Fibrolite is a very interesting gemstone among gemstone families. Specially, Some gem cutters hate to cut. If You cut a Fibrolite, You must be a expert gem cutter. It can be seen cleavages perfect. Because of it’s structure It can be broken easily while cutting process and should be carefully in cutting process. But, You can use cabochon cut if it’s hard to use other faceting methods.
Colour: Greenish Yellow
Weight: 7.60 Cts
Dimension: 15.7 × 9.8 × 5.3 mm
Variety: Natural Yellow Fibrolite
Species: Natural Fibrolite
Origin: Sri Lanka 🇱🇰
Fibrolite is an aluminosilicate mineral with the chemical formula Al2SiO5. Fibrolite is fibrous form the gemstone variety of sillimanite. Although fibrolite has priority over sillimanite, the two species were not ultimately recognized as the same species until about 1854 by James Dwight Dana.
Mostly, It is found in colors such as colorless or white to grey, also brown, yellow, yellow-green, grey-green, blue-green and blue: colorless in thin section. Sometimes It has Sub Adamantine Luster. This Bi-Axial Mineral pleochroism is mostly Colourless to pale brown to yellow.
Natural sillimanite/fibrolite rocks cut into the required shape and size are used mainly in glass industries. Sillimanite is the best raw material for the manufacture of high alumina refractories or 55-60% alumina bricks.
• Refractive index: nα = 1.653 – 1.661
nβ = 1.654 – 1.670
nγ = 1.669 – 1.684
• Birefringence δ = 0.020 – 0.022
• Pleochroism: Colourless to pale brown to yellow
• Cleavage: perfect
• Fracture: Splintery
• Tenacity: Tough
• Mohs scale hardness: 7
• Luster: Vitreous to subadamantine, silky
• Streak: White
• Diaphaneity: Transparent to translucent
• Specific gravity: 3.24
• Optical properties: Biaxial (+)
• Crystal habit: Prismatic crystals, fibrous, acicular