Dumortierite
What is Dumortierite?
Dumortierite is a fibrous, typically blue, rarely violet or green, mineral. It is a nesosilicate of aluminum that crystallizes in the orthorhombic crystal system. It is often found in metamorphic rocks rich in aluminum and is sometimes used as a gemstone.
Optical Properties
- Refractive Index
- 1.672-1.685
- Birefringence
- 0.016
- Pleochroism
- Strong, blue to colorless
- Optical Character
- biaxial (-)
- Dispersion
- 0.020
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Dumortierite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Dumortierite Localities Map
See where Dumortierite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
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Quick Facts
Physical Properties
- Color
- Blue, violet, green, colorless, pink, brown
- Hardness (Mohs)
- 7
- Density
- 3.26 to 3.41 g/cm³
- Streak
- Blue, colorless
Chemical Properties
- Chemical Formula
- Al7BSi3O18(OH)3
- Elements
- Silicon, aluminum, boron, oxygen, and hydrogen
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Dumortierite FAQs
How do I identify Dumortierite?
Dumortierite can be identified by its hardness of 7 on the Mohs scale, Blue color. Look for these key characteristics when examining specimens.
What color is Dumortierite?
Dumortierite typically appears in Blue, violet, green, colorless, pink, brown. Color can vary depending on impurities and formation conditions.
How hard is Dumortierite?
Dumortierite has a hardness of 7 on the Mohs scale. This makes it a relatively hard mineral suitable for jewelry.