45 



TAB. CXXIV. 



SILEX magnesiatus : var, amianthiformis. 



o 



Wood-like Amianthus, or Asbestus. 



Div. 2. Imitative. 



This is formed in upright and often curved filaments, some- 

 times in masses or plates. It is often indurated in a high 

 degree, and resembles wood petrified — see the lower figure. 

 The present kind is found at Portsoy in Scotland in great 

 abundance and variety, crossing in many directions through 

 the Serpentine rocks. The upper specimen was given me by 

 Lord Seaforth. It is somewhat undulated, and varies in 

 colour; is harder in some parts, and softer in others. In 

 some it may be separated into flocculi with the finger nail, 

 and in others it is so hard as to bear a good polish ; when 

 it is more brittle, and approaches to Actinolite. The lower 

 piece was lent me by my friend G. Laing, Esq.; it comes 

 also from Portsoy, and is remarkable for filling a narrow 

 flaw in the Serpentine in a very thin plate, and showing 

 fractures transverse to the striae at nearly right angles. It 

 is also very regular in hardness, so as to take a good polish 

 all over the face ; being about the hardness of common 

 marble. This, and many earthy substances, resemble wood, 

 especially the undulating slaty or irregularly schistiform 

 locks. 



