Taramite is a rare mineral from the class of silicates (inosilicates). It was discovered in 1923 by the mineralogist Jozef Morozevich .
| Taramite | |
|---|---|
 | |
| Formula | Na 2 Ca (Fe, Mg) 3 Al 2 (Si 6 Al 2 ) O 22 (OH) 2 |
| Impurity | Ti , Mn , K , F , Cl |
| Physical properties | |
| Color | Various colors |
| Trait color | Gray |
| Shine | Glass |
| Hardness | 5-6 |
| Cleavage | Very perfect |
| Kink | Splitting |
| Density | 3,5 g / cm³ |
| Syngonia | Monoclinic |
| Refractive index | nα = 1.705 nβ = 1.713 nγ = 1.715 |
Content
- 1 Opening and title
- 2 Crystallography and physical properties
- 3 Chemical composition
- 4 Deposits
- 5 Literature
- 6 References
Opening and title
Taramite owes its name to the place of Vali-Taram (a beam on the Kalmius river, the village of Dmitrievka), which is located near Mariupol . Samples of the mineral were found in 1923, on the basis of which the Polish geologist and mineralogist Jozef Morozevich compiled a description of this mineral.
Crystallography and physical properties
Syngonia - Monoclinic
Cell parameters - a = 9.92Å, b = 18.13Å, c = 5.35Å
β = 105.84 °
Ratio - a: b: c = 0.547: 1: 0.295
Unit cell volume - V 925.66 ų (calculated according to unit cell parameters)
Most often, taramite stands out in the form of flat elongated crystals. Sometimes they are compacted in a mass formed by other minerals, mainly silicates . Taramite can form inclusions, for example, in granites . The largest crystals formed upon proper crystallization reach 10 centimeters. The formation of long fibrous crystals is promoted by the internal structure, presented in the form of a double chain of silica tetrahedra , which is characteristic of all inosilicates of the amphibole group . The internal structure determines not only the appearance of crystals, but also a number of physical properties of the mineral. One of these properties is cleavage. The angle between the two cleavage planes is from 120 to 60 °, which gives a constant rhombic section.
The most similar to taramite are richterite , a number of actinolites and tremolite .
Chemical Composition
One of the characteristic features of taramite is its complex chemical composition. There are a number of impurities that slightly change the physical properties of the mineral (titanium, manganese, potassium, fluorine, and chlorine). During substitutions, stronger changes are observed, which can lead to the formation of new minerals. Examples are magnesiotaramite, in which a significant part of the iron atoms is replaced by magnesium, and ferrotaramite , in which a significant part of the aluminum is replaced by iron, was discovered in 1978.
Deposits
The main rocks of the occurrence of taramite are nepheline syenites and alkaline gneisses , where it forms dikes and veins. Taramite is also commonly found in eclogites . The main deposits of taramite are located in Vali-Tarama ( Ukraine ), in the Urals ( Russia ), in the province of Jiangsu ( China ), in Tanzania (Mbozi), Somalia (Borama), in the province of Ontario ( Canada ), in Brazil , Italy (Piedmont) , in the province of Jaen ( Spain ) and the Loire ( France ).
Literature
- Morozewicz J. (1923), Bull. Service géologique Pologne, 2, 6
- Tschermaks Mineralogische und Petrographische Mitteilungen (1925): 38: 210.
- Hawthorne, Frank C., and Roberta Oberti (2006), On the classification of amphiboles: Canadian Mineralogist: 44 (1): 1-21.