Julienit
| Julienit | |
|---|---|
| General and classification | |
| chemical formula | Na 2 Co (SCN) 4 • 8H 2 O |
|
Mineral class (and possibly department) |
Organic compounds |
|
System no. to Strunz and to Dana |
10.AD.05 ( 8th edition : IX / A.02) 02.50.03.01 |
| Crystallographic Data | |
| Crystal system | monoclinic (pseudotetragonal) |
| Crystal class ; symbol | monoclinic prismatic 2 / m |
| Space group | P 2 1 / n |
| Lattice parameters |
a = 18.94 Å ; b = 19.21 Å; c = 5.46 Å β = 91.6 ° |
| Formula units | Z = 4 |
| Twinning | after {110} |
| Physical Properties | |
| Mohs hardness | not known |
| Density (g / cm 3 ) | measured: 1.648; calculated: 1.61 |
| Cleavage | good after {001} |
| colour | blue |
| Line color | blue |
| transparency | translucent |
| shine | Please complete |
| Crystal optics | |
| Refractive indices |
n ω = 1.556 n ε = 1.645 |
| Birefringence | δ = 0.089 |
| Optical character | uniaxial positive |
Julienite (also Juliënite , not to be confused with Julianite , a synonym for Tennantite ) is a very rarely occurring mineral from the mineral class of " organic compounds ". It crystallizes in the monoclinic crystal system with the chemical composition Na 2 Co (SCN) 4 • 8H 2 O and has so far only been found in the form of blue, translucent encrustations of tiny, needle-like crystals on talc shale .
Etymology and history
Julienit was first described in 1928 by Alfred Schoep (1881–1966), who named the mineral after its discoverer Henri Julien († 1920), a Belgian scientist. Schoep mistakenly thought the mineral was a cobalt analogue of buttgenbachite . Later investigations were carried out by de Sweemer in 1932, Cuvelier in 1933, and again by Schoep and Billiet in 1934, but the compositional analysis by Cuvelier and de Sweemer's were more accurate.
The type locality for the Julienite is the Chamibumba (Shamitumba) site near Shinkolobwe in the Congolese province of Katanga .
classification
In the meanwhile outdated, but still in use 8th edition of the systematics of minerals according to Strunz , the julienite belongs to the department of " salts of organic acids ", where together with mellite the namesake of the mellite-julienite group with the other members abelsonite , calclacite , dashkovaite , Earlandite , formicaite , hoganite , cafehydrocyanite and paceite .
Since the new systematics of minerals according to Strunz (9th edition) , which was revised in 2001, this section has been more precisely subdivided according to the salts on which the formula is based and the mineral is accordingly in the " Cyanates " subdivision . Here the Julienit is the only member of the unnamed group 10.AD.05 .
The systematics of minerals according to Dana , which is common in the English-speaking world , also assigns Julienite to the class of organic compounds, but there in the division of " salts of organic acids (mellitate, citrate, cyanate and acetates) ", where it is the only member of the unnamed group 02/50/03 is.
Crystal structure
Julienite crystallizes monoclinically in the space group P 2 1 / n with the lattice parameters a = 18.94 Å ; b = 19.21 Å; c = 5.46 Å and β = 91.6 ° and 4 formula units per unit cell .
properties
Julienit is readily soluble in water and turns it pink.
Education and Locations
So far nothing is known about the exact formation conditions, since the mineral could only be detected at its type locality Shamitumba in Katanga.
See also
Web links
- Mineral Atlas: Julienite (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. 721 .
- ↑ a b c d Handbook of Mineralogy - Julienite (English, PDF 65 kB).
- ↑ Webmineral - Julienite (English).
- ↑ a b c Julienite at mindat.org (engl.)
- ↑ Stefan Weiß: The large Lapis mineral directory . 5th edition. Christian Weise Verlag, Munich 2008, ISBN 3-921656-17-6 .
- ↑ a b V.DC Daltry: Annales de la Société Géologique de Belgique: The Type Mineralogy of Africa: Zaire (Table minerals p.2, full name of the describer S. 3, mineral description on page 10 References A. Schoep S. 28).