554 JASPER. 



c. Spotted, or variously mottled, in conse- 

 quence of a concretionary spheroidal 

 structure. 



The Siberian spotted jasper ranks under this 

 variety. The most common colours are, reddish 

 and pale ochre, obscure red and white, and brown 

 and ochre. 



C. Highly indurated, with an aspect approaching 

 to that of chert, or even to agate ; into which it passes, 

 as it does into chert and quartz. 



a. With a somewhat granular fracture. 



b. With a granular splintery fracture. 



c. With a splintery fracture passing to the 



conchoidal. 



d. With a flat fracture passing to the 



large conchoidal. 



The two latter varieties are among the most 

 esteemed, as assuming the best polish. The 

 colours most prevalent are reds and yellows, 

 single or intermixed in various ways. The va- 

 rieties under this head occur chiefly among the 

 primary rocks. 



D. Intermixed in various ways with chalcedony 

 either white or coloured, and, apparently, at times 

 passing into that substance: jasper-agate of lapidaries. 



The ornamental appearance is often produced 



