Where is sillimanite formed?

Where is sillimanite formed?

Sillimanite is found at many points in France, Madagascar, and the eastern United States; a pale sapphire-blue gem variety occurs in the gravels of Sri Lanka.

Who discovered sillimanite?

Sillimanite was discovered by scientist Benjamin Silliman (December 4, 1816-January 14, 1885) and named for him in 1850. Silliman was a professor at Yale University and was instrumental in developing the university’s mineral collection.

What kind of rock is sillimanite?

metamorphic mineral
Introduction: sillimanite is a metamorphic mineral found in high-grade rocks (upper amphibolite/lower granulite facies) most typically in aluminium-rich pelites. Sillimanite has two polymorphs, kyanite and andalusite, which develop under conditions of lower temperature and different pressure to sillimanite.

Does sillimanite have high relief?

Sillimanite. Sillimanite is a metamorphic mineral found in high grade aluminous schists and gneisses. It is a polymorph of andalusite and kyanite, all having formula Al2SiO5. Keys to identification are high relief, needle-like, fibrous or bladed habit, characteristic square cross sections with one diagonal cleavage.

How does sillimanite occur?

Sillimanite occurs as a constituent of high-temperature metamorphosed rocks containing clay. In contact metamorphosed rocks it may occur in silimanite-cordierite gneisses or sillimanite-biotite horfels. In silica poor rocks, it may be associated with corundum.

What type of rock is sillimanite?

Introduction: sillimanite is a metamorphic mineral found in high-grade rocks (upper amphibolite/lower granulite facies) most typically in aluminium-rich pelites. Sillimanite has two polymorphs, kyanite and andalusite, which develop under conditions of lower temperature and different pressure to sillimanite.

Is sillimanite a gemstone?

Sillimanite (also known as Fibrolite) is found in various colours including green, yellow, brown, blue, white and even black. The gem is a complete Jekyll and Hyde; it can be discovered as a truly transparent gem, or completely opaque with a waxy lustre. …

Is Pleochroic a sillimanite?

Color/Pleochroism Vitreous luster and white streak.