Darapskit
| Darapskit | |
|---|---|
 ( overall size : 4.5 × 2.5 × 1.5 cm) |
|
| General and classification | |
| chemical formula | Na 3 [NO 3 | SO 4 ] · H 2 O |
|
Mineral class (and possibly department) |
Sulphates (selenates, tellurates, chromates, molybdates and tungstates) |
|
System no. to Strunz and to Dana |
7.DG.05 ( 8th edition : VI / D.16) 01/20/01/01 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Room group (no.) | P 2 1 / m (No. 11) |
| Lattice parameters |
a = 10.56 Å ; b = 6.91 Å; c = 5.19 Å β = 102.8 ° |
| Formula units | Z = 2 |
| Twinning | polysynthetic twins according to {100} |
| Physical Properties | |
| Mohs hardness | 2.5 |
| Density (g / cm 3 ) | measured: 2.201 (5); calculated: 2.202 |
| Cleavage | completely according to {010} and {100} |
| Break ; Tenacity | uneven; brittle |
| colour | colorless, white |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.388 n β = 1.479 n γ = 1.486 |
| Birefringence | δ = 0.098 |
| Optical character | biaxial negative |
| Axis angle | 2V = 26 to 28 ° (measured); 28 ° (calculated) |
| Other properties | |
| Chemical behavior | water soluble |
Darapskite is a rarely occurring mineral from the mineral class of the " sulfates " (and relatives, see classification ). It crystallizes in the monoclinic crystal system with the composition Na 3 [NO 3 | SO 4 ] · H 2 O, and is therefore chemically seen a hydrous sodium - nitrate sulphate.
Darapskite usually develops tabular to prismatic crystals of up to ten centimeters in size, but is also found together with other salt minerals in the form of granular mineral aggregates or, less often, as stalactites . In its pure form, Darapskit is colorless and transparent with shiny glass surfaces. However, due to multiple light refraction due to lattice construction defects or polycrystalline design, it can also appear white, with its transparency correspondingly decreasing.
Special properties
Darapskit is easily soluble in water.
Etymology and history
Darapskite was first discovered in the Pampa del Toro near Oficina Lautaro in the Chilean Región de Antofagasta and described in 1891 by August Dietze , who named the mineral after the German-Chilean chemist and mineralogist Ludwig Darapsky (1857-1916).
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the darapskite belonged to the class of "sulfates, chromates, molybdates and tungstates" and there to the general section of " hydrous sulfates with foreign anions ", where together with carloruizite , Fuenzalidait , Georgeericksenit , Humberstonit , Klinoungemachit and Ungemachit the unnamed group VI / D.16 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 the Darapskit to the extended class of "sulfates (selenates, tellurates, chromates, molybdates and wolframates)", but also to the Department of "Sulphates (selenates etc.) with additional anions, with H 2 O". However, this is further subdivided according to the relative size of the cations involved and the predominant anion complexes in the compound, so that the mineral is classified according to its composition in the sub-section “With large to medium-sized cations; with NO 3 , CO 3 , B (OH) 4 , SiO 4 or IO 3 “can be found, where it forms the unnamed group 7.DG.05 as the only member .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Darapskit, on the other hand, to the class of " carbonates , nitrates and borates " and there in the department of "composite nitrates". Here he is to be found as the only member of the unnamed group 01/20/01 within the sub-section “ Compound nitrates with other anions ”.
Education and Locations
Darapskit formed under arid climate conditions as a crack or void fill in solidified regolith and is found mainly in saltpetre - deposits , dry saline soils and -ausblühungen as a component of salt crusts and. As Begleitminerale occur among others anhydrite , bloedite , Epsomite , halite , mirabilite , niter and Nitrokalit .
As a rare mineral formation, Darapskite has so far (as of 2012) only been found at a few sites, with around 20 sites being known. In addition to its type locality Pampa del Toro, the mineral occurred in Chile in a few other places in the Región de Antofagasta and in the Región de Tarapacá (Province of Iquique). It was also found at the salt lakes of Qakilik ( Ruoqiang ) in the Mongolian Autonomous District of Bayingolin in China, in the limestone caves of the Cerna Valley in Romania and in Death Valley (California), the "flower cave" of the Big Bend National Park (Texas ) in the USA.
Crystal structure
Darapskite crystallizes monoclinically in the space group P 2 1 / m (space group no. 11) with the lattice parameters a = 10.56 Å ; b = 6.91 Å; c = 5.19 Å and β = 102.8 ° as well as 2 formula units per unit cell .
See also
literature
- August Dietze : Some new Chilean minerals , In: Zeitschrift für Kristallographie, Mineralogie und Petrographie , Volume 19 (1891), pp. 443-451
- George E. Ericksen, Mary E. Mrose: Mineralogical studies of the nitrate deposits of Chile. II. DARAPSKITE, Na 3 (NO 3 ) (SO 4 ) · H 2 O , In: The American Mineralogist , Volume 55, Sept.-Oct. 1970 ( PDF 1.1 MB )
- 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. 734 .
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke , Stuttgart 1978, ISBN 3-432-82986-8 , pp. 617 (first edition: 1891).
Web links
- Mineral Atlas: Darapskit (Wiki)
Individual evidence
- ↑ a b c d e 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. 410 .
- ↑ Webmineral - Darapskite
- ↑ a b c Darapskite , in: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 66.9 kB )
- ↑ a b c Mindat - Darapskite
- ↑ Mindat - Number of localities for Darapskit
- ↑ Mindat - Locations for Darapskit