Prase
A variety of Quartz
What is Prase?
The term "prase" refers to a translucent, leek-green type of quartz, most commonly quartzite, but also some true quartzes and jaspers of similar color. The term is no longer considered to have much scientific meaning, since it covers so many differing types of rocks. Stones of this beautiful color have been carved for decorative purposes since ancient Greece.
Uses & Applications
The second-most valuable variety of chalcedony, prase was a known gem in the times of ancient Greeks and Romans. Today, it is mostly used for making attractive green cabochons and beads. Sometimes pieces of prase are clear enough to be cut into faceted stones. Its availability in the market is limited.
Optical Properties
- Refractive Index
- 1.544-1.553
- Birefringence
- 0.009
- Pleochroism
- Weakly dichroic
- Optical Character
- Biaxial positive
- Dispersion
- 0.013
Prase Market Value Calculator
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Prase Localities Map
See where Prase is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
The Meaning
During the Middle Ages, it was believed that this stone had healing and protective properties.
Health & Safety Information
- ⚠️Harm Reason: Prase in powdered form can be toxic due to its Crystalline Silica content.
- ⚠️Physical Toxicity: Quartz, silica, crystalline silica and flint are non-toxic materials, but very fine dust containing quartz, known as respirable crystalline silicon (RCS), can cause serious and fatal lung disease. Lapidaries should exercise caution when cutting silica.
- ⚠️How to prevent the risks of Prase?
Quick Facts
Physical Properties
- Color
- Leek-green
- Hardness (Mohs)
- 6.5 - 7
- Density
- 2.64 - 2.69 g/cm³
- Streak
- White
- Luster
- Greasy, Vitreous
- Crystal System
- Trigonal
Chemical Properties
- Chemical Formula
- SiO2
- Elements
- Si, O
Also Known As
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