Tanzanite

A Tanzanite crystal has distinct pleochroism. It shows either blue, purple, or slate-grey depending on viewing angle of the gemstone. There may also be a slight color change in incandescent light (such as that from a light bulb). That is when the stone appears more violet. Tanzanite has been confused with sapphire. It is interesting to note that the crystal has perfect cleavage.

Occurrence

Tanzanite was first discovered in Tanzania. Pakistan is another source of the stone.

Tanzanite Properties

• Specific Gravity: 3.35
• Refractive Index: 1.69-1.70
• Birefringence (DR): 0.010
• Luster: Vitreous
• Crystal Structure: Orthorhombic
• Composition: Calcium aluminum hydroxysilicate
• Hardness: 6½

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Birthstone

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