Teschemacherit
| Teschemacherit | |
|---|---|
| General and classification | |
| other names |
|
| chemical formula |
|
|
Mineral class (and possibly department) |
Carbonates and nitrates |
|
System no. to Strunz and to Dana |
5.AA.25 ( 8th edition : V / B.01) 01/13/03/01 |
| Crystallographic Data | |
| Crystal system | orthorhombic |
| Crystal class ; symbol | orthorhombic-dipyramidal; 2 / m 2 / m 2 / m |
| Room group (no.) | Pccn (No. 56) |
| Lattice parameters | a = 7.25 Å ; b = 10.71 Å; c = 8.75 Å |
| Formula units | Z = 8 |
| Physical Properties | |
| Mohs hardness | 1.5 |
| Density (g / cm 3 ) | measured: 1.45; calculated: 1.545 |
| Cleavage | completely after {110} |
| Break ; Tenacity | brittle |
| colour | colorless, white, light yellow |
| Line color | White |
| transparency | transparent |
| shine | Please complete |
| Crystal optics | |
| Refractive indices |
n α = 1.423 n β = 1.536 n γ = 1.555 |
| Birefringence | δ = 0.132 |
| Optical character | biaxial negative |
| Axis angle | 2V = 41 ° (measured); 40 ° (calculated) |
| Other properties | |
| Chemical behavior | soluble in water, decomposes in a moist environment |
Teschemacherite , also known by its chemical name ammonium bicarbonate or ammonium hydrogen carbonate , is a very rarely occurring mineral from the mineral class of " carbonates and nitrates " (formerly carbonates, nitrates and borates). It crystallizes in the monoclinic crystal system with the chemical composition NH 4 CO 2 ( OH ).
Teschemacherite could only be found in the form of fine crystalline or granular to coarse mineral aggregates . In its pure form it is colorless and transparent or white due to multiple refraction due to its polycrystalline formation. However , the mineral can also take on a light yellow color through foreign admixtures.
Special properties
Teschemacherite is easily soluble in water and decomposes in a moist environment . Mineral samples should therefore be stored away from moisture.
Etymology and history
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Teschemacherite was first discovered in Saldanha Bay on the southwest coast of South Africa and described in 1846 by the British chemist Edward Frederick Teschemacher (1791–1863), albeit under its chemical name ammonium bicarbonate (English Bicarbonate of Ammonia ). James Dwight Dana named the new mineral in 1868 after the person who first described it.
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the Teschemacherite belonged to the mineral class of "carbonates, nitrates and borates" and there to the division of "anhydrous carbonates [CO 3 ] 2− without foreign anions ", where it belonged together with Kalicinite , Nahcolith , Natrite , Wegscheiderite and Zabuyelit the "Nahcolith Kalicinite Group" with the system no. V / B.01 formed.
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), assigns Teschemacherite to the reduced class of “carbonates and nitrates”, but there also to the section of “carbonates without additional anions; without H 2 O “. However, this is further subdivided according to the affiliation of the cations involved to certain element groups , so that the mineral can be found according to its composition in the sub-section " Alkali carbonates", where it is the only member of the unnamed group 5.AA.25 .
Also the systematics of minerals according to Dana , which is mainly used in the English-speaking area , assigns the Teschemacherite, like the outdated Strunzian systematics, to the common class of "carbonates, nitrates and borates" and there in the department of "carbonates". Here he is the only member of the unnamed group 01/13/03 within the sub-section “ Acid carbonates with various formulas ”.
Education and Locations
Teschemacherit forms in guano - deposits . Paragenesis are not yet known.
Due to its extreme rarity, so far (as of 2013) only a few samples of Teschemacherite have been found at a total of five sites and its type locality Saldanha Bay is the only known site in South Africa to date.
Other well-known sites are on the west coast of Patagonia in Argentina, in Azerbaijan , in the geothermal area of Broadlands on the North Island of New Zealand and on Isla Guañape and the Chincha Islands in Peru.
Crystal structure
Teschemacherite crystallizes orthorhombically in the space group Pccn (space group no. 56) with the lattice parameters a = 7.25 Å ; b = 10.71 Å and c = 8.75 Å and 8 formula units per unit cell .
On the basis of a synthetically produced material sample , the Austrian crystallographer Franz Pertlik was able to create a refined structural analysis of Teschemacherite. According to this, the crystal structure of the mineral consists of [CO 2 (OH)] - chains, which run parallel to the c-axis and are connected to the [NH 4 ] + groups via hydrogen bonds to form a three-dimensional framework.
See also
literature
- EF Teschemacher: Philosophical Magazine and Journal of Science , Volume 28 (1846), p. 548
- 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. 719 .
Web links
Individual evidence
- ↑ a b c F. Pertlik: Refinement of the crystal structure of Teschemacherite, NH 4 CO 2 (OH) , In: Tschermaks mineralogische und petrographische Mitteilungen 1981, Volume 29, Edition 2, pp. 67-74 doi : 10.1007 / BF01084698
- ↑ 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. 285 .
- ↑ Webmineral - Teschemacherite
- ↑ a b Teschemacherite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 64 kB )
- ↑ a b c Mindat - Teschemacherite
- ^ The Mineralogical Record - Edward F. Teschemacher
- ↑ Mindat - list of locations for Teschemacherite