256 Dr T. THOMSON'S Account of the 



or it is a compound of 



3 atoms bisilicate of magnesia. 

 1 atom tersilicate of lime. 



Now, this is the variety of amphibole to which the amianthus 

 approaches nearest. 



8. Nutallite. 



This mineral was brought into this country some years ago by 

 Mr NUTALL. Its locality is Bolton, Massachusets. It was 

 considered in America as elaeolite. Mr BROOKE examined it in 

 1824, found the crystals much softer, and obtained by cleavage 

 a right square prism, which he considered as the primary form. 

 He named the mineral after Mr NUTALL, who first brought it 

 to this country. For the specimens in my possession, I am in- 

 debted to Mr NUTALL, who was so obliging as to send me two or 

 three pretty pure pieces of it, one of which was submitted to 

 analysis. The crystals are imbedded in a rock composed of cal- 

 careous spar, and a green coloured mineral, in grains having the 

 aspect of amphibole. 



The crystals of Nutallite in my possession, are eight-sided 

 prisms, which cleave in the direction of the faces of a right square 

 prism. 



The colour is white ; in some parts of the crystal yellowish, in 

 others bluish or greenish. The yellowish-white parts of the 

 crystal are transparent ; the bluish nearly opaque ; showing evi- 

 dently the presence of some foreign matter. Streak white. 

 Lustre vitreous. 

 Easily scratches by the knife. 



Specific gravity in different specimens was found to vary from 

 2.748 to 2.758. 



