JASPER. 545 



of great interest by mineralogists or lapidaries, 

 however unimportant they may be in a geological 

 view, renders it impossible to know all the sub- 

 stances which have been designated by this term, 

 but the following may be enumerated. 



An instance of the extreme laxity in the use 

 of this name, is found in the calcareous stalag- 

 mites, sometimes also called onyx-alabaster, which 

 have been thus denominated ; but these instances 

 are too striking to be the cause of error to geolo- 

 gists. The striped jasper, however, of many 

 writers, -which might be a source of confusion, 

 requires notice ; as it is, in all cases, a variety of 

 siliceous schist, or of some analogous substance. 



Some of the cherts that are coloured by chlo- 

 rite, and which are merely varieties of heliotrope, 

 have also been called jasper ; as have many other 

 cherty substances which are here treated of in 

 the following chapter; the name being given to 

 them, generally, where they have been remark- 

 able for their colours. 



Veinstones, consisting of various fragments 

 entangled in agate, have also acquired this name 

 among collectors ; and it has indeed frequently 



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