Picture pending, topas from Viitaniemi, Finland.
|Mineral class||Silicates : Nesosilicates : Topas - staurolite group|
|Habitus||As prismatic crystals with rombic crossection. Vertically striated prism surfaces.|
|Cleavage||Basal perfect. Fracture conchoidal to irregular.|
|Color||Nuances in yellow, blue or pink. Transparent to translucent.|
|Occurance|| In granitic ( especially greissen and clevlandite)
pegmatites, ryolite and quartz dykes. Also as grains in granites that have
been altered by solutions containing fluoride. |
In hydrothermal veins of high temperature type.
|Associates||Fluorite, turmaline, apatite, beryll and cassiterite.|
|Notes|| Very hard. Can be found in alluvial deposits.|
Clear crystals are used as gemstones, where the orange-brown is the most valuable one.
|Variants|| Phyrophysalite - As massive pieces or raw crystals
with mica transformed surfaces.|
Pyknite - is a radiating ????(strålig) type of topas.
|Locations|| There is no known locality of topas in gem
quality in Sweden. However there are a couple of locations with the
pyrophysalite variant in Sweden. |
| To silicate index.
|| Mineral group index.
If you have some questions, suggestions or comments you are welcome to write me a line or two.