|
Mineralogy :
|
| Tradename(s) |
Indicolite
(Blue/Green), Rubellite (Pink/Red), Schorl
(Black) |
| Family |
Tourmaline |
| Description |
The chief
constituents are silica and alumina in
nearly equal proportions, forming about
three-fourths of the whole. The remainder
consists of boracic acid, ferrous oxide,
manganese oxide, magnesia, lime, soda,
potash, and lithia, which are not all
present, however, in any one specimen.
Tourmaline forms in igneous and metamorphic
rocks and veins. It occurs with lepidolite,
microcline, and spodumene in granite
pegmatites. |
| Mohs |
7
- 7 1/2 |
| Chemical
Composition |
Na(Mg, Fe)3Al6(BO3)3(Si6O18)(OH,F)4
|
| Refractive
Index |
1.616 -
1.652 |
| Specific
Gravity |
3.02 - 3.26 |
| Cleavage |
None |
| Streak |
White |
| Localities |
Sri Lanka,
Madagascar, Brazil, Mozambique, England, and
Maine (State Mineral), California, New
Jersey, New York/U.S.A. |