Opal 2·15 Moonstone 2·57 Iolite 2·63 Quartz 2·66 Beryl 2·74 Turquoise 2·82 Beryllonite 2·84 Phenakite 2·99 Euclase 3·07 Tourmaline 3·10 Enstatite 3·10 Andalusite 3·18 Spodumene 3·18 Apatite 3·20 Axinite 3·28 Diopside 3·29 Epidote 3·37 Peridot 3·40 Idocrase 3·40 Sphene 3·40 Diamond 3·52 Topaz 3·53 Spinel 3·60 Kyanite 3·61 Garnet (Hessonite) 3·61 Benitoite 3·64 Chrysoberyl 3·73 Garnet (Pyrope) 3·78 Garnet (Demantoid) 3·84 Corundum 4·03 Garnet (Almandine) 4·05 Zircon (a) 4·20 Zircon (b) 4·69 TABLE VIII _Degrees of Hardness of Gem-Stones_ 5. Kyanite (5-7), apatite, lapis lazuli 5½. Enstatite, beryllonite, sphene 6. Opal, moonstone, turquoise, diopside 6½. Spodumene, peridot, garnet (demantoid), benitoite, idocrase, epidote, axinite, jade (nephrite) 7. Iolite, quartz, tourmaline, jade (jadeite) 7¼. Garnet (hessonite, pyrope) 7½. Beryl, garnet (almandine), zircon, phenakite, euclase, andalusite 8. Topaz, spinel 8½. Chrysoberyl 9. Corundum 10. Diamond TABLE IX.—DATA _Densities of Water and Toluol at Ordinary Temperatures_