154 



It is unnecessary to do more than name the 

 granular, fibrous, and scaly, fractures ; as they 

 must be already understood from the description 

 of the several textures to which they belong, and 

 with which they are almost synonymous. 



The remaining circumstances by which rocks 

 are characterized are of a miscellaneous nature, 

 and do not contain any material subordinate 

 varieties. 



HARDNESS. 



The range of hardness in rocks extends from 

 that of quartz to that of chalk. To describe the 

 various intermediate degrees accurately, is im- 

 possible, nor is it necessary. A sufficient notion 

 of most of them may be conveyed, partly by com* 

 parison with those two extremes, which must be 

 well known to every one, and, partly, by stating 

 the comparative facility with which such rocks 

 yield to the point of a knife, or of other familiar 

 objects. To give fire with steel, is an inaccurate 



