Sassolin
| Sassolin | |
|---|---|
 |
|
| General and classification | |
| chemical formula | B (OH) 3 or H 3 [BO 3 ] |
|
Mineral class (and possibly department) |
Borates (formerly oxides and hydroxides, see classification ) |
|
System no. to Strunz and to Dana |
6.AA.05 ( 8th edition : IV / F.01) 03/24/01/01 |
| Similar minerals | Behoit , Klinobehoit , Borax , Kernit , Metaborit |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triclinic-pinacoidal, 1 |
| Room group (no.) | P 1 (No. 2) |
| Lattice parameters |
a = 7.09 Å ; b = 7.04 Å; c = 6.35 Å, α = 92.49 °; β = 101.46 °; γ = 119.76 ° |
| Formula units | Z = 4 |
| Frequent crystal faces | {001} |
| Twinning | often, twin axis [001] |
| Physical Properties | |
| Mohs hardness | 1 |
| Density (g / cm 3 ) | measured: 1.46 to 1.50; calculated: 1.562 |
| Cleavage | completely after {001} |
| Break ; Tenacity | undefined, crystals and split leaves flexible |
| colour | colorless, white, gray or yellow to brown due to impurities |
| Line color | White |
| transparency | transparent |
| shine | Glass luster, mother-of-pearl luster on split surfaces |
| Crystal optics | |
| Refractive indices |
n α = 1.340 n β = 1.456 n γ = 1.459 |
| Birefringence | δ = 0.1190 |
| Optical character | biaxial negative |
| Axis angle | 2V = 16.2 ° (calculated); 5 ° (measured) |
| Other properties | |
| Chemical behavior | Easily soluble in water |
| Special features | sometimes fluorescent , "teratogenic" and "impairing fertility" |
Sassolin is a rather seldom occurring mineral from the mineral class of borates (formerly oxides and hydroxides , see classification ). It crystallizes in the triclinic crystal system with the composition B (OH) 3 or H 3 [BO 3 ] and is therefore the naturally occurring form of orthoboric acid .
Sassolin mainly develops colorless and transparent crystals with a platelet to tabular, pseudo-hexagonal habit . When contaminated with sulfur, it can also turn yellow and with iron oxides brown. However, its line color is always white.
Special properties
Sassolin is easily soluble in water and has a salty to bitter taste. Some Sassolines show a blue fluorescence under short-wave UV light .
Etymology and history
The name Sassolin is derived from the site and today's type locality Sasso near Larderello ( Tuscany , Italy ), which is located in the so-called Valley of the Devil (Italian: valle del diavolo ). This geothermally very active region is characterized by numerous sulfur- and boron-containing fumaroles , the so-called soffions . The first description of the mineral dates to the beginning of the 19th century.
Since the founding of the International Mineralogical Association , Sassolin (English Sassolite ) has been the internationally recognized mineral name for the naturally occurring boric acid.
classification
In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the Sassolin belonged to the mineral class IV of the " oxides and hydroxides " and there to the department of "hydroxides and oxidic hydrates", where together with Behoit and Klinobehoit it belongs to the unnamed group IV /F.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 Sassolin to the class of " borates " and there in the department of "monoborates". This section is further subdivided according to the form of the borate complex and the possible presence of additional anions , so that the mineral can be found according to its composition in the sub-section "BO 3 without additional anions", where it is the only member of the unnamed group 6.AA. 05 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Sassolin to the common class of "carbonates, nitrates and borates" and there in the division of "anhydrous borates with (A) 2+ XO 4 ". Here he is the only member of the unnamed group 24.03.01 within the subdivision of the “[[Systematics of Minerals according to Dana / Carbonates, Nitrates, Borates # 24.03 Anhydrous borates with (A) m (B) n [XO3] p | Anhydrous Borates with (A) m (B) n [XO 3 ] p ]] ”.
Education and Locations
Sassolin is formed by crystallization from condensed , boric acid-containing water vapor and is usually found on fumaroles in volcanically active areas. At correspondingly high Borsäuregehalten local can in these areas Bor - deposits arise. Accompanying minerals ( parageneses ) of Sassolin are often native sulfur , realgar and various iron oxides .
In addition to the type locality near Larderello , Sassolin can also be found in Italy on Vesuvius and on the Aeolian Islands . The region around Aachen / North Rhine-Westphalia in Germany , Ladakh in India , the region around Kagoshima in Japan , the Kamchatka peninsula in Russia , as well as Death Valley / California, Yellowstone National Park / Wyoming and Washoe County / Nevada in the can be found as further locations USA are called.
morphology
Sassolin usually crystallizes in the form of flake-like platelets with a pseudo-hexagonal symmetry. This hexagonal cross-section of the platelets is caused on the one hand by the γ-angle which is close to 120 °, on the other hand by the strong tendency to form twins of the crystals, whereby several individuals appear macroscopically as one crystal. The crystals reach a size of up to 5 mm. Needle-shaped crystals that grow stalactite-like , hanging from rock surfaces, are rarer.
Crystal structure
 Unit cell from Sassolin |
||
| Crystal system | triclinic | |
| Space group | P 1 | |
|
Lattice parameter (unit cell ) |
a = 709 pm b = 704 pm c = 635 pm |
α = 92.49 ° β = 101.46 ° γ = 119.76 ° |
| Number (Z) of the formula units |
Z = 4 | |
Sassolin crystallizes in the triclinic crystal system in the space group P 1 with the lattice parameters a = 709 pm , b = 704 pm, c = 635 pm; α = 92.49 °, β = 101.46 ° and γ = 119.76 ° as well as four formula units per unit cell .
The crystal structure has a pronounced layer-like character. The individual trigonal planar (see also VSEPR model ) constructed boric acid - molecules are perpendicular to the crystallographic c aligned axis ([001]) and form via hydrogen bonding layers parallel to the (001) plane (a-b plane). There are only very weak intermolecular interactions between these layers, which explains the perfect cleavage parallel to the (001) plane and the very low Mohs hardness of 1.
Precautions
Since boric acid is toxic to reproduction , i.e. H. "Damaging to fertility" and "impairing fertility" apply, mineral samples should be kept in dust-tight containers and absorption into the body ( incorporation , ingestion ) should be prevented in any case and direct body contact avoided for safety. The limit value for dust is 0.5 mg / m 3 boron, corresponding to 3 mg / m 3 Sassolin; for comparison some general dust limit values .
See also
literature
- Martin Okrusch, Siegfried Matthes: Mineralogy. An introduction to special mineralogy, petrology and geology . 7th fully revised and updated edition. Springer Verlag, Berlin et al. 2005, ISBN 3-540-23812-3 , pp. 171 .
Web links
- Mineral Atlas: Sassolin (Wiki)
Individual evidence
- ↑ a b IMA / CNMNC List of Mineral Names - Sassolite (PDF 1.8 MB; p. 250)
- ^ A b 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. 328 .
- ↑ a b c d M. Gajhede, S. Larsen, S. Rettrup: Electron density of orthoboric acid determined by X-ray diffraction at 105 K and ab initio calculations. In: Acta Crystallographica . No. B42, 1986, pp. 545-552
- ↑ Webmineral - Sassolite
- ↑ a b John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Sassolite , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 65.5 kB )
- ^ Helmut Schrätze, Karl-Ludwig Weiner: Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 479-480 .
- ↑ a b c Mindat - Sassolite
- ↑ Mindat - Localities for Sassolite
- ↑ Data Boric acid for analysis (PDF) at Merck , accessed on 27 October 2014 .