Rubiklin
| Rubiklin | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1996-058 |
| chemical formula |
|
|
Mineral class (and possibly department) |
Silicates and Germanates - framework silicates |
|
System no. to Strunz and to Dana |
9.FA.30 ( 8th edition : VIII / J.06) 76.01.01.07 |
| Crystallographic Data | |
| Crystal system | triclinic |
| Crystal class ; symbol | triclinic pinacoidal; 1 |
| Space group | P 1 (No. 2) |
| Lattice parameters |
a = 8.81 Å ; b = 13.01 Å; c = 7.18 Å, α = 90.3 °; β = 115.7 °; γ = 88.2 ° |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | 6th |
| Density (g / cm 3 ) | calculated: 2.72 |
| Cleavage | perfect after {001}, good after {010} |
| Break ; Tenacity | brittle |
| colour | colorless |
| Line color | White |
| transparency | transparent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.520 n β = 1.524 n γ = 1.527 |
| Birefringence | δ = 0.007 |
| Optical character | biaxial |
Rubiklin is a very rarely occurring mineral from the mineral class of " silicates and germanates " and there is a member of the large group of feldspars . It crystallizes in the triclinic crystal system with the idealized composition of Rb [AlSi 3 O 8 ], is thus seen a chemically rubidium - aluminosilicate . Structurally, Rubiklin belongs to the framework silicates .
Rubiklin is the rubidium analogue of Mikroklin (K [AlSi 3 O 8 ]) and forms a complete mixed crystal row with it . Since the mineral has only been found in nature with a small amount of potassium for this reason , the formula is usually given as (Rb, K) [AlSi 3 O 8 ]. The elements rubidium and potassium indicated in the round brackets can represent each other in the formula ( substitution , diadochie), but are always in the same proportion to the other components of the mineral.
In its pure form Rubiklin is colorless and transparent or white due to multiple refraction due to its polycrystalline formation. So far it could only be found in the form of microcrystalline (≤ 50 μm), rounded grains .
Etymology and history
Rubiklin was first discovered in the pollucite and rare earth containing pegmatites near San Piero (in Campo) in the commune of Campo nell'Elba in the Italian region of Tuscany. The mineral in 1998 by David K. Teertstra, Peter Černý, Frank C. Hawthorne, Julie Pier, Lu-Min Wang and Rodney C. Ewing, which after its content was described Rubi dium and its close relationship to the micro klin named.
Rubicline is the first mineral discovered, the essential component of which is rubidium. Total (as of 2013) have only been two other Rubidiumminerale known: The 2007 in the same type locality discovered how rubicline Ramanit- (Rb) and also in 2007 at Vasin-Myl'k on the Russian peninsula Kola discovered Voloshinit .
classification
In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the Rubiklin belonged to the department of "tectosilicates (tectosilicates), with zeolites ", where together with buddingtonite , celsian , hyalophane , kokchetavite , microcline , orthoclase , paracelsian , sanidine and Slawsonite, the subgroup of "alkali feldspars" with system no. VIII / J.06 within the group of feldspars .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), classifies the Rubiklin in the newly defined division of “tectosilicates without zeolitic H 2 O”. This is further subdivided according to the possible presence of additional anions , so that the mineral can be found according to its composition in the sub-section “Tectosilicates without additional anions”, where it can be found together with adulara , anorthoclase , buddingtonite, celsian, hyalophane, microclinic , Monalbit , Orthoclase and Sanidine the "feldspar group" with the system no. 9.FA.30 forms.
The systematics of minerals according to Dana , which is predominantly used in the English-speaking world , also classifies the Rubiklin in the department of "framework silicates: Al-Si lattice". Here he is together with Anorthoklas, Celsian, Filatovit , Hyalophan, Mikroklin, Orthoclase and Sanidin in the group of " K (Na, Ba) -Feldspars " with the system no. 76.01.01 to be found in the subsection "With Al-Si grid".
Crystal structure
Rubicline crystallizes triclinic in the space group P 1 (space group no. 2) with the lattice parameters a = 8.81 Å ; b = 13.01 Å; c = 7.18 Å; α = 90.3 °; β = 115.7 ° and γ = 88.2 ° as well as 4 formula units per unit cell .
properties
The mineral is classified as weakly radioactive due to a rubidium (Rb) content of up to 20.47%, which in nature consists of about 27.8% radioactive 87 Rb, and has a specific activity of about 183 Bq / g (for comparison: natural potassium 31.2 Bq / g).
Education and Locations
Rubiklin was found in one to two centimeters large, rubidium-containing microclinic veins. The accompanying minerals include albite , apatite , muscovite , pollucite and quartz .
In addition to its type locality San Piero (in Campo) in Italy, the mineral was previously (as of 2018) only found in the pegmatites at Red Cross Lake and Maskwa Lake in the province of Manitoba and at Opikeigan Lake ( Kenora District ) in the province of Ontario in Canada; can be found at Luolamäki near Somero in south-western Finland and at Vasin-Myl'k on the Russian Kola Peninsula . Another possible location is Varuträsk near Skellefteå in the Swedish province of Västerbotten, which has not yet been confirmed.
See also
literature
- David K. Teertstra, Peter Černý, Frank C. Hawthorne, Julie Pier, Lu-Min Wang, Rodney C. Ewing: Rubicline, a new feldspar from San Piero in Campo, Elba, Italy . In: American Mineralogist . tape 83 , 1998, pp. 1335–1339 (English, rruff.info [PDF; 63 kB ; accessed on December 3, 2018]).
- A. Kyono, M. Kimata: Refinement of the crystal structure of a synthetic non-stoichiometric Rb-feldspar . In: Mineralogical Magazine . tape 65 , 2001, p. 523-531 (English, rruff.info [PDF; 593 kB ; accessed on December 3, 2018]).
Web links
- Mineral Atlas: Rubiklin (Wiki)
- Database-of-Raman-spectroscopy - Rubicline (English)
Individual evidence
- ↑ a b IMA / CNMNC List of Mineral Names - Rubicline (PDF 1.3 MB; February 2013)
- ↑ a b c d e f 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. 694 .
- ↑ a b Webmineral - Rubicline (English)
- ↑ a b c d Mindat - Rubicline (English)
- ↑ Find location list for Rubiklin in the Mineralienatlas and in Mindat