Dunilite

-

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


Comments

Post a Comment

Popular posts from this blog

Natural Bi-Color Spinel Crystal Sri Lanka

-
Image
Natural Bi-Color Spinel Crystal Sri Lanka Ceylon Natural Bi-Color Spinel Crystal from Alluvial Gem Deposi t. It was bit deep color but, Inside Color is really nice. It is 5.05 Cts weight transported octahedron crystal from Rakwana, Sri Lanka. Spinel   is the magnesium-aluminum member of the larger spinel group of minerals with chemical formula MgAl₂O₄ . Spinel is actually a large group of minerals. Gahnite , hercynite , ceylonite , picotite , and galaxite are all part of the spinel group . This oxide mineral is a Cubic crystal system with 7.5–8.0 hardness according to the Mohs hardness scale.  Spinels   Specific Gravity is depending on the composition of chemicals such as Zn -rich spinel can be as high as 4.40, otherwise, it averages from 3.58 to 3.61. Spinel has many colors such as red, pink, blue, lavender/violet, dark green, brown, black, colorless, gray. Spinel is a single reflective Non-pleochroic gemstone and A...
Read more

Chrysoberyl

-
Image
The Gemstone Chrysoberyl is an aluminate of beryllium with the chemical formula BeAl₂O₄. The name chrysoberyl is derived from the Greek words "chrysos" and "beryllos". Its meaning is "a gold-white spar". It is known as a hard and durable gem after Sapphire. Chrysoberyl is an orthorhombic crystal mineral with 3.5 – 3.84 specific gravity and 8.5 hardness according to the more hardness scale. It is a Biaxial (+) mineral with refractive indexes nα=1.745 nβ=1.748 nγ=1.754. Chrysoberyl family Gemstones from old collection Chrysoberyl can be found colors such as green, yellow, brownish to greenish-black, colorless, pale shades of yellow, greenish Yellow, Yellowish Green, Honey Brown, Reddish Brown, Orangy yellow, Greenish Brown, Blue. Also, Golden Yellow Chrysoberyl is called "Ceylonese Chrysolite" as a trading name. Alexandrite Alexandrite cats eye The Chrysoberyl Alexandrite is a color change variety upon the ...
Read more