Dunilite

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Dunilite is a rare olivine group mineral with the corresponding chemical formula Magnesium, Iron, Manganese, Silicate (Mg,Fe,Mn)2SiO4. Long mistaken for green peridot, dunilite was identified in 2000 as a new gem variety from the olivine group. Dunilite- Discovered by Mr. Dunil Palitha Gunasekera in 1996.

Dunil Palitha Gunasekera Dip. Gem, FGA,- President Crystals Gallery -Gem Lab

Dunilite occurs in only one locality called, “Katukubura mountain” Kolonne, Sri Lanka. Dunilite can be found in colours light greenish-yellow to brownish green, the depth of colour being related to the iron content of the stone.

• Group: Olivine
• Crystal System: Orthorhombic
• Lustre: Vitreous
• Fluorescence: None
• Hardness: 6 1/2
• Fracture: Uneven
• Cleavage: None
• Specific Gravity: 3.48
• Optic Sign: Biaxial (-)
• Dispersion: 0.020
• Transparency: Transparent to translucent
• Habit: Tabular, rectangle shaped aggregate crystals.

• Refractive Index: a= 1.677, B=1.700, y=1.718 ( The refractive indices of dunilite are higher than peridot and sinhalite )

Similarly looks with Faceted Stones:Yellow chrysoberyl, Sinhalite
Tenacity:Brittle
Might be confused with:Peridot, Forsterite, Sinhalite
Birefringence : 0.041
Density:3.48(g/cm3)
Radioactivity:Not Radioactive
Dispersion:Relatively Weak
Pleochroism:Strong : Brownish Yellow/ Greenish Yellow
Usual Sizes:0.05 to 1 carat
Occurrence:In a huge calcite rock with black amphibole rocks


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