What do kyanite andalusite and sillimanite have in common?

What do kyanite andalusite and sillimanite have in common?

Kyanite, andalusite, and sillimanite are naturally occurring anhydrous aluminum silicate minerals. Each has the same chemical formula, Al2SiO5, but differing crystal structures, making them mineral polymorphs. Andalusite also occurs in placer concentrations where it has weathered out of rock.

What is the formula for kyanite?

Al 2SiO 5

Formula (repeating unit) Al 2SiO 5
Strunz classification 9.AF.15
Crystal system Triclinic
Crystal class Pinacoidal (1) (same H-M symbol)

Which refractory is formed when kyanite and sillimanite are heated?

They confirmed earlier observations that heating the sillimanite composition produces mullite plus glass or silica. Indeed, Bragg and Claringbull claim that both sillimanite and andalusite transform to mullite and silica when heated. Kyanite also transforms to mullite and silica when heated in the range 1350°–1380°C.

How do you differentiate kyanite and sillimanite?

Kyanite is the high-pressure structure of the three, while sillimanite is the high-temperature structure. Andalusite occurs at lower pressures and temperatures.

What is mullite and andalusite?

Introduction. As a member of the alumino-silicate minerals, andalusite (Al2O3·SiO2) can be applied in the production of commercial refractories with high content of mullite. Mullite is a solid solution that the Al2O3 to SiO2 mole ratio is in the range of 3:2 to 2:1.

Is kyanite man made?

Thankfully, there aren’t any synthetic kyanite products on the market today save for things like blue glass or blue quartz. 7. Who should wear Kyanite?

What does sillimanite look like?

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).

What is sillimanite refractory?

Sillimanite brick is a kind of refractory which is made by silimanite and other minerals. Sillimanite brick is a kind of high grade refractory mineral, it has the characteristics of low thermal expansion rate, resistance to metallurgical slag and various glass liquid, good wear resistance of high temperature.

What grade of metamorphism is sillimanite?

Sillimanite from a variety of high-grade metamorphic rocks contains from 0-13 to 1-82 weight per cent Fe2O3 and less than 0-1 weight per cent TiO2. The iron is trivalent and substitutes for Al only.