Stupid
| Stupid | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | Na 2 Mg [SO 4 ] 2 • 4H 2 O |
|
Mineral class (and possibly department) |
Sulfates (including selenates, tellurates, chromates, molybdates, and tungstates) |
|
System no. to Strunz and to Dana |
7.CC.50 ( 8th edition : VI / C.18) 29.3.3.1 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | P 2 1 / a (No. 14, position 3) |
| Lattice parameters |
a = 11.126 Å ; b = 8.242 Å; c = 5.539 Å α = 90 °; β = 100.84 °; γ = 90 ° |
| Formula units | Z = 2 |
| Frequent crystal faces | {110}, {210}, {110}, {001}, {111}, { 2 11} |
| Physical Properties | |
| Mohs hardness | 2.5 to 3 |
| Density (g / cm 3 ) | measured: 2.218 to 2.24; calculated: 2.23 |
| Cleavage | no |
| Break ; Tenacity | clamshell; brittle |
| colour | colorless, white, dark gray, bluish green, reddish |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.483 n β = 1.486 n γ = 1.487 |
| Birefringence | δ = 0.004 |
| Optical character | biaxial negative |
| Axis angle | 2V = 71 ° (measured); 58 ° (calculated) |
| Other properties | |
| Chemical behavior | soluble in water, bitter taste |
Blödit is a rarely occurring mineral from the mineral class of sulfates (including selenates, tellurates, chromates, molybdates and wolframates). It crystallizes in the monoclinic crystal system with the composition Na 2 Mg [SO 4 ] 2 · 4H 2 O, so it is chemically a water-containing sodium - magnesium sulfate.
Blödit usually develops short, prismatic crystals with a glass-like sheen on the surfaces, but also occurs in the form of granular to massive mineral aggregates . In its pure form it is colorless and transparent. However, due to multiple refraction due to lattice construction defects or polycrystalline formation, it can also appear white and, due to foreign admixtures, take on a dark gray, bluish-green or reddish color, the transparency decreasing accordingly.
Etymology and history
Blödit was first discovered and described in 1821 in Bad Ischler Salzberg in the Upper Austrian Salzkammergut by Johann Friedrich John (1782–1847), who named the mineral after the German chemist Karl August Blöde (1773–1820).
In 1869 the Austrian mineralogist Gustav Tschermak (1836–1927) described a newly discovered mineral and named it Simonyite in honor of the Austrian natural scientist Friedrich Simony . In later investigations, however, it turned out that the new mineral was identical to the already known Blödit, so that the name Simonyit was discredited and is now a synonym for Blödit.
Gustav Rose coined the term astrakanite (also astrakhanite ) in 1837 for the white, opaque and prismatic crystals that he found in the same year at the mouth of the Volga near the city of Astrakhan in Russia. However, these later also turned out to be stupid crystals.
classification
In the now outdated, but still in use 8th edition of the mineral systematics according to Strunz , the Blödit belonged to the department of "hydrous sulphates without foreign anions ", where together with Changoite , Konyaite , Leonite , Mereiterite and Nickelblödit the "Leonite Group" with the System no. VI / C.18 .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns the Blödit to the category of "sulfates (selenates, etc.) without additional anions, with H 2 O". However, this is further subdivided according to the relative size of the cations involved, so that the mineral can be found according to its composition in the sub-section “with medium-sized and large cations”, where the “stupid group” with the system no. 7.CC.50 and the other members Changoit and Nickelblödit forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Blödit to the class of "sulfates, chromates and molybdates" and there in the department of "water-containing acids and sulfates". Here he is also the namesake of the " Blöditgruppe " with the system no. March 29, 2003 within the sub-section “ Hydrous acids and sulphates with (A + ) 2 B (XO 4 ) 2 × x (H 2 O)”.
Crystal structure
Blödit crystallizes monoclinically in the space group P 2 1 / a (space group no. 14, position 3) with the lattice parameters a = 11.126 Å ; b = 8.242 Å; c = 5.539 Å; β = 100.84 ° and α = γ = 90 ° as well as 2 formula units per unit cell .
properties
Blödite crystals must be kept under lock and key, as they (similar to chalcanthite ) weather in the air over time due to dehydration and form a white crust. Furthermore, the material is easily soluble in water.
Education and Locations
Blödit is formed by chemical sedimentation in salt water , i.e. by evaporation- related precipitation of the groups of molecules that form blödit. The accompanying minerals include carnallite , halite , kainite , mirabilite , polyhalite and thénardite .
As a rare mineral formation, Blödit has only been found at a few sites so far, with around 80 sites (as of 2013) being known. In addition to its type locality in Bad Ischler Salzberg, the mineral also appeared in Austria in the municipality of Abtenau (Webing), in the Moldan gypsum works near Grubach and the Dürrnberg rock salt deposit in Salzburg, as well as in the salt mines near Hall in Tyrol and Hallstatt in Upper Austria.
In Germany, Blödit was able to work at Giesel , Neuhof , Heringen and Philippsthal in Hessen; the "Julia" mine near Herne in North Rhine-Westphalia; at Tarthun and Westeregeln in Saxony-Anhalt; can be found in the “Willi Agatz” mining operation of SDAG Wismut near Dresden in Saxony and near Merkers in Thuringia.
Other locations include the Antarctic, Australia, Chile, China, Canada, France, Iceland, Hungary, Italy, Mexico, Namibia, Pakistan, Poland, Russia, Turkey, Turkmenistan, Ukraine, Uzbekistan and several states of the USA .
See also
literature
- Helmut Schrätze, Karl-Ludwig Weiner: Mineralogy. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 590-591 .
- Hans Schulze: Mineralogicals from Tarapacá , In: Negotiations of the German Scientific Association in Santiago , Volume 2 (1889), pp. 49–60 ( PDF 1.08 MB ; historical report on the find situation in Chile)
- Melissa D. Lane: Mid-infrared emission spectroscopy of sulfate and sulfate-bearing minerals , In: American Mineralogist , Volume 92 (2007), pp. 1–18 ( PDF 624 kB ; Spectroscopic data of various sulfates)
- Erich Reiter: The simonyite - a small contribution to the history of a "newly discovered" old mineral ( PDF 803 kB )
Web links
- Mineral Atlas: Blödit (WiKi)
- Webmineral - Blodite (English)
Individual evidence
- ^ 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. 390 .
- ↑ a b c Hawthorne FC: Refinement of the crystal structure of bloedite , The Canadian Mineralogist, Vol. 23, 1985, 669-674 ( PDF )
- ↑ a b c Blödite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 66 kB )
- ↑ a b c Mindat - Blödite (English)
- ↑ The Mineralogical Record - Johann Friedrich John (English)
- ↑ JF John: Chemical decomposition of a new fossil salt, the stupid , In: Chemical investigations of mineral, vegetable and animal substances , Maurer's bookstore, Berlin 1821, pp. 240–247 ( PDF 1.4 MB )
- ↑ Vera MF Hammer: Stupid . In: Austria-Lexikon
- ↑ Gustav Rose (1837): Journey to the Urals, the Altai, and the Caspian Sea , Volume 2, Berlin 1842, pp. 270–271 (available online at archive.org )
- ↑ Mindat - Number of locations for Blödit
- ↑ Find location list for Blödit at the Mineralienatlas and at Mindat