Fibrolite is an aluminosilicate mineral with the chemical formula Al2SiO5. Fibrolite is a fibres form 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 : colourless 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 glassindustries. Sillimanite is the best raw material for the manufacture of high aluminarefractories or 55-60% alumina bricks.