Coral fishing-vessels leave Italy the beginning of March and return from the African coast in October; at one time as many as four hundred vessels were engaged in this industry. TABLE OF HARDNESS AND SPECIFIC GRAVITY. ────────────────────┬───────────┬────────────── │ HARDNESS. │ SPECIFIC │ │ GRAVITY. ────────────────────┼───────────┼────────────── Achroite │ 7. — 7.5 │ 3. — 3.1 Alexandrite │ 8.5 │ 3.65 — 3.8 Almandine │ 7.5 │ 4. — 4.2 Almandite │ 7.5 │ 4. — 4.2 Amber │ 2. — 2.5 │ 1.065 — 1.08 Apatite │ 4.5 — 5. │ 2.95 — 3.25 Axinite │ 6.5 — 7. │ 3. — 3.3 Beryl │ 7.5 — 8. │ 2.67 — 2.73 Bobrowska garnet │ 6. │ 3.85 Bohemian " │ 7.5 │ 3.69 — 3.78 Brazilian emerald │ 7. — 7.5 │ 3. — 3.1 " sapphire │ 7. — 7.5 │ 3. — 3.1 Cachelong │ 5.5 — 6. │ 2. — 2.1 Cat’s-eye │ 8.5 │ 3. — 3.8 Ceylon chrysolite │ 7. — 7.5 │ 3. — 3.1 " peridot │ 7. — 7.5 │ 3. — 3.1 Chrysoberyl │ 8.5 │ 3.65 — 3.8 Chrysolite │ 6.5 — 7. │ 3.3 — 3.5 Chrysoprase │ 7. │ 2.56 Cinnamon stone │ 6.5 │ 3.5 — 3.56 Cyanite │ 5. — 7. │ 3.45 — 3.7 Cymophane │ 8.5 │ 3.65 — 3.8 Demantoide │ 6. │ 3.85 Diamond │10. │ 3.5 — 3.6 Dichroite │ 7. — 7.5 │ 2.56 — 2.67 Diopside │ 5. — 6. │ 2.9 — 3.5 Emerald │ 7.5 — 8. │ 2.67 — 2.73 Epidote │ 6. — 7. │ 3.32 — 3.50 Essonite │ 6.5 │ 3.5 — 3.56 Euclase │ 7.5 │ 3.1 Fluor spar │ 4. │ 3.1 — 3.2 Garnet │ 5. — 8. │ 3.15 — 4.3 Grossularite │ 6.5 │ 3.5 — 3.56 Hematite │ 5.6 — 6.5 │ 4.2 — 5.3 Hiddenite │ 6.5 — 7. │ 3.13 — 3.19 Hyacinth │ 7.5 │ 4.4 — 4.7 Hydrophane │ 5.5 — 6. │ 2. — 2.1 Hypersthene │ 6. │ 3.3 — 3.4 Idocrase │ 6.5 │ 3.35 — 3.45 Indicolite │ 7. — 7.5 │ 3. — 3.1 Jacinth │ 7.5 │ 4.4 — 4.7 Jargoon │ 7.5 │ 4.4 — 4.7 Jasper │ 7. │ 2.31 — 2.67 Jet │ 2.5 │ 1.35 Labrador │ 6. │ 2.62 — 2.76 " hornblende │ 6. │ 3.3 — 3.4 Lapis lazuli │ 5. — 5.5 │ 2.38 — 2.42 Malachite │ 3.5 — 4. │ 3.6 — 4. Moonstone │ 6. — 6.5 │ 2.4 — 2.6 Obsidian │ 6. — 7. │ 2.25 — 2.8 Olivine │ 6.5 — 7. │ 3.3 — 3.5 Opal │ 5.5 — 6. │ 2.