163 



TAB. CCCLXXXIX. 



S I L E X electricus. 

 Pointed Schorle, 



Among the many forms that this substance assumes, and 

 not rarely, is the present ; but it has not yet been described, 

 to my knowledge. It is composed of elongated prisms, a 

 smaller or greater number of which commencing at a point, 

 often diverge to great lengths, thickening more or less regu- 

 larly, as figured. I have them mostly six-sided, with some 

 of the angles here and there truncated longitudinally, so that 

 some have as many as twelve sides, giving the appearance of 

 a peg cut in angles and left without being rounded. I ex- 

 pect they are often of great length : what I have are only 

 about three inches long (sent me by the Rev. Patrick Forbes 

 lately mentioned), but these have no terminations. They 

 sometimes, however; end abruptly, as thehollowimpressions 

 show: they sometimes also have a transverse crack, which 

 is filled up with Quartz. Indeed it does not appear to me 

 that any one has yet made a research for the purpose of in- 

 vestigating to what length Schorle may shoot or lengthen : 

 perhaps this may be a hint towards some attempt of the 

 kind; which,however, is themoredifficult as it is so frequent- 

 ly among Quartz in the hard Granite Rocks : when, however, 

 it is found among the more micaceous parts of it in veins, 

 it may be better traced, as in such situations it is often very 

 long, but perhaps seldom so perfect. 



I was favoured with the upper specimen by the Earl of 

 Seaforth, from the neighbourhood of Portsoy in Banffshire. 

 In it the Schorle is passing through or among Felspar or 

 Kaolin and Quartz, leaving its impression where it has be- 

 come detached, which is often the case, as in some parts it 



