Ortit ( other Greek: ὀρθός - direct, regular) is a rare mineral of the island structure of the group of silicates of the epidote group. It was discovered in 1810 by the Scottish mineralogist Thomas Allan (1777-1833). Received the name in 1818 due to the prismatic form of crystals . It has many synonyms : allanite (in honor of the discoverer), bagrationite, bodenite, muromontite, tautotite, cerine, cerepidot.
| Ortit | |
|---|---|
 California orthitis | |
| Formula | (Ca, Ce, La, Y) 2 (Al, Fe) 3 (SiO 4 ) 3 (OH) |
| Physical properties | |
| Colour | Brown to black |
| Trait color | White - Pale Green |
| Shine | Metallic or oily, and glass in fracture |
| Hardness | 5.5-6 |
| Cleavage | Imperfect |
| Kink | Fragile, fragile |
| Density | 3.3-3.8 g / cm³ |
| Syngonia | Monoclinic |
Content
Properties
Contains a significant amount of rare elements: Ce , La , Dy , Er , V. The chemical formula is (Ca, Ce, La, Y) 2 (Al, Fe) 3 (SiO 4 ) 3 (OH). Percentage (in the Ural pegmatites ): CaO - 10.43; Ce 2 O 3 - 10.13; MnO 2.25; FeO - 8.14; Fe 2 O 3 - 6.29; MgO - 0.13; Al 2 O 3 - 16.25; SiO 2 - 30.81; H 2 O - 2.79. The color is brown to black. Gloss from the surface is often metal-like or oily, and in the fracture glass. The fracture is conchoid. The density of 3.3-3.8. Hardness 5.5-6. Radioactive Strong pleochroism (red-brown - brown-golden - green-brown). No luminescence .
The crystals are thick table. It occurs mainly in crystalline silicate rocks : granites , gneisses , syenites , crystalline schists , usually in the form of grains.
Varieties
- beryllium orthite (contains up to 6% BeO);
- orthitis-epidote (intermediate in composition between orthitis and epidote);
- yttrium orthite (contains up to 8% Y 2 O 3 );
- magnesium orthite (contains up to 15% MgO);
- manganese orthite (contains up to 5.37% MnO);
- scandium orthitis (contains up to 1% Sc 2 O 3 );
- thorium orthite (contains up to 5.6% ThO 2 );
- cerite orthite (contains up to 20% Ce 2 O 3 ).
Application
It is an ore of rare earth metals and thorium. Appreciated by collectors . Due to the dark color, it is rarely used in jewelry .
Deposits
Locations: Norway , Sweden , Finland , the Urals (called the Ural orthite), Ukraine ( Priazovye ), USA ( California , Virginia ), Canada , Madagascar .