THE PHOSPHATES 131 



ignites easily, and burns with a yellow flame. On the opposite 

 page is given the composition of (I) a coking coal from the Con- 

 nelsville Basin of Pennsylvania, and (II) a cannel coal from 

 Kanawha County, "West Virginia.^ 



Anthracite Goal, — This is a deep black, lustrous, hard and 

 brittle variety, and represents the most highly metamorphosed 

 variety of the coal series. Such have been generally regarded 

 as bituminous coals from which a very large proportion of the 

 volatile constituents have been driven off by the agencies in- 

 volved in the production of mountain systems by the heat inci- 

 dent to the injection of igneous rocks, or through the oxidizing 

 influence of percolating water. Below is given the average 

 composition of anthracite from the Kohinoor Colliery, Shenan- 

 doah, Pennsylvania. 



Water 3.163% 



Volatile matter 3.717 



Eixed carbon 81.143 



Sulphur 0.899 



Ash 11.078 



100.000% 



The principal anthracite coal regions of the United States are 

 in eastern Pennsylvania. From here westward throughout the 

 interior states to the front range of the Rocky Mountains the 

 coals are all soft, or bituminous coals. Those of the Eocky 

 Mountain regions proper are largely lignitic, passing into the 

 bituminous yarieties. 



(4) Phosphatic Group: Phosphatic Sandstone; Bone Breccia; 

 Guano ; Coprolite Nodules. — This is a group of rocks limited in 

 extent, but nevertheless of considerable economic importance, 

 owing to the high values of certain varieties for fertilizing pur- 

 poses. Guano consists mainly of the excrement of sea fowls, and 

 is to be found in beds of any importance only in rainless regions 

 like those of the western coast of South America and southern 

 Africa. The most noted deposits are on small islands off the 

 coast of Peru. Immense flocks of sea fowls have, in the course 

 of centuries, covered the ground with an accumulation of their 

 droppings to a depth of sometimes 30 to 80 feet, or even more. 



An analysis of American guano gave: Combustible organic 



^ F. P. Dewey, Bull. 42, U. S. National Museum, 1891. 



