What does sillimanite mean?
What does sillimanite mean?
Definition of sillimanite : a brown, grayish, or pale green mineral that consists of an aluminum silicate in orthorhombic crystals often occurring in fibrous or columnar forms.
Does sillimanite have cleavage?
Sillimanite is named after the American chemist Benjamin Silliman (1779–1864). It was first described in 1824 for an occurrence in Chester, US….
| Sillimanite | |
|---|---|
| Crystal habit | Prismatic crystals, fibrous, acicular |
| Cleavage | {010} perfect |
| Fracture | Splintery |
| Tenacity | Tough |
How can you identify a sillimanite in a thin section?
Sillimanite thin section
- Formula: Al2SiO5
- System: Orthorhombic.
- Color: Colorless, white, etc.
- Lustre: Vitreous, Sub-Vitreous, Greasy.
- Hardness: 6½–7½
- Density: 3.23–3.27.
How is sillimanite formed?
Metamorphic rocks Disten or sillimanite, cordierite, and staurolite schists occur in conditions of high-degree metamorphism from pelite sediment, that is, shale, mudstone, and marl.
What are the uses of sillimanite?
Sillimanite minerals are mainly utilised in the production of mullite or high-alumina refractories. 95% of the world’s consumption of these minerals is used for this purpose in the manufacture of metals, glass, ceramics and cement.
What is sillimanite mineral?
sillimanite, also called Fibrolite, brown, pale green, or white glassy silicate mineral that often occurs in long, slender, needlelike crystals frequently found in fibrous aggregates. An aluminum silicate, Al2OSiO4, it occurs in high-temperature regionally metamorphosed clay-rich rocks (e.g., schists and gneisses).
Where is sillimanite found in Meghalaya?
Sonapahar area
The Precambrian terrain of the Meghalaya Plateau is characterised by the presence of a thin, long, discontinuous band of quartz-sillimanite schist which hosts the massive sillimanite-corundum deposits in the Sonapahar area.
Does sillimanite have twinning?
Sillimanite (also known as Fibrolite) is a polymorph with Andalusite and Kyanite….Sillimanite.
| Category: | Nesosilicate |
|---|---|
| Crystal Habit: | Crystals prismatic, may be acicular, with square cross sections, rounded and striated, poorly terminated, to 2 cm; as fibrous mats; rarely radiating. |
| Twinning: | None |
Where does sillimanite occur?
The finest light blue, transparent crystals are found in the gem sands of Sri Lanka and Burma. These stones are sometimes faceted and occasionally dyed red to simulate rubies. As sillimanite is normally found embedded in gneiss and schists, free-standing crystals are rare to non-existent.
Where is sillimanite found?
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. For detailed physical properties, see silicate mineral (table).