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All precious stones are transparent, or at least translucent, from which it may be concluded that the matter of which each consists is homogeneous. Now this homogeneity could never have been attained by the mixture of their elements in the solid state, however finely these may have been pulverized, and hence they must have [...] Thomas de Cantimpré tells us that the beryl cures quinsy and swollen glands in the neck if the affected part be rubbed with the stone. It is also useful as a remedy for diseases of the eye, and if water in which it has been steeped be given to anyone suffering from an attack of [...] The turquoise is a pseudomorph. In colour it is blue or greenish-blue, sometimes opaque, varying between that and feeble translucency, though it should be said that in all forms, even those considered opaque, a thin cutting of the stone appears almost transparent, so that the usual classing of it among the opaque stones must be [...] In the dichroscope the ruby shows two images, one square of a violet red, the second square being a truer and a paler red. It may be subjected to strong heat, when it changes its colour to a sooty or dirty slate, this varying with the locality in which the stone is found, and the [...] The fixing of the specific gravity of a stone also determines its group position with regard to weight; its colour and other characteristics defining the actual stone. This is a safe and very common method of proving a stone, since its specific gravity does not vary more than a point or so in different [...] |
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