TABLE OF CONTENTS. 



I. Definition and properties of gem minerals 481 



Color 481 



Diaphaneity 482 



Luster ^. 482 



Refraction ^ 482 



Dispersion 484 



Polarization 484 



Pleochroism 484 



Phosphorescence 484 



Hardness 484 



Specific gravity 485 



Electricity 486 



Cleavage 486 



Fracture 486 



Form 487 



II. Description of )ninerals used as gems 487 



Albite: 



Aventurine — Moonstone — Peristerite 487 



Amber — Succinite 488 



Andalusite: 



Chiastolite— Made 488 



Anhydrite — V^ulpinite 489 



Apophyllite — Fish-eye stone 489 



Axinite 489 



Azurite and malachite 490 



Barite 490 



Beryl: 



Aquamarine — Emerald — Goshenite 490 



Beryilonite 491 



Brookite— Arkansite 492 



Carbonate of lime: 



Pearl — Coral — Marble — Calcite — Aragonite 492 



Cancrinite 494 



Cassiterite — Wood tin — Toad's-eye tin 494 



Catlinite — Pipestone 495 



Cat's-eye 495 



Chondrodite 495 



Chrysoberyl: 



Alexandrite — Cat's-eye — Cymophane 495 



Chrysocolla 496 



Coal — Jet — Cannel — Anthracite — Brown 496 



Cobaltite 497 



Corundum — Ruby — Sai)phire 497 



Crocidolite — Cat' s-ey e — Tiger' s-ey e 499 



475 



