Dashkovait
Dashkovait | |
---|---|
General and classification | |
other names |
IMA 2000-006 |
chemical formula | Mg (HCOO) 2 |
Mineral class (and possibly department) |
Organic Compounds - salts of organic compounds |
System no. to Strunz and to Dana |
10.AA.10 ( 8th edition : IX / A.02) 0250-06-02 |
Similar minerals | Formicaite |
Crystallographic Data | |
Crystal system | monoclinic |
Crystal class ; symbol | monoclinic prismatic; 2 / m |
Space group | P 2 1 / c (No. 14) |
Lattice parameters |
a = 8.69 Å ; b = 7.18 Å; c = 9.39 Å β = 97.6 ° |
Formula units | Z = 4 |
Physical Properties | |
Mohs hardness | 1 |
Density (g / cm 3 ) | 1.75 |
Cleavage | Please complete |
Break ; Tenacity | uneven |
colour | White |
Line color | White |
transparency | semi-transparent |
shine | Glass gloss |
Crystal optics | |
Refractive indices |
n α = 1.465 n β = 1.486 n γ = 1.516 |
Birefringence | δ = 0.051 |
Optical character | biaxial (+) |
Other properties | |
Chemical behavior | easily soluble in water |
Dashkovaite is an extremely rare mineral from the mineral class of " organic compounds ". It crystallizes in the monoclinic crystal system with the chemical composition Mg (HCOO) 2 , so from a chemical point of view it is a magnesium formate .
Dashkovaite rarely develops well-defined, tabular crystals . Mostly it forms small, spherical, porous or fibrous mineral aggregates . The largest crystals found so far were about 3 mm in size. The mineral is comparatively soft ( Mohs hardness 1).
Etymology and history
The name of the mineral goes back to the Russian princess and scholar Ekaterina Romanovna Voronzowa-Daschkowa (1743–1810), who was the first woman to head the Russian Academy of Sciences as director. Dashkovait was recognized as a mineral by the International Mineralogical Association (IMA) in 2000 .
After Formicaite , Dashkovaite is the second formate to be officially recognized as a mineral by the IMA.
classification
In the outdated, but still in use 8th edition of the mineral classification according to Strunz , the dashkovaite belonged to the mineral class of "organic compounds" and there to the department of "salts of organic acids", where it belongs together with abelsonite , calclacite , earlandite , formicaite, hoganite , julienite , Kafehydrocyanit , Mellit and Paceit the "Mellit-Julienit-Gruppe" with the system no. IX / A.02 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), also classifies the Dashkovait in the "Salts of organic acids" section. However, this is further subdivided according to the salt-forming acid, so that the mineral can be found according to its composition in the sub-section "Acetate", where it is the only member of the unnamed group 10.AA.10 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Dashkovait to the class and department of the same name of "organic minerals". Here it is together with Formicait in the "Formicait series" with the system no. 50.02.06 within the sub-section of " Salts of organic acids (mellitates, citrates, cyanates and acetates) ".
Crystal structure
Dashkovaite crystallizes monoclinically in the space group P 2 1 / c (space group no. 14) with the lattice parameters a = 8.69 Å , b = 7.18 Å, c = 9.39 Å and β = 97.6 ° and 4 Formula units per unit cell .
properties
Like formicait , dashkovait is easily soluble in water and therefore not stable. The hygroscopic crystals in the air at high humidity to dissolve .
From a chemical point of view, dashkovait is the magnesium salt of formic acid , with the chemical formula Mg (HCOO) 2 . Even if Dashkovait is the salt of an organic acid, its formation is not necessarily linked to biological organisms. Magnesium formate can be formed by purely inorganic compounds (see the comparable illustration of calcium formate ).
Education and Locations
Dashkovait has so far only been detected in one iron deposit in a skarn . In addition to iron and boron minerals, it was found in a salty rock. Associated minerals are: Shabynite , Iowaite , Ekaterinite , Korshunovskite , Halite, and Hydromagnesite .
So far (as of 2013) only two sites in Russia have become known:
- "Korshunovskoye" mine near Schelesnogorsk-Ilimski ( Zheleznogorsk in English ) in the Irkutsk Oblast in eastern Siberia
- "Solongo B" deposit on the Witim plateau in the Republic of Buryatia
See also
literature
- Paul Ramdohr , Hugo Strunz : Klockmann's textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, Stuttgart 1978, ISBN 3-432-82986-8 , p. 736 .
Web links
- Mineral Atlas: Dashkovaite
- Webmineral - Dashkovaite Mineral Data
- Mindat - Dashkovaite mineral information and data
- American-Mineralogist-Crystal-Structure-Database - Dashkovaite
Individual evidence
- ↑ Dashkovaite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 66.5 kB )
- ↑ a b K. Osaki, Y. Nakai, T. Watanabe: The crystal structure of magnesium formats dihydrate and manganous formats dihydrate Locality: synthetic In: Journal of the Physical Society of Japan Volume 19 (1964), pp. 717–723 ( Crystal data available online at crystallography.net )
- ↑ List of localities for Dashkovaite in the Mineralienatlas and Mindat