Denisovite
| Denisovite | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula |
|
|
Mineral class (and possibly department) |
Silicates and Germanates |
|
System no. to Strunz and to Dana |
9.HA.85 ( 8th edition : VIII / F.18) 65.02.01.07 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | not defined |
| Space group | not defined |
| Lattice parameters |
a = 30.92 Å ; b = 7.20 Å; c = 18.27 Å β = 95 ° |
| Formula units | Z = 20 |
| Physical Properties | |
| Mohs hardness | 4 to 5 |
| Density (g / cm 3 ) | measured: 2.76; calculated: 2.81 |
| Cleavage | perpendicular to the long axis of the crystals |
| Break ; Tenacity | splintery; brittle |
| colour | greenish gray, silver gray |
| Line color | white to off-white |
| transparency | translucent |
| shine | Pearlescent, silk gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.567 n β = 1.568 n γ = 1.576 |
| Birefringence | δ = 0.009 |
| Optical character | biaxial positive |
Denisovite is a very rarely occurring minerals from the mineral class of "silicates and germanates" with the idealized chemical composition KCa 2 Si 3 O 8 , and is thus chemically F seen a potassium - calcium silicate with additional fluorine - ions . However, since in natural Denisovite samples some of the potassium can be replaced ( substituted ) by sodium and some of the fluorine by hydroxide ions , this is indicated by the corresponding mixed formula Ca 2 (K, Na) [Si 3 O 8 (F, OH) ] expressed.
Denisovit crystallizes in the monoclinic crystal system and usually develops parallel aggregates from needle-like to columnar crystals from 10 to 15 cm in size. The mineral is greenish-gray to silver-gray in color, translucent in aggregate form and has a pearly to silk-like sheen on the surface .
Etymology and history
Denisovit was first discovered in 1982 in a natrolite tunnel on the southern slope of the Eweslogtschorr and in the Material'naya tunnel on Yukspor in the Chibinen in Murmansk Oblast on the Russian Kola Peninsula . Both sites are therefore considered a type locality for Denisovit.
The mineral was scientifically described by Yuri P. Men'shikov, who named it after Aleksander Petrovich Denisow (Александр Петрович Денисов, 1918–1972), a Russian specialist in X-ray examinations of minerals at the Apatity Science Center, Kola. The complete mineral description and the chosen name has been submitted to the International Mineralogical Association (IMA) for examination (IMA accession number : 1982-031 ) and approved. The publication of the new discovery followed in 1984 in Russian in the specialist magazine Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva and was presented a year later under the heading New Minerals in the American Mineralogist .
Type material of the mineral was found in the Geological Museum of the Science Center of the Russian Academy of Sciences in Apatity on Kola under the catalog no. 557 / 1-2; at the Mining Institute in Saint Petersburg under catalog no. 1295 / 1-2; in the Mineral Preserve Museum in Miass under catalog no. 5392; in the Fersman Museum in Moscow under catalog no. 82762 and vis4773 and in the Natural History Museum in London under catalog no. 1994.7 kept.
classification
In the 8th edition of the mineral systematics according to Strunz , which is out of date, but still in use , Denisovite belonged to the mineral class of "silicates" and there to the department of "chain silicates and band silicates (inosilicates)", where together with bustamite , cascandite , ferrobustamite , foshagite , jennite , Pektolith , Serandit , Tanohatait , Vistepit and wollastonite the "Wollastonitgruppe" with the system no. VIII / F.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 Denisovite to the class of "silicates", although there it belongs to the department of "unclassified silicates". This is further divided by type of participating cations or metals , so that the mineral according to its composition in the subsection "With alkali and alkaline earth elements" is to find where it is the only member of the unnamed group 9.HA.85 forms .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Denisovite to the class of "silicates" and there in the department of "chain silicate minerals". Here it is in the " wollastonite group " with the system no. 65.02.01 to be found in the subsection "Chain Silicates: Simple unbranched chains, W = 1 with chains P = 3".
Crystal structure
Denisovite crystallizes monoclinically in a previously undefined space group with the lattice parameters a = 30.92 Å ; b = 7.20 Å; c = 18.27 Å and β = 95 ° and 20 formula units per unit cell .
Education and Locations
Denisovite forms in nepheline syenite in a differentiated alkali rock massif.
At its type locality in the Chibinen, in addition to nepheline, potassium feldspar , aegirine , apatite , biotite , fluorite and yuksporite were found as accompanying minerals . At the only other known site (as of 2017), the Murun massif in the Aldan highlands in the Sakha Republic (Yakutia) in the Far East of Russia, kalsilite was added as an accompanying mineral.
See also
literature
- Юрий П. Менъшиков (Yuri P. Men'shikov): Денисовит Ca 4 (K 1.4 Na 0.6 ) 2 Si 6 O 16 (F, OH) 2 - новый минерал из хибинского массива . In: Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva . tape 113 , no. 6 , 1984, pp. 718–723 ( rruff.info [PDF; 396 kB ; accessed on November 29, 2017]).
- Pete J. Dunn, James A. Ferraiolo, Michael Fleischer, Volker Gobel, Joel D. Grice, Richard H. Langley, James E. Shigley, David A. Vanko, Janet A. Zilczer: New mineral names . In: American Mineralogist . tape 70 , 1985, pp. 1329–1335 ( rruff.info [PDF; 713 kB ; accessed on November 29, 2017]).
Web links
- Mineral Atlas: Denisovit (Wiki)
- Webmineral - Denisovite (English)
- RRUFF Database-of-Raman-spectroscopy - Denisovite (English)
Individual evidence
- ↑ 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 .
- ↑ a b IMA / CNMNC List of Mineral Names; September 2017 (PDF 1.67 MB)
- ↑ a b c d Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 656 .
- ↑ a b c d Denisovite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 72 kB ; accessed on November 29, 2017]).
- ↑ a b c d Mindat - Denisovite (English)
- ↑ Mineral Atlas : Type locality Eweslogchorr (Eveslogchorr), Chibiny (Khibiny), Kola Peninsula, Northwestern Federal District
- ↑ Mineralienatlas : Type locality Material'naya-Stollen, Yukspor, Chibiny (Khibiny), Kola-Peninsula, Federal District Northwest Russia
- ↑ Find location list for Denisovite in the Mineralienatlas and in Mindat