TheTourmaline-group
consists of euhedral
(with the same structure of crystal lattice) trigonal crystallizing mineral
specimens with a similar chemical structure and the grade of hardness 7,5-8.
The minerals are: dravite, uvite, tsilaisite, elbaite, buergerite, schoerl
und liddicoatite. The colours of tourmalines vary from colourless to brownish,
pinkish, yellowish and greenish.
According to their colour, tourmaline has
different names:
indigolite --- blue
verdelite --- green
rubelite --- red
schörl ---
black
achroite --- colourless
Due
to its variety of colous, its hardness and its high refractive index,
tourmaline is one of the most longing gems.
The
Tourmaline-group
consists of euhedral
(with the same structure of crystal lattice) trigonal crystallizing mineral
specimens with a similar chemical structure and the grade of hardness 7,5-8.
The minerals are: dravite, uvite, tsilaisite, elbaite, buergerite, schoerl
und liddicoatite. The colours of tourmalines vary from colourless to brownish,
pinkish, yellowish and greenish.
Due
to its variety of colous, its hardness and its high refractive index,
tourmaline is one of the most longing gems.