Spinel
Spinel , noun
[French spinelle, or Late Latin spinellus, perhaps from Latin spina a thorn, a prickle, in allusion to its pointed crystals.]
(Mineralogy) A mineral occurring 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.
Also: Spinelle
Spinel , noun
Bleached yarn in making the linen tape called inkle; unwrought inkle. — Knight