Rabbittit

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Rabbittit
General and classification
chemical formula Ca 3 Mg 3 [(UO 2 ) 2 | (OH) 4 | (CO 3 ) 6 ] · 18 H 2 O
Mineral class
(and possibly department) 		Carbonates ( and relatives )
System no. to Strunz
and to Dana 		5.ED.25 ( 8th edition : V / F.04)
16b.07.03.01
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol not defined
Space group not defined
Lattice parameters a  = 32.6  Å ; b  = 23.8 Å; c  = 9.45 Å
β  = ~ 90 °
Formula units Z  = 8
Physical Properties
Mohs hardness 2.5
Density (g / cm 3 ) measured: 2.57; calculated: 2.69
Cleavage completely after {001}
colour light green, greenish yellow
Line color not defined
transparency translucent
shine Silky gloss
radioactivity very radioactive
Crystal optics
Refractive indices n α  = 1.502
n β  = 1.508
n γ  = 1.525
Birefringence δ = 0.023
Optical character biaxial positive
Other properties
Chemical behavior slowly dissolving in water
Special features pale yellow fluorescence under UV light

Rabbittite is a very rarely occurring mineral from the mineral class of the " carbonates ( and relatives )". It crystallizes in the monoclinic crystal system with the chemical composition Ca 3 Mg 3 [(UO 2 ) 2 | (OH) 4 | (CO 3 ) 6 ] · 18 H 2 O and develops mostly small, fibrous and radially radial crystals of light green to yellow-green color .

Etymology and history

Rabbittit was first discovered in 1952 in the "Lucky Strike Mine" No. 2 Emery County / Utah in the USA by Mary E. Thompson, Alice D. Weeks, when they visited the mine with other geologists from the United States Geological Survey (USGS). Together with Alexander M. Sherwood, the two described the mineral in 1955 and named it after the American geologist and then head of the USGS "Trace Elements" department, John Charles Rabbitt (1907–1957).

classification

In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the rabbittite belonged to the mineral class of "carbonates, nitrates and borates " and there to the department of "uranyl carbonates", where it formed an independent group together with Albrechtschraufit , Sharpit and Urancalcarite .

The 9th edition of Strunz's mineral systematics, which has been in force since 2001 and is used by the International Mineralogical Association (IMA), assigns rabbittite to the class of "carbonates and nitrates" (the borates form a separate class here) and there into the department of " Uranyl carbonate ”. However, this section is further subdivided according to the molar ratio between the uranyl compound [UO 2 ] 2+ and the carbonate anion complex [CO 3 ] 2− , so that the mineral is classified according to its composition in the sub-section “UO 2  : CO 3  = 1 : 4 “can be found where it is the only member of the unnamed group 5.ED.25 .

The systematics of minerals according to Dana assigns the rabbittite like the outdated Strunz'sche mineral systematics in the common class of "carbonates, nitrates and borates" and there in the department of "carbonates - hydroxyl or halogen". Here he is the only member of the unnamed group 16b.07.03 within the subdivision “ Carbonates - Hydroxyl or Halogen ”.

Crystal structure

Rabbittite crystallizes monoclinically in a previously undefined space group with the lattice parameters a  = 32.6  Å ; b  = 23.8 Å; c  = 9.45 Å and β ~ 90 ° as well as 8 formula units per unit cell .

properties

The mineral is classified as very radioactive due to its uranium content of up to 32% and has a specific activity of around 57.362 k Bq / g (for comparison: natural potassium 31.2 Bq / g).

Under short-wave UV light , Rabbittit shows a bright, creamy yellow fluorescence , similar to that of neon-colored highlighters .

Rabbittit slowly dissolves in water.

Education and Locations

Rabbittit was found in the form of efflorescence on a pillar interspersed with rich ore near the entrance to the "Lucky Strike Mine" No. 2 found. Begleitminerale include Bieberit , Cobaltocalcit , Fourmarierit , gypsum and sodium and magnesium- Zippeit .

In addition to its type locality "Lucky Strike Mine" near San Rafael in Emery County, Rabbittit was also found in the United States in the "Hideout Mine" in White Canyon in San Juan County (Utah) and in the "Elias Mine" near Jáchymov ( Sankt Joachimsthal ) found in the Czech Republic .

See also

Precautions

Due to the toxicity and the strong radioactivity of the mineral, mineral samples of rabbittite 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 .

Individual evidence

  1. ↑ a b c d 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. 321 .
  2. ↑ a b c Rabbittite at mindat.org (engl.)
  3. ↑ Webmineral - Rabbittite (English)

literature

  • Stefan Weiß: The large Lapis mineral directory . 4th edition. Christian Weise Verlag, Munich 2002, ISBN 3-921656-17-6

Web links