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Zircon appears to have been first discovered by Klaproth in 1789, in the form of an earth, and six years later he found that the stone hyacinth contained a similar substance, both having the formula, ZrSiO4, and both having as their colouring agent ferric oxide. There are several methods of obtaining the metallic element, [...] The beryl is a compound of silicates of beryllia and alumina, with the formula 3BeOSiO2 + Al2O3,3SiO2, or 3BeO,Al2O3,6SiO2. It differs very little indeed from the emerald, with the exception of its colour. In the ordinary varieties this is somewhat poor, being mostly blue, or a dirty or a greenish yellow; the better kinds, [...] |
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