TABLE I
Chemical Composition of Gem-Stones
| (a) Elements— | ||
| Diamond | C | |
| (b) Oxides— | ||
| Corundum | Al2O3 | |
| Quartz | SiO2 | |
| Chalcedony | SiO2 | |
| Opal | SiO2.nH2O | |
| (c) Aluminates— | ||
| Spinel | MgAl2O4 | |
| Chrysoberyl | BeAl2O4 | |
| (d) Silicates— | ||
| Phenakite | Be2SiO4 | |
| Dioptase | H2CuSiO4 | |
| Peridot | Mg2SiO4 | |
| Zircon | ZrSiO4 | |
| Enstatite | MgSiO3 | |
| Diopside | CaMg(SiO3)2 | |
| Nephrite | CaMg3(SiO3)4 | |
| Sphene | CaTiSiO5 | |
| Benitoite | BaTiSi3O9 | |
| Andalusite | Al(AlO)SiO4 | |
| Kyanite | (AlO)2SiO3 | |
| Topaz | [Al(F,OH)]2SiO4 | |
| Epidote | Ca2(Al,Fe)2(AlOH)(SiO4)3 | |
| Euclase | Be(AlOH)SiO4 | |
| Prehnite | H2Ca2Al2(SiO4)3 | |
| Iolite | H2(Mg,Fe)4Al8Si10O37 | |
Garnet { | Hessonite | Ca3Al2(SiO4)3 |
| Pyrope | Mg3Al2(SiO4)3 | |
| Almandine | Fe3Al2(SiO4)3 | |
| Andradite | Ca3Fe2(SiO4)3 | |
| Beryl | Be3Al2(SiO3)6 | |
| Spodumene | LiAl(SiO3)2 | |
| Jadeite | NaAl(SiO3)2 | |
| Moonstone | KAlSi3O8 | |
| Tourmaline | 12SiO2.3B2O3.(9-x)[(Al,Fe)2O3].3x[(Fe, | |
| Axinite | HCa3Al2B(SiO4)4 | |
| Idocrase | (Ca,Mn,Mg,Fe)2(Al,Fe)(OH,F)]Si2O7 | |
| (e) Phosphates— | ||
| Beryllonite | NaBePO4 | |
| Apatite | Ca5(F,Cl)(PO4)3 | |
| Turquoise | CuOH.6[Al(OH)2].H5.(PO4)4 | |