Omphacite
A variety of Minerals
What is Omphacite?
Omphacite is a member of the clinopyroxene group of silicate minerals with formula: (Ca, Na)(Mg, Fe, Al)Si2O6. It is a variably deep to pale green or nearly colorless variety of clinopyroxene. It normally appears in eclogite, which is the high-pressure metamorphic rock of basalt. Omphacite is the solid solution of Fe-bearing diopside and jadeite. It crystallizes in the monoclinic system with prismatic, typically twinned forms, though usually anhedral. Its space group can be P2/n or C2/c depending on the thermal history. It exhibits the typical near 90° pyroxene cleavage. It is brittle with specific gravity of 3.29 to 3.39 and a Mohs hardness of 5 to 6.
Etymology & Origins
It was first described in 1815 in the Münchberg Metamorphic complex, Franconia, Bavaria, Germany. The name omphacite derives from the Greek omphax or unripe grape for the typical green color.
Optical Properties
- Refractive Index
- 1.662-1.723
- Pleochroism
- Weak: colorless, very pale green, very pale green, blue-green
- Optical Character
- Biaxial positive
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Omphacite 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.
Omphacite Localities Map
See where Omphacite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
The Meaning
Omphacite is often thought to be a type of jade, and as such, throughout history, it was believed to have the same benefits. It was traditionally thought of by the Mayans and Aztecs as a pain reliever. The Chinese have long believed that omphacite (or Jade) is a heavenly stone that can bring about prosperity whilst shielding its wearers from bad spirits.
Key Characteristics
Composition of Omphacite
Omphacite is the solid solution of Fe-bearing diopside (CaMgSi2O6) and jadeite (NaAlSi2O6). Depending on how much the coupled substitution of (Na, Al)-(Mg-Fe, Ca) happens, the chemical composition of omphacite varies continuously from pure diopside to pure jadeite. Due to the relatively small radius of (Na, Al) atoms, the unit cell volume linearly decreases as jadeite component increases. In addition, the coupled substitution also stiffens the crystals. The bulk and shear modulus linearly increases as jadeite component increases.
Quick Facts
Physical Properties
- Color
- dark green
- Hardness (Mohs)
- 5 - 6
- Streak
- Greenish white
Chemical Properties
- Chemical Formula
- (NaaCabFe2+cMgd)(AleFe3+fFe2+gMgh)Si2O6
Also Known As
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Omphacite FAQs
How do I identify Omphacite?
Omphacite can be identified by its hardness of 5 - 6 on the Mohs scale, dark green color. Look for these key characteristics when examining specimens.
What color is Omphacite?
Omphacite typically appears in dark green. Color can vary depending on impurities and formation conditions.
How hard is Omphacite?
Omphacite has a hardness of 5 - 6 on the Mohs scale. This gives it moderate hardness.
What is the composition of omphacite of Omphacite?
Omphacite is the solid solution of Fe-bearing diopside (CaMgSi2O6) and jadeite (NaAlSi2O6). Depending on how much the coupled substitution of (Na, Al)-(Mg-Fe, Ca) happens, the chemical composition of omphacite varies continuously from pure diopside to pure jadeite. Due to the relatively small radius of (Na, Al) atoms, the unit cell volume linearly decreases as jadeite component increases. In addition, the coupled substitution also stiffens the crystals. The bulk and shear modulus linearly increases as jadeite component increases.
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