andalusite

[ an-dl-oo-sahyt ]

noun

, Mineralogy.

1. an orthorhombic form of aluminum silicate, Al 2 SiO 5 , found in schistose rocks.

andalusite

/ ˌændəˈluːsaɪt /

noun

1. a grey, pink, or brown hard mineral consisting of aluminium silicate in orthorhombic crystalline form. It occurs in metamorphic rocks and is used as a refractory and as a gemstone. Formula: Al 2 SiO 5

andalusite

/ ăn′də-lo̅o̅′sīt′ /

1. A hard, grayish white to pinkish brown orthorhombic mineral. Andalusite occurs as nearly square prisms, often with cross-shaped cross sections, in metamorphic rocks. It is a polymorph of kyanite and sillimanite, but forms at shallower depths than they do, and at higher temperatures than kyanite and lower temperatures than sillimanite. Chemical formula: Al 2 SiO 5 .

Word History and Origins

Origin of andalusite¹

1830–40; named after Andalusia, where it was first found; -ite ¹

Example Sentences

In these biotite hornfelses the minerals, which consist of aluminium silicates, are commonly found; they are usually andalusite and 711 sillimanite, but kyanite appears also in hornfelses, especially in those which have a schistose character.

From Project Gutenberg

The andalusite may be pink and is then often pleochroic in thin sections, or it may be white with the cross-shaped dark enclosures of the matrix which are characteristic of chiastolite.

From Project Gutenberg

Among these may be mentioned cordierite and sillimanite gneisses, andalusite and kyanite mica schists, and those schistose calc silicate rocks which are known as cipolins.

From Project Gutenberg

Although for the most part the constituent grains are too small to be determined by the unaided eye, there are often larger crystals of garnet or andalusite scattered through the fine matrix, and these may become very prominent on the weathered faces of the rock.

From Project Gutenberg

It has the same percentage chemical composition as andalusite and sillimanite, but differs from these in its crystallographic and physical characters.

From Project Gutenberg