from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A mineral, aluminum silicate (Al2SiO5), usually found in orthorhombic crystals of various colors.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An aluminium nesosilicate mineral, Al2SiO5.
from the GNU version of the Collaborative International Dictionary of English
- n. A silicate of aluminium, occurring usually in thick rhombic prisms, nearly square, of a grayish or pale reddish tint. It was first discovered in Andalusia, Spain.
from The Century Dictionary and Cyclopedia
- n. A mineral of a gray, green, bluish, flesh, or rose-red color, consisting of anhydrous silicate of aluminium, sometimes found crystallized in four-sided rhombic prisms.
Relative to one another, kyanite forms in a lower temperature/higher pressure environment; andalusite forms in a lower temperature/lower pressure environment, and sillimanite forms in a higher temperature/higher pressure environment.
South Africa supplies most of the andalusite imported for industrial consumption in the United States.
France and India also produce andalusite and kyanite, respectively.
Kyanite and its related mineral “cousins,” sillimanite and andalusite, are called polymorphs.
"The quartzite shows granoblastic and blastopsammitic texture, with grain sizes varying from coarse sand to very fine pebble and with minor microcrystals of sericite, fuchsite, andalusite and iron oxide, besides detrital tourmaline, rutile, and zircon." link
Alluvial diamonds, uranium, lime, andalusite and platinum occur in abundance.
The local and export sales of industrial minerals revealed variable trends, with export revenues from the sale of vermiculite and granite declining considerably, and those for andalusite and phosphate rock increasing.
Local and export sales of industrial minerals showed variable trends, with export revenues from the sale of vermiculite and granite declining considerably, and those for andalusite and phosphate rock increasing.
Silimanite is found mainly in India while andalusite and kyanite are more widespread.
The three materials are rather similar except that silimanite and andalusite can be used raw while kyanite needs to be calcinated above 1350°C at which temperature it expands by 17%.