corundum

Definitions

  • WordNet 3.6
    • n corundum very hard mineral used as an abrasive
    • ***
Webster's Revised Unabridged Dictionary
    • n Corundum (Min) The mineral alumina (Al2O3), as found native in a crystalline state. Transparent varieties are used as gemstones, including sapphire, which is the fine blue variety; the oriental ruby, or red sapphire; the oriental amethyst, or purple sapphire; and adamantine spar, the hair-brown variety. It is the hardest substance found native, next to the diamond.☞ The name corundum is sometimes restricted to the non-transparent or coarser kinds. Emery is a dark-colored granular variety, usually admixed with magnetic iron ore.
    • ***
Century Dictionary and Cyclopedia
    • n corundum Alumina, or the oxid of the metal aluminium, as found native in a crystalline state. It crystallizes in the rhombohedral system, often appearing in tapering hexagonal pyramids, and also occurs massive and granular. In hardness it is next to the diamond. Its specific gravity is about 4. In color it is blue, red, yellow, brown-gray, and white. The transparent varieties are prized as gems, the blue being the sapphire, the violet the Oriental amethyst, the red the ruby, and the yellow the Oriental topaz. Common corundum includes the opaque varieties and those of a dull, dark color. When pulverized it is used for grinding and polishing other gems, steel, etc. Emery is granular corundum, more or less impure, generally containing magnetic iron. The best sapphires, rubies, etc., come from Burma, India, China, and Ceylon; common corundum, from China, the Urals, New Jersey, Pennsylvania, and North and South Carolina; emery, from Asia Minor, the islands of Naxos and Samos near Ephesus in Asia Minor, and also from Chester in Massachusetts. Also called adamantine spar, diamond-spar.
    • ***
Chambers's Twentieth Century Dictionary
    • n Corundum ko-run′dum a mineral consisting of mere alumina, yet of great specific gravity—about four times that of water—and second in hardness only to the diamond.
    • ***

Etymology

Webster's Revised Unabridged Dictionary
From Hind. kurand, corundum stone
Chambers's Twentieth Century Dictionary
Hind. kurund.

Usage

In literature:

The corundum burr in McTeague's engine hummed in a prolonged monotone.
"McTeague" by Frank Norris
Silex Corundum made a motion as of some body flying through space, and looked inquiringly at the travelers.
"Through Space to Mars" by Roy Rockwood
Corundum and pure emery are ores that are very rich in aluminum, containing about fifty-four per cent.
"Scientific American Supplement, Vol. XXI., No. 531, March 6, 1886" by Various
There is no known substance, not even corundum, hard enough to resist the swift impact of myriads of little stones.
"Among the Forces" by Henry White Warren
I carried the specimen of corundum in my waistcoat pocket.
"The Hand in the Dark" by Arthur J. Rees
And I should not be surprised if corundum could be found in those rocks back of the house.
"Lippincott's Magazine, Vol. 22, September, 1878" by Various
This is true whether it has reference to a grindstone, emery, corundum wheel, or a plain oil stone.
"Practical Mechanics for Boys" by J. S. Zerbe
The surfaces of crystals of corundum are often clouded or dull, whilst its classification of lustre is vitreous.
"The Chemistry, Properties and Tests of Precious Stones" by John Mastin
Pliny says, corundum was used in the form of a splinter fixed in an iron style.
"Scarabs" by Isaac Myer
Certain minerals, such as magnetite, ilmenite, spinel, corundum, etc., are often found as primary segregations within the mass of igneous rock.
"The Economic Aspect of Geology" by C. K. Leith
Thus they called blue corundum gems blue rubies; yellow corundums, yellow rubies, etc.
"A Text-Book of Precious Stones for Jewelers and the Gem-Loving Public" by Frank Bertram Wade
The corundum, mica, talc, and monazite are, I believe, unexcelled in the United States.
"Our Southern Highlanders" by Horace Kephart
The term corundum is often restricted to the remaining kinds, i.e.
"Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 4" by Various
ADAMAN'TINE SPAR, a name of the mineral corundum or of a brownish variety of it.
"The New Gresham Encyclopedia. Vol. 1 Part 1" by Various
The stone known as "Oriental emerald" is a green corundum.
"Encyclopaedia Britannica, 11th Edition, Volume 9, Slice 3" by Various
The Eastern nations have used corundum for this purpose for ages.
"Inventions in the Century" by William Henry Doolittle
Haematite crystallizes in the rhombohedral system, and is isomorphous with corundum (Al2O3).
"Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 7" by Various
For figures of other combinations see CALCITE and CORUNDUM.
"Encyclopaedia Britannica, 11th Edition, Volume 7, Slice 7" by Various
Copper ore is found in many tracts throughout India, plumbago in Madras, and corundum in southern India.
"Encyclopaedia Britannica, 11th Edition, Volume 14, Slice 4" by Various
Iron is found and smelted at the foot of the hills, and corundum exists in certain localities.
"Encyclopaedia Britannica, 11th Edition, Volume 15, Slice 6" by Various
***

In science:

Dust grains composed of Fe, Si, Mg, and Al in form of metallic iron, enstatite (MgSiO3 ), and corundum (Al2O3 ) are considered as sources of dust opacity.
A comparison of chemistry and dust cloud formation in ultracool dwarf model atmospheres
The most refractory cloud condensate layer in Marley, Ackerman & Lodders-models is composed of corundum or Ca-Aluminates which serve as element sinks, hence, not depicted in Fig. 3.
A comparison of chemistry and dust cloud formation in ultracool dwarf model atmospheres
In the ‘mixed’ case, there is no layer where C is more abundant than O, then, only silicate, troilite, and corundum grains can be formed.
The origin of dust in galaxies revisited: the mechanism determining dust content
The abundant presolar minerals in primitive meteorites are diamond, SiC, graphite, corundum, spinel, and silicates; less frequently found are Si3N4, hibonite, and TiO2 (Table 3). Presolar graphite grains also often enclose small trace element carbide and Fe-Ni metal particles.
Presolar grains from meteorites: Remnants from the early times of the solar system
Schmid-Burgk and Scholz (1981) already discussed Al2O3 formation in Mgiants and an emission feature at 13 µm, present in 40-50% of all O-rich AGB stars (Sloan et al. 1996), was identified as corundum (Onaka et al. 1989, Begemann et al. 1997, Kozasa and Sogawa 1997, Fabian et al. 2001).
Presolar grains from meteorites: Remnants from the early times of the solar system
Astrophys. J. 510, 999-1010. Choi, B.-G., Huss, G.R., Wasserburg, G.J., Gallino, R., 1998. Presolar corundum and spinel in ordinary chondrites: Origins from AGB stars and a supernova.
Presolar grains from meteorites: Remnants from the early times of the solar system
Choi, B.G., Wasserburg, G.J., Huss, G.R., 1999. Circumstellar hibonite and corundum and nucleosynthesis in asymptotic giant branch stars.
Presolar grains from meteorites: Remnants from the early times of the solar system
Acta, 67, 4823-4848. Hutcheon, I.D., Huss, G.R., Fahey, A.J., Wasserburg, G.J., 1994. Extreme 26Mg and 17O enrichments in an Orgueil corundum: Identification of a presolar oxide grain.
Presolar grains from meteorites: Remnants from the early times of the solar system
Astrophys. J. 454, L157-L160. Nagashima, K., Krot, A.N., Yurimoto, H., 2004. Stardust silicates from primitive meteorites. Nature 428, 921-924. Nguyen, A., Zinner, E., Lewis, R.S., 2003. Identification of small presolar spinel and corundum grains by isotopic raster imaging.
Presolar grains from meteorites: Remnants from the early times of the solar system
***