142 



Globular, 41. 

 Goniometers, 12. 

 Granular, 40. 

 Greasy luster, 43. 



Habit of crystals, 38. 



Haloids, 63-66. 



Hardness, definition, 42; scale of, 



42-43. 

 Heini prism, 37. 

 pyramid. 36. 

 Hemimorpbic group, 29. 34. 

 Hexagonal crystals, optical charac- 

 ters, 25. 

 Hexagonal prisms. 26. 



pyramids, 26. 

 Hexagonal system, 25-31; axes, 25; 

 hexagonal division: 25-27; nor- 

 mal group, 25-27; pyramidal 

 group, 27; 

 rhombohedral division: 27-31; 

 rhombohedral group, 27-29; 

 rhombohed ral-hemimorphic 

 group, 29; trirhombohedral 

 group, 29; trapezohedral 

 group, 30. 

 Hexagonal symmetry, 10. 

 Hexahedron, see Cube. 

 Hexakistetrakedron, 19. 

 Hexoctahedron, 14. 

 Hydrocarbon compounds, 129-31. 

 Hydrous silicates, 10S-15. 



Ideal forms, 13. 



Inclusions, 40. 



Indexes, 11. 



Intercepts, 11. 



Interchangeable axes, 10. 



Interference phenomena, see Optical 



characteristics. 

 Iodids, 63-66. 

 Isometric crystals, 13. 

 Isometric system, 13-19; symmetry 



of, 13; normal group, 13-16; pyri- 



tohedral group, 16-18; tetrahedral 



group, 18-19. 

 Isomorphism, 45-46. 

 Isomorphous groups, 46. 



NEW YORK STATE MUSEUM 



Lamellar, 40. 



Law of constancy of interfacial 

 angles, 6-7; of, symmetry, 7-10; of 

 simple mathematical ratio, 11-12. 



Laws of crystals, 6-12. 



Left-handed crystals, 30. 



Luster, 43. 



Macro axis, 31. 

 dome, 33. 

 pinacoid. 32. 

 prism, 32. 

 pyramid, 33. 

 Mammillary, 41. 

 Massive, 6. ^ 



Metallic luster. 43. 

 Metals, 49-51. 

 Metasilicates, 91-97. 

 Meteorites, 131. 

 Micaceous, 40. 

 Microscope, polarizing, 12. 

 Mineral, artificial, 4; definition of, 



4. 

 Mineral collection of New York 



state museum, 136-38. 

 Mineral kingdom, 4. 

 Mineralogy, science of, 4. 

 Models of crystals, 7. See also 



cover envelope. 

 Molecules, 5. 

 Molybdates, 128-29. 

 Monoclinic crystals, 34. 

 Monoclinic system, 34-36; normal 



group, 34-36. 



Native elements, 47. 

 Niobates, 116-17. 

 Nonmetallic luster, 44. 

 Nonmetals, 47-48. 



Normal groups, 13-16, 20-22, 25-26, 

 31-34. 34-36, 37-40. 



Octahedron, 14. 



Oolitic. 41. 



Optical characteristics, 13, 25, 37. 



Ortho axis, 31. 



dome, 33. 



pinacoid. 35. 



prism, 35. 



pyramid, 33. 







