Search results
Results from the WOW.Com Content Network
Corundum is a crystalline form of aluminium oxide (Al 2 O 3) typically containing traces of iron, titanium, vanadium, and chromium. [ 3 ] [ 4 ] It is a rock -forming mineral . It is a naturally transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. [ 7 ]
Lustre (British English) or luster (American English; see spelling differences) is the way light interacts with the surface of a crystal, rock, or mineral. The word traces its origins back to the Latin lux , meaning "light", and generally implies radiance, gloss, or brilliance.
Adamantine spar is a silky brown variety of corundum. It has a hardness of 9 on the Mohs scale. [1] See also. Yogo sapphire; References This page was last edited ...
Because of corundum's hardness (pure corundum is defined to have 9.0 on the Mohs scale), it can scratch almost all other minerals. It is commonly used as an abrasive on sandpaper and on large tools used in machining metals, plastics, and wood.
Sapphires are a color variety of corundum, a crystalline form of aluminium oxide (Al 2 O 3). [14] Corundum is one of the hardest minerals, rating 9 on the Mohs scale. [15] Corundum gems of most colors are called sapphires, except for red ones, which are called rubies. [16] The term "Yogo sapphire" refers only to sapphires from the Yogo Gulch. [17]
The archetypal asteria is the star sapphire, generally corundum with near uniform impurities which is bluish-grey and milky or opalescent, which when lit has a star of six rays. In the red instance stellate reflection is rarer; the star- ruby occasionally found with the star-sapphire in Sri Lanka is among the most valued of "fancy stones".
It is commonly associated with olivine, magnetite, serpentine and corundum. [16] The vast Bushveld Igneous Complex of South Africa is a large layered mafic to ultramafic igneous body with some layers consisting of 90% chromite, forming the rare rock type chromitite (cf. chromite the mineral and chromitite, a rock containing chromite). [17]
Emery is a granular rock used to make an abrasive powder. It largely consists of corundum (aluminium oxide), mixed with other minerals such as the iron-bearing spinels, hercynite, and magnetite, and also rutile . Industrial emery may contain a variety of other minerals and synthetic compounds such as magnesia, mullite, and silica.