Dumortierite tumbled
A variety of Dumortierite
What is Dumortierite tumbled?
Dumortierite tumbled is dark blue or green with brown or black speckles throughout. Sometimes, a rare pink variety is found. It has been mistaken for Lapis Lazuli and is sometimes used as its imitation. Dumortierite tumbled is found in a number of places including Austria and across Africa and the USA. It is used for ornamental pieces.
Optical Properties
- Refractive Index
- 1.669-1.723
- Birefringence
- 0.011-0.037
- Pleochroism
- Red-brown crystals - strong trichroism: black, red brown, brown
- Optical Character
- Biaxial negative
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Dumortierite tumbled 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 tumbled Localities Map
See where Dumortierite tumbled is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Quick Facts
Physical Properties
- Streak
- White
Chemical Properties
- Chemical Formula
- Al(Al2O)(Al2O)2(SiO4)3(BO3)
- Elements
- Al, B, O, Si
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