Physical Properties and Specifications

• Chemical Composition: Ca₂Al₃(SiO₄)(Si₂O₇)O(OH)

• Hardness: 6 – 7 on the Mohs scale

• Crystal System: Orthorhombic

• Refractive Index: 1.69 – 1.70

• Specific Gravity: 3.35 – 3.40

• Pleochroism: Strong, displaying blue, violet, and burgundy hues

• Fluorescence: Weak fluorescence under UV light

• Cleavage/Fracture: Perfect cleavage in two directions, conchoidal fracture

Color and Quality Classifications

Available Color Ranges

• Primary hues: Blue, violet

• Secondary modifications: Purplish-blue, bluish-purple

• Tone and saturation ranges: Light to dark tones with vivid saturation

• Premium colors: Deep blue with strong violet undertones

• Commercial grades: Light blue to medium blue shades

Clarity Characteristics

• Typical inclusion types: Needle-like inclusions, silk

• Clarity grading standards: Eye-clean to included

• Source-specific features: Unique inclusions that may indicate the origin

1. Eye-clean criteria: No visible inclusions to the naked eye

Source Locations and Material

Historic sources

• Tanzania (specifically the Merelani Hills)

Current production

• The Merelani region remains the primary source of tanzanite.

Source-specific characteristics

• Tanzanite from different mining sites can exhibit variations in color and clarity.

Production trends

• Increasing demand coupled with limited supply has led to rising prices, making tanzanite more sought after.