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Al2SiO5 A brown, pale-green, or white neosilicate mineral with vitreous luster crystallizing in the orthorhombic system; commonly occurs in slender crystals, often in fibrous aggregates; hardness is 6-7 on Mohs scale, and specific gravity is 3.23. Also known as fibrolite.



a mineral of the silicate class. Sillimanite is a high-temperature, polymorphic modification of the composition Al[AlSiO5] and contains 1–1.5 percent Fe2O3 in admixture form. The sillimanite structure is made up of chains of alternating SiO4 and AlO4 tetrahedrons, connected by chains of Al octahedrons. The mineral crystallizes in the orthorhombic system, forming acicular crystals, compact radiated masses, or thin fibrous aggregates. It sometimes forms dispersed, filiform inclusions in other minerals (fibrolite variety). Sillimanite is gray, light brown, or pale green; it has a vitreous luster, a hardness of 6.5-7.5 on Mohs’ scale, and a density of 3,270 kg/m3. At high temperatures (approximately 1545°C), it decomposes into mullite and silica.

Sillimanite occurs in thermally and regionally metamorphosed clay rocks. It serves as a raw material in the production of refractories and acid-resistant products with a high alumina content. The largest known sillimanite deposits are in India (Khasi Hills and Pipri).


Kostov, 1. Mineralogiia. Moscow, 1971. (Translated from English.)
References in periodicals archive ?
gr) was used to assess the sillimanite content in the total heavy minerals.
Widespread garnet and cordierite in these rocks formed by breakdown of biotite and sillimanite, which indicates prograde metamorphism.
In this study we compared the relationship between heavy mineral assemblages typical of the Baltic Shield (apatite, amphiboles, pyroxenes, zircon, garnet, epidote, tourmaline, staurolite, sphene, corundum, sillimanite, monazite, magnetite, and ilmenite) and the local bedrock (hematite, leucoxene, pyrite, micas, limonite, phosphates, carbonates, anatase, barite, and chlorite) (Jouzapavicius 1976; Viiding 1976).
Tenders are invited for sillimanite (unsorted chilly al203 content 40 -45 percent)
Within the drill logs high grade metamorphic minerals such as sillimanite and cordierite as well as zone of migmatite provide encouragement for graphitic flake development.
The Rubicon drill hole is currently 1956 metres below surface and has intersected 123 metres (core length) of permissive schist units which are characterized by significant alumina- and potassium-rich minerals (white feldspar, sillimanite, garnet, sericite and biotite), variable amounts of pyrite and pyrrhotite (trace to 5%) and local sphalerite and galena (trace to 3%).
Tenders are invited for Supply of 1760 Tons Of Sillimanite For Sru Ifico
Some of unique gemstones to be showcased include the rare Green Sillimanite and Mint Green Fluorite.
Paul Maton of the Sillimanite Group spoke on geodetics; Dr.
Tenders are invited for job of transportation of llmenite or any other co-product of llmenite (like Rutile, Zircon, Garnet, Sillimanite, etc.