lO WILLCOX : 



There are many varieties of feldspar. The soda feldspar 

 is called albite, and the chief portion of the soda on earth and 

 in the seas has been derived from the decomposition of albite. 



The moonstone, found in Ceylon, is a variety of feldspar. 



The green amazon stone found near Pike's Peak, in Colo- 

 rado, is a variety of feldspar. A transparent variety, con- 

 sisting of a few specimens only, has been found in a mica 

 mine in Mitchell County, North Carolina. A varietj^ called 

 Labradorite is found in Labrador. It is highly opalescent, 

 like moonstone, but it reflects several beautiful colors. 



Hornblende is an abundant mineral, composed of silica, 

 alumina, lime, magnesia and iron. There are many varieties, 

 differing somewhat in composition. The purest form of it is 

 in diopside, found in Jefferson County, New York. 



Mica, or isinglass, is a mineral not differing much in com- 

 position from feldspar. It is used chiefly in the doors of stoves, 

 lyike feldspar, it forms a fertile soil when decomposed. 



Granite is composed of feldspar, quartz and mica. In 

 some granites the mica is replaced with hornblende. This 

 variety is termed s^'enite. 



The red color in some granites is due to an excess of iron 

 in the feldspar, especially in the granite from Nova Scotia. 



A few of the substances composing the common minerals 

 serve as an important and even a vital factor in the animal 

 and vegetable economy in promoting the growth of all the 

 vegetable kingdom ; and inasmuch as no animal life can 

 subsist without vegetable life, all created living beings are 

 dependent on a few mineral substances for their existence on 

 the earth. 



The elements or substances necessary for plant growth are 

 oxygen, carbon, hydrogen, nitrogen, lime, potash, iron, phos- 

 phorus, soda and sulphur, with small ]-)ro]K)rtions of several 

 others . 



The four first mentioned are found in the air, and all the 

 others exist in the soil, having been deconijiosed and released 



