82 Chemical Examination of American Minerals. 



Thus the existence of soda in the Kilpatrick variety was 

 confirmed. It is obvious, however, that the Lochwinnoch 

 specimens are purer than those of Kilpatrick, and that soda 

 does not exist in them. Of course, the true type of this mine- 

 ral must be, 3 AZS + CS -\-.2hAq. 



30. NUTTALLITE. 



I got a specimen of this mineral (constituted into a new 

 species by Mr. Brooke) about two years ago from Mr. Nut- 

 tall. But it was so small, and apparently so impure, that I 

 did not think it worth while to examine it. Since that time, 

 I have got specimens of it both from Mr. Nuttall and Dr. 

 Torrey, some of which being much purer, I took the oppor- 

 tunity of analyzing it, as hitherto nobody has made us ac- 

 quainted with its chemical constitution. The locality is Bol- 

 ton, Massachusetts. Dr. Torrey informs me that he has seen 

 perfect crystals of it. 



It occurs in crystals, in a rock consisting partly of calca- 

 reous spar, and partly of a green colored mineral in grains, 

 having the aspect of amphibole. Small brown-colored specks 

 were interspersed, which might be sphene. 



The crystals were eight-sided prisms, without any terminal 

 planes. These crystals (as Mr. Brooke first observed) cleave 

 in the direction of a right square prism, which seems to be its 

 primary form. 



Color white, in some parts of the crystal yellowish, in 

 others bluish or greenish. The yellowish-white portions are 

 translucent, or almost transparent ; the bluish nearly opaque. 

 Is not this owing to the presence of a foreign substance ^ 



Lustre glassy, or very slightly inclining to resinous. 



Easily scratched by the knife. 



Specific gravity varied in different trials, from 2*748 to 

 2-758. 



