38 
MINERALOGY. 
CHAPTER IIL 
MINERALOGICAL CONSTITUTION OF THE EARTH's SURFACE, 
Simple Minerals : Quartz, Feldspar, Mica, Talc, Chlorite, Horn- 
blende, Serpentine, Limestone, Slate and Clay, and Augite. 
—Minerals found in Veins or Beds : Iron, Lead, Gold, Silver, 
Tin, Copper, Zinc, Mercury, Manganese, Titonium, Bismuth, 
Antimony, Cobalt, 
We have now described, in a very brief manner, 
some of the elementary substances of which the sol- 
id as well as fluid matter of the earth is composed ; 
and we have found that the four earths, silex, alu- 
mine, Ume^ and magnesia, constitute at least nineteen 
parts out of twenty of the known solid matter of 
the globe, variously intermixed and aggregated to- 
gether. These materials form the chief proportion 
of all loose soils, and also of the softer species of 
stone, which are, in fact, the same substances in a 
more compact form. Thus most kinds of sand- 
stone are nothing more than loose sands or silex 
cemented together ; the softer kinds of slates, or 
those which readily soften and crumble away on 
exposure to air and moisture, are nothing more 
than indurated clays or alumine ; and those kinds 
of limestone which may be readily cut and worked 
are almost the same thing as chalk, but in a state 
of greater induration ; while marl, which is often 
very hard when first taken from the ground, is 
merely an indurated admixture of argillaceous and 
calcareous matter.* Although the varieties of 
stones and rocks appear to be so numerous, yet, on 
examination, we shall find that the simple minerals 
* Burr's Practical Geology. 
