332 QUESTIONS. 



CHAPTER VII. 



56. What are most of the earthy minerals ? What is a silicate ? 

 What is said of the compound character of most earthy minerals ? 

 What are some of them which are very simple ? What proportion 

 does silica constitute of the earth's crust ? What is quartz ? What 

 is said of silica in mica and feldspar ? 



57. What are the properties of silica? What is said of its different 

 forms and conditions ? What of its being colored ? What is said of 

 flint ? What of the three varieties of quartz ? 



58. What is said of the crystals of quartz? What of rock .crystal? 

 What of the amethyst ? What of other crystals of quartz ? 



59. What is chalcedony ? What is said of the variety called car- 

 nelian? What of the agate? What of the onyx? What of the cat's 

 eye ? What is the composition of opal ? What is said of its varie- 

 ties ? What is said of silica in solution ? 



60. What are the two states in which silica exists? State in full 

 what is said of the changes from the one state into the other. Ex- 

 plain petrifaction with silica. 



61 . What is said of the silicates of magnesia ? What of the varie- 

 ties of talc ? What of serpentine ? What gave this name to it ? 

 What is verd antique ? What is said of chlorite ? 



62. What is said of pyroxene ? What of hornblende ? What of 

 its two remarkable varieties, asbestos and amianthus ? What is the 

 composition of alumina ? What is said of its base ? What is emery ? 



63. What is sapphire ? What is said of clay? What of the min- 

 eral called spinel? What of the silicates of alumina? What of feld- 

 spar ? What are its varieties in color and appearance ? 



64. What is kaolin ? What is said of albite ? What of labrador- 

 ite ? What is the composition of mica ? What are its qualities ? 

 What its uses ? 



65. What is said of garnet ? What of tourmaline ? What of the 

 composition of topaz ? What of its use in jewelry ? 



66. What is said of the composition of lapis lazuli ? What are 

 beryls and emeralds ? What is said of their size and their value ? 

 What of zircon ? 



CHAPTER VIII. 



76. What is the relation of mineralogy to geology ? What is the 

 derivation of the word geology ? In what senses does the geologist 

 use the term rock? How many elementary substances are there? 

 Name those which enter in any extent into the composition of the 

 rocks. What is said of the amount of oxygen in the earth's crust ? 



68. What is said of sulphur as a component of rocks ? What of 



