Carbuncle is a beautiful gem of a deep red colour (with a mixture of scarlet) . It was called by the Greeks anthrax and is found in the East Indies. When held up to the sun, it loses its deep tinge, and becomes of the colour of burning coal. The name belongs for the most part to rubysapphire, though it has been also given to red spinel and garnet. Research Carbuncle
Emery is an impure fine-grained form of corundum (aluminiumoxide) of blackish or bluish-grey colour, chiefly found in shapeless masses and mixed with other minerals.in conjunction with iron oxides and spinel. Emery is very hard; is infusible, and is not attacked by acids; has the formulae Al2O3 employed widely as an abrasive: it is employed in cutting and polishing precious stones; in smoothing the surface of the finer kinds of lenses preparatory to their being polished; in the polishing of marble; by cutlers, locksmiths, glaziers, and other artisans. For all these purposes it is pulverized in large iron mortars or in steelmills, and the powder, which is rough and sharp, is carefully washed and sifted into eight or ten different degrees of fineness. Emery-paper and emery-cloth are made by laying a thin coat of glue upon the fabric, and dusting the emery from a sieve of the required size. Typically emery consists of 60 percent corundum and 40 percent iron oxide in the form of magnetite. Research Emery
Gadolinite, named after the Russian chemist Gadolin, or ytterbite is a naturally occurring complex silicate containing beryllium, iron and many of the rare earth metals, of which the latter is an important source. The principal rare earths that occur in gadolinite are yttrium and erbium, together with smaller amounts of cerium and lanthanum.It is usually found in dull, amorphous masses disseminated through granite; is black, or very dark green in colour, with a resinouslustre. *Gahnite
Gahnite (zinc spinel) is a dark green mineral of the spinel group consisting of zincaluminiumoxide. It is named after J G Gahn the Swedish chemist. Research Gadolinite
Spinel is a common metamorphic mineral occurring imbedded in crystalline limestone, gneisses, and serpentine. Spinel occurs as a common accessory mineral in many dark igneous rocks. When transparent and finely coloured it is often confused for ruby and is used as a gem stone. An oxide of magnesium and aluminium it has the formulae MgAl2O4 and a relative hardness of 8. Research Spinel
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Balas Ruby
