552 JASPER. 



sumed that the student will rarely be at a loss to 

 recognize this rock, wherever, at least, its cha- 

 racters are perfect: cases of transition must be 

 studied in their geological positions. 



The colours of jasper are infinitely various, 

 and are the principal cause of its estimation among 

 mineralogists and lapidaries. They are also, in 

 general, much more brilliant and decided than 

 those of any other rock except limestone ; yet the 

 student will, from the preceding description, 

 beware of using them as an empirical character 

 to the neglect of others. Red of various hues, 

 ochre yellow, greens, browns, greys of all tones, 

 and black, are the prevailing tints; and they 

 occur in every mode of intermixture, so as to 

 present almost infinite varieties. From a wish to 

 conform to the popular practice respecting this 

 rock, of which the mere mineral characters are 

 not much varied, these distinctions have therefore 

 been introduced into the Synopsis in a more con- 

 spicuous manner than has been adopted with 

 regard to any other substance. 



