
| Lattice parameters | a = 18.009 Å ; c = 23.838 Å |
| Formula units | Z = 18 |
| Physical Properties | |
| Mohs hardness | 2.5 |
| Density (g / cm 3 ) | measured: 2.8; calculated: 2.86 |
| Cleavage | not defined |
| colour | yellow green, light green |
| Line color | light yellow |
| transparency | transparent to translucent |
| shine | Glass gloss |
| radioactivity | very strong |
| Crystal optics | |
| Refractive indices |
n ω = 1.520 n ε = 1.540 |
| Birefringence | δ = 0.020 |
| Optical character | uniaxial positive |
| Other properties | |
| Chemical behavior | water soluble |
| Special features | Fluorescence : light green with short-wave UV light and turquoise with long-wave UV light |
Andersonite is a rarely occurring mineral from the mineral class of "carbonates and nitrates" with the chemical composition Na 2 Ca [UO 2 | (CO 3 ) 3 ] · 6H 2 O and is therefore chemically a water-containing sodium - calcium - uranyl carbonate .
Andersonite crystallizes in the trigonal crystal system and rarely develops crystals and occurs more frequently in the form of greenish-yellow, crusty aggregates and coatings, especially on sandstone .
Etymology and history
Andersonite was first found in 1951 by geologist Charles A. Anderson (1902-1990) in the Hillside Mine near Baghdad in Yavapai County of the US state of Arizona together with the previously unknown uranyl carbonates Swartzite and Bayleyite . The mine was initially known for its gold, silver, lead and zinc content in the form of sulphidic minerals. The uranium minerals were only found at one point as a 0.3 mm thick layer on gypsum, about 12 m above the water table. The geological origin of the uranium was not known and subsequent mine work did not allow any further geological investigations. 3.8 mg of andersonite were available for the first analyzes, so that the further analyzes on synthetic material were verified. The mineral was eventually named after its discoverer.
The type material of the mineral is kept at the National Museum of Natural History (Catalog No. 106112-106115) in Washington, DC .
classification
In the outdated 8th edition of the mineral classification according to Strunz , the andersonite belonged to the common mineral class of "carbonates, nitrates and borates" and there to the department of "hydrous carbonates with foreign anions ", where together with bayleyite , Liebigite , metazellerite , rabbittite , rutherfordin , Schröckingerit , Sharpit , Studtit , Swartzit , Voglit , Wyartit and Zellerit the "group of uranyl carbonates" with the system no. Vb / D.04 formed.
In the last revised and updated Lapis mineral directory by Stefan Weiß in 2018 , which, out of consideration for private collectors and institutional collections, is still based on this classic system of Karl Hugo Strunz , the mineral was given the system and mineral number. V / F.02-40 . In the "Lapis Classification" this department "uranyl carbonate [UO corresponds 2 ] 2+ - [CO 3 ] 2- " where Andersonit with Agricolait , Bayleyit, Čejkait , Fontanit, Grimselit , Leószilárdit , liebigite, Metazellerit, and Swartzit Zellerit forms an independent but unnamed group.
The 9th edition of Strunz's mineral systematics , which has been valid since 2001 and updated by the International Mineralogical Association (IMA) until 2009, assigns andersonite 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 uranyl to carbonate complex , so that the mineral can be found according to its composition in the sub-section "UO 2 : CO 3 = 1: 4", where it is the only member of the unnamed group 5.ED .30 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the andersonite to the common class of "carbonates, nitrates and borates" and there in the department of "hydrous carbonates" like the outdated Strunz system. Here he is the only member of the unnamed group 02/15/05 within the subdivision “ Hydrogen carbonates with A + m B 2+ n (XO 3 ) p x (H 2 O), (m + n): p> 1: 1 ”.
Crystal structure
Andersonite crystallizes trigonal in the space group R 3 m (space group no. 166) with the lattice parameters a = 18.009 Å and c = 23.838 Å as well as 18 formula units per unit cell .
The crystal structure of natural andersonite has not yet been clarified; there are only studies on synthetic material.
properties
The mineral is radioactive due to its uranium content of up to 37% . Taking into account the proportions of the radioactive elements in the idealized empirical formula as well as the subsequent decays of the natural decay series , a specific activity of around 66.1 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.
Andersonite fluoresces light green under short-wave (254 nm) and turquoise under long-wave (366 nm) UV light .
Education and Locations
Andersonite forms secondarily in the oxidation zone of uranium-containing hydrothermal polymetallic deposits . It is often found in the form of crusty coatings in the mine passages and can also arise from post-mining mineralization . As accompanying minerals may include Bayleyit , Boltwoodit , gypsum , liebigite , schröckingerite and Swartzit occur.
As a rare mineral formation, Andersonite could only be detected in a few samples, with around 50 locations being documented so far (as of 2019), most of which are in the United States . In addition to its type locality , the Hillside Mine near Baghdad in Yavapai County , the mineral occurred in Arizona at Cameron in Coconino County. Other finds are known from Colorado (Bull Canyon, Gateway, Slick Rock), Nevada (Reese River District), Pennsylvania (Mount Pisgah, Jim Thorpe ) and Utah ( Delta in Emery County, Moab , Grand County , Thompsons District, Blanding) , Cane Creek, Cane Springs, White Canyon District).
The sub-district Ambrosia Lake in McKinley County of New Mexico , where crystals up to one centimeter in size were found, is particularly noteworthy due to the extraordinary andersonite finds.
In Germany, Andersonite has so far only been found in the Drosen mine near Ronneburg in Thuringia and the only known site in Austria is the Haidbachgraben (also Myrthengraben ) in the municipality of Semmering on the southern border of Lower Austria.
In the Czech Republic, the mineral has so far been found at the three sites of Předbořice (district of Černíny , Kutná Hora), Jáchymov (Karlovy Vary) and Rožná (Žďár nad Sázavou).
Other previously known finds for andersonite with two localities are known from England in the United Kingdom and with one locality each from Argentina, Greece, France, Italy, Japan, Romania, Sweden, Slovakia, Spain and Hungary.
Precautions
Due to the toxicity and the strong radioactivity of the mineral, mineral samples from andersonite should only be kept in dust- and radiation-proof containers, but especially never in living rooms, bedrooms or work rooms. 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
- Richard V. Gaines, H. Catherine W. Skinner, Eugene E. Foord, Brian Mason , Abraham Rosenzweig: Dana's New Mineralogy . 8th edition. John Wiley & Sons, New York et al. 1997, ISBN 0-471-19310-0 , pp. 466 .
Web links
- Mineral Atlas: Andersonite (Wiki)
Individual evidence
- ^ A b c JM Axelrod, FS Grimaldi, C. Milton, KJ Murata: The uranium minerals from the Hillside mine, Yavapai County, Arizona . In: American Mineralogist . tape 36 , 1951, pp. 1–22 (English, available online at rruff.info [PDF; 1,3 MB ; accessed on April 30, 2019]).
- ^ A b c d e David Barthelmy: Andersonite Mineral Data. In: webmineral.com. Retrieved April 30, 2019 .
- ↑ a b 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 .
- ↑ a b c Andersonite . 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; 68 kB ; accessed on April 30, 2019]).
- ↑ a b c Andersonite. In: mindat.org. Hudson Institute of Mineralogy, accessed April 30, 2019 .
- ↑ a b Helga Kuhlmann, Gerhard Schweigardt: The mysterious world of UV minerals. A special kind of identification book . Christian Weise Verlag, Munich 2016, p. 38 .
- ↑ Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF 1703 kB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed April 30, 2019 .
- ^ A. Coda, A. Della Giusta, V. Tazzoli: The structure of synthetic andersonite, Na 2 Ca [UO 2 (CO 3 ) 3 ] · xH 2 O (x ~ 5.6) . In: Acta Crystallographica . B37, 1981, p. 1496–1500 , doi : 10.1107 / S0567740881006432 (English).
- ↑ Renaud Vochen, Laurent Van Haverbeke, Karel Van Springel: Synthesis of liebigite and andersonite, and study of their thermal behavior and luminescence . In: The Canadian Mineralogist . tape 31 , 1993, pp. 169 (English, available online at rruff.info [PDF; 648 kB ; accessed on April 30, 2019]).
- ↑ Localities for Andersonite. In: mindat.org. Hudson Institute of Mineralogy, accessed April 30, 2019 .
- ↑ Petr Korbel, Milan Novák: Mineral Encyclopedia (= Dörfler Natur ). Edition Dörfler im Nebel-Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 129 .
- ↑ Find location list for andersonite in the Mineralienatlas and Mindat