• WordNet 3.6
    • n spinel a hard glassy mineral consisting of an oxide of magnesium and aluminum; occurs in various colors that are used as gemstones
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Webster's Revised Unabridged Dictionary
    • n Spinel (Min) A mineral occuring in octahedrons of great hardness and various colors, as red, green, blue, brown, and black, the red variety being the gem spinel ruby. It consist essentially of alumina and magnesia, but commonly contains iron and sometimes also chromium.☞ The spinel group includes spinel proper, also magnetite, chromite, franklinite, gahnite, etc., all of which may be regarded as composed of a sesquioxide and a protoxide in equal proportions.
    • n Spinel Bleached yarn in making the linen tape called inkle; unwrought inkle.
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Century Dictionary and Cyclopedia
    • n spinel A mineral of various shades of red, also blue, green, yellow, brown, and black, commonly occurring in isometric octahedrons. It has the hardness of topaz. Chemically, it consists of the oxids of magnesium and aluminium, with iron protoxid in some varieties, also chromium in the variety picotite. Clear and finely colored red varieties are highly prized as ornamental stones in jewelry. The red varieties are known as spinel ruby or balas ruby, while those of a dark-green, brown, or black color, containing iron protoxid in considerable amount, are called ceylonite or pleonaste. The valuable varieties, including the spinel ruby (see ruby), occur as rolled pebbles in river-channels in Ceylon, Burma, and Siam; they are often associated with the true ruby (corundum). The spinel group of minerals includes several species which may be considered as made up of equal parts of a protoxid and a sesquioxid (RO + R2O3). Here belong gahnite, magnetite, franklinite, etc. An octahedral habit characterizes them all.
    • n spinel A bleached yarn from which the linen tape called inkle is made.
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Chambers's Twentieth Century Dictionary
    • n Spinel spin′el or spi-nel′ a mineral composed chiefly of magnesia and alumina, and crystallising in octahedra—ruby, or magnesia spinel, reddish; pleonaste, dark green to black; picotite, or chrome spinel, black; gahnite, or zinc spinel, green to brown; hercynite, or iron spinel, black.
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Webster's Revised Unabridged Dictionary
F. spinelle, or LL. spinellus, perhaps from L. spina, a thorn, a prickle, in allusion to its pointed crystals
Chambers's Twentieth Century Dictionary
Low L. spinellus, dim. of spina, a thorn.


In literature:

From certain indications I judged these stones, which might have been spinels or carbuncles, or even rubies, to be very ancient.
"The Ivory Child" by H. Rider Haggard
They were true rubies, not spinels, remember that.
"My Strangest Case" by Guy Boothby
He is also lord of the mines of rubies, sapphires, and spinels.
"A General History and Collection of Voyages and Travels, Volume VII" by Robert Kerr
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 spinel is of about the same hardness as topaz and hence is usually rated as 8 in hardness.
"A Text-Book of Precious Stones for Jewelers and the Gem-Loving Public" by Frank Bertram Wade
Along the rim played the fires of the spinel.
"A Republic Without a President and Other Stories" by Herbert Ward
Chrysoberyls have been found in New South Wales; spinel rubies in New South Wales and Victoria; and white topaz in all the states.
"Encyclopaedia Britannica, 11th Edition, Volume 2, Slice 8" by Various
Sapphires have been found in the west, and diamonds and spinels are reported from the northern mountains.
"The African Colony" by John Buchan
All the large historic stones which are called rubies are declared by Mr. King to be undoubted spinels.
"Stories about Famous Precious Stones" by Mrs Goddard Orpen
Then follows the topaz, which, with spinel and chrysoberyl, has a hardness of 8; whilst quartz falls a degree lower.
"Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 5" by Various

In science:

Previous studies indicate that the pyrochlores, like the spinels, are geometrically frustrated.
Route to Room-Temperature Superconductivity from a Practical Point of View
The effect of geometric frustration on the physical properties of spinel materials is drastic, resulting in, for example, heavy-fermion behavior in LiV2O4 .
Route to Room-Temperature Superconductivity from a Practical Point of View
Raman bands of the antiferromagnetic C o oxygen spinel clusters have not been observed.
Ferromagnetism in Co-doped ZnO films grown by molecular beam epitaxy: magnetic, electrical and microstructural studies
Hence one channel is non-conducting while the other is metallic, which has been dubbed “half metallic.” Many such ferromagnets (and ferrimagnets) have been predicted, particularly in the Heusler and half-Heusler compounds, but also in perovskites and spinels (Fe3O4).
Some Recent Issues in Quantum Magnetism
In order to test this hypothesis crystalline spinel ( f8 ) was used as an additional species.
Fitting of dust spectra with genetic algorithms - I. Perspectives & Limitations