Rubicline

• IMA 1996-058

• Rb [ AlSi3O8 ]
• (Rb, K) [ AlSi3O8 ]

Rubiklin is a very rarely occurring mineral from the mineral class of " silicates and Germanates " and then a member of the large group of the feldspars. It crystallizes in the triclinic crystal system with the idealized composition Rb [ AlSi3O8 ], and is therefore chemically seen a rubidium - aluminosilicate. Structurally Rubiklin belongs to the framework silicates.

Rubiklin is the rubidium analogue of microcline (K [ AlSi3O8 ] ) and forms a complete solid solution series. Since the mineral was for this reason in nature so far only with a small amount of potassium found, the formula is therefore usually indicated with (Rb, K) [ AlSi3O8 ]. The values ​​given in the parentheses elements rubidium and potassium can be doing in the formula each represent each other (substitution, Diadochie ), but are always in the same proportions to the other components of the mineral.

In its pure form Rubiklin is colorless and transparent or white by multiple refraction due to polycrystalline training. He has so far been found only in the form of microcrystalline ( ≤ 50 microns ), rounded grains.

Special Features

The mineral is characterized by a content of rubidium (Rb ) of up to 20.47 %, which is in the nature to about 27.8% of radioactive 87Rb, classified as weakly radioactive, and has a specific activity of about 183 Bq / g (compared to natural potassium 31.2 Bq / g).

Etymology and history

Was first discovered Rubiklin in the pollucite - and rare earth -containing pegmatites near San Piero ( in Campo) in the municipality of Campo nell'Elba in the Italian region of Tuscany. This has been described mineral in 1998 by David K. Teertstra, Peter Cerny, Frank C. Hawthorne, Julie Pier, Lu -Min Wang, and Rodney C. Ewing, who named it after its content of rubidium and its close relationship to the microcline.

Rubiklin is the first discovered mineral whose essential component is rubidium. Only two other known Rubidiumminerale: Overall, so far (2013 version): The discovered in the same type locality as Rubiklin 2007 Ramanit - (Rb ) and the Voloshinit also in 2007 at the Vasin - Myl'k discovered on the Russian Kola Peninsula.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Rubiklin belonged to the department of " framework silicates ( tectosilicates ), with zeolites ", where he along with Buddingtonit, celsian, Hyalophane, Kokchetavit, microcline, orthoclase, Paracelsian, sanidine and slawsonite the subgroup of " alkali feldspars " with the system no. VIII/J.06 formed within the group of the feldspars.

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the Rubiklin in the newly defined division of the " framework silicates ( tectosilicates ) without zeolitic H2O" one. This is also further divided according to the possible presence of additional anions, so that the mineral is found according to its composition in the subsection " framework silicates ( tectosilicates ) without additional anions ", where it together with adularia, anorthoclase, Buddingtonit, celsian, Hyalophane, microcline, Monalbit, orthoclase and sanidine the " feldspar " with the system no. 9.FA.30 forms.

The mainly common in English-speaking classification of minerals according to Dana assigns the Rubiklin in the department of " framework silicates: Al- Si lattice " field. Here he is with anorthoclase, celsian, Filatovit, Hyalophane, microcline, orthoclase and sanidine in the group of "K (Na, Ba) - feldspars " with the system no. 76.01.01 found within the subdivision "With Al- Si lattice ".

Education and Locations

Rubiklin was found in one to two centimeters in size, rubidium microcline veins. Accompanying minerals occur among others albite, apatite, muscovite, pollucite and quartz.

Apart from its type locality San Piero ( in Campo) in Italy, the mineral has been able (as of 2013) are detected only in the pegmatites at Red Cross Lake in the Canadian province of Manitoba and the Vasin - Myl'k on the Russian Kola Peninsula. Another possible location is Varuträsk near Skelleftea in the Swedish province of Västerbotten, which has as yet not been confirmed.

Crystal structure

Rubiklin crystallizes in the triclinic space group P1 ( Raumgruppen-Nr. 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 °, and four formula units per unit cell.