Prase
Prase
Published: June 2014
Modified: November 2021
Prase is a dull green to yellowish green variety of chalcedony, a cryptocrystalline quartz. It is commonly fashioned en cabochon to show off its leek-green color. Prase can be confused with chrysoprase since they are very similar in appearance, but a darker, less saturated color is typically indicative of prase.
General Information
Common Name
Prase
Species
Prase
Transparency
Transparent - Semitranslucent
Dispersion
Strength: None
Refractive Index
1.535-1.539
Birefringence
0.004
Optic Character
Uniaxial
Optic Sign
Positive
Polariscope Reaction
Aggregate (AGG)
Fluorescence
SWUV: Inert
LWUV: Inert
LWUV: Inert
Pleochroism
None
Hardness
6.5-7
Streak
White
Specific Gravity
2.550-2.700 Typical:2.600
Toughness
Excellent
Inclusions
Prase's green color is due to chlorite inclusions, the grayish green color is due actinolite fibers and the blue color is due to crocidolite fibers.
Luster
Vitreous, Greasy
Stability
Good
Fracture
Conchoidal, Granular
Cleavage
None
Chemical Name
silicon dioxide (aka silica)
Chemical Formula
SiO2
Crystal System
Trigonal
Chemistry Classification
Silicate
Prase Colors
-
Green -
Green -
Green
Countries of Origin
Ecuador; United States of America (the); Spain; Greece; Austria; Morocco; Unknown; China; Ireland; Russian Federation (the); Brazil; Italy; Australia; Bulgaria; France; Germany; Nepal; United Kingdom of Great Britain and Northern Ireland (the)
Care
Normal care