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Tourmaline has a special place in the hearts of mineral collectors as well as in that of gem and gemstone enthusiasts. Its nearly universal popularity is based upon two very important facts:
It is a bright and beautiful gemstone that can be found in just about any color;
Materials that are of acceptable quality are affordable to most purchasers.
The word "rainbow" is used figuratively to describe tourmaline. In reality, it is a well recognized fact that tourmaline's diversity in color is not limited to the seven colors of the rainbow.
Tourmaline can be colorless to just about any color, hue, or tone known to man. And if range of colors among different tourmalines is not enough, individual crystals can vary in color along their length or in cross-section.
The variations in color along a crystal's length give rise to the bicolor and tricolor tourmalines which have multitudes of color combinations. |
Tourmaline - Main Characteristics
| Classification | Mineral |
| Hardness (Mohs Scale) | 7 |
| Molecular formula | Na(Al,Fe,Le,Mg,Mo)Al(Si6O16)(BO3)4 |
| Composition | Tetrahedra silica. |
| Crystal Shape | Trigonometric. |
| Color/Spectrum | Black, blue, pale red and green gamma. |
| Atomic (Crystal )Structure | Granular. |
| Index of Refraction | 1.62-165 |
| Density (Relative) | 2.55 - 2.58 |
| Light interaction | Vitreous to semi-transparent |
| Uses | Jewelry, ornamental. |
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