Monochromatic light, 35, 36, 59-60.
Monoclinic system, 14, 15.
Moonstone, 17, 42, 55, 109, 157.
Morganite, 123.
Moss agate, 16.
Mountings, metals used for, 65.
Mudda, 78.
Mya Yay or Yay kagauk, 147.
Nephrite or Jade—introduction and physical properties, 146-147;
uses, 147; grades, 147-148; occurrences, 148-149; mining, 150;
jade
cutting industry, 150-151; jadeite trade, 151-152. New Jagersfontein,
83. Nizam diamond, 97. Noble, Sir Arthur, 59. Non-metallic lustre, 17.
O
Obsidian, 6.
Octahedron, 13, 67, 86.
Odontolite, 153.
Olivine, 14, 120, 139.
Olivine or peridote, introduction and physical properties, 139;
uses, 139. Onyx, 143, 144.
Opal, 4, 6, 11, 17, 18, 19, 41, 145, 146; Hungarian, 8. Opalescence, 17.
Optical
groups—isotropic, anisotropic, uniaxial, biaxial, 38. Optical
properties, 29-40. Ordinary ray, 37, 40. Oriental topaz, 127. Orlofi or
Amsterdam diamond, 96-97. Orthorhombic system, 14, 15. Oxides and
hydroxides, 11. Oxygen, 10.
P
Padmaraga, 101, 104, 105.
Panna State, 47, 78, 79, 84, 92.
Pantha, 148.
Parallel groups, 16.
Parting, 22.
Peace ruby, 111, 115-116.
183
