31 



TAB. CCCXX. 



S I L E X axinimorphum. 

 Violet Schorl, or Thumerstone. 



Class 2. Earths. Order I. Homogeneous. 



Gen. Silex. Spec. Thumerstone. 



Syn. Schorl violet. Joum. de Physique, 1785, Janv. 



p. 66. 

 Schorl transparent lenticulaire. De Lisle, 2. 353. 

 Yanolithe. Lamelherie, Sciagr. 1. 287. 

 La Pierre de Thum, ou Le Thumerstein* Broch. 



1. 236. 

 Thumerstone. Kinv. 1. 273. 

 Axinite. Haiiy, 3. 22. Karst. p. 22. 



I do not know of this substance being found in Great 

 Britain, excepting in the parish of St. Just in Cornwall. 

 It is found in many places abroad, as in Siberia, Norway, 

 Dauphiny, and at Thum in Saxony, whence its name 

 Thumerstein, it having been first discovered at that place. 



We find it crystallized in very oblique rhombs—see the 

 right hand lower figure. Its primitive is a rhomboidal prism, 

 similar to that of the Sulphate of Barytes- — see the left 

 hand figure. It is mostly of a dull purplish colour, whence 

 its name Violet Schorl ; though it is sometimes blueish, 

 brownish, or grayish. 



In all the British specimens the crystals are confusedly 

 grouped and small, the foreign ones being often as large as 



