The name Fibrolith refers to the fibrous form of Sillimanite. It is the rarest of the three trimorphs. One type of Sillimanite is called "Fibrolit". Sulillimanite is the official state mineral of Delaware. Sulillimanite, also called fibrolite, brown, light green or white vitreous silicate mineral, often found in long, slender, acicular crystals, often found in fibrous aggregates.


Sillimanite crystal from Burma, Sri Lanka and India is appreciated as important precious stone and sometimes polished into precious gems for gatherers. Sillimanite crystal from Mogok, Burma (Myanmar); and from the Ratnapura District, Sri Lanka.

In Orissa, India, another unusual spring of transparently crystallised sillimanite has been found. Sillimanite' fibrey mixes come from Brandywine Springs, New Castle Co. in Delaware; and darkbrown crystalline spray from Oconee Co. in South Carolina. Grey Sillimanite is found in Natrona Co. in Wyoming. Do you have a query about Sillimanit?

Mineral Sillimanite Data

Origin:Named after the US chemical scientist and mineralogen B. Silliman (1779-1824). Colour: Blueish, brownish-greenish, colourless, grey, grey-green. habit:Acicular - Appears as acicular crystal. Custom:Fibrous - Fiberrystals. Habite:Prismatic - Slim prism crystal (e.g. tourmaline). Heavy emulsion, r > v. Plekochroism (x): colourless, light bay or amber.

Pleochroism (y): colourless, greyish grey or greyish grey; Note: Sillimanite density = 3.24 g/cm3. 09.AF -Nesosilicates with extra ions; See also:Links to other data bases for Sillimanit : Search for Sillimanit with: Please pay a call on our advertisers for Sillimanite: Please ask here for Sillimanit: You can print or insert your Sillimanite sample label here:

SILLIMANIT ("aluminium silicate")

One type of Sillimanite is known as " Fibrolit ". It' a frequent filamentous solid shape. Sulillimanite is the Delaware state' s officially recognized minerals. The shine is flossy when it is filamentous or glassy. Clear crystal is clear to sheer. The crystal habits involve the use of unusual price specimens, but mostly filamentous materials. The hardness is 7.5 in large crystal, but the more filamentous shapes are more softened.

Remarkable deposits are Brazil, New England and many locations in Europe. The best field indicators are crystalline harbitus, colour, brittleness and firmness, if not fiber.


Sulillimanite, also known as fibrolite, a light-greenish, darker, darker, yellow or vitreous silica material, often found in long, slim, acicular crystal, often found in fiber form. Al2OSiO4, an aluminium siliceate, is found in high-temperature resistant, regional metamorphic clay-rich rock (e.g. slate and gneiss). Silimanite is found in many places in France, Madagascar and in the east of the United States; a light sapphire-blue type of gemstone is found in the gravel of Sri Lanka.

See Silikatmineral (table) for details of physic characteristics. Silimanite is polymorphic (with the same chemical but different crystalline structure) with cyanite and andalucite.

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