The tourmaline is a kind of silicic acid rock mineral. As its Chinese craft name ”°Bixi”±, which means valuable gem,the tourmaline is ranked among the middle level gems,The crystal structure and formation of the tourmaline: trigonal system, compound single pyramid trigonal system, prism crystal; the two ends have different crystal surface. Usually, There are vertical lines on the surface of the prism, and the transect is spherical triangle. The shape of the aggregate is like stick, emanant, or bundle of needles, and sometimes it is dense massive or hidden crystal massive.
Generally the tourmaline is contained in the pegmatite, albite, lepidolite, and greisen. Usually the tourmaline has the phenomenon of colorful ribbon, with colorless line trace, luster of glass, and cannot be separated into slice. Hardness: 7.0-7.5, possessing brittleness, specific gravity:3.03-3.25, with piezoelectricity and pyroelectricity, the tourmaline shows no or little fluorescence under the shining of the ultraviolet. The red one may send out feeble purple fluorescence. Under the transmission light of the microscope it will show pleochroism.
The chemical components of the fiber like tourmaline:
SiO2 TiO2
CeO
K2O
LiO
Al2O3
B2O3
41.56%
0.26%
0.52%
0.14%
1.87%
26.30%
9.33%
MgO
Na2O
Fe2O3
FeO
MnO
P2O5
0.55%
1.20%
12.19%
5.85%
0.04%
0.22%
The chemical components of the aggregate crystal tourmaline:
Al2O3 SiO2
Fe2O3
B2O3
MgO
CaO
K2O
Na2O
35.42%
35.25%
14.70%
11.15%
0.18%
0.078%
0.028%
0.85%
The chemical components of the single crystal tourmaline:
SiO2 B2O3
Al2O3
Fe2O3
MnO
MgO
CaO
40.02
8.32
41.41
0.48
1.20
0.26
0.41
Na2O
Li2O
Rb2O
F
H2O+
TiO2
1.90
0.85
0.02
1.22
4.30
0.016
|
Home
