19 
TAG COX, 
Tue present specimen is part of a large aggregated * mass 
sent me by the Rev. Mr. Gregor from’ Cornwall, and is 
composed of numerous crystals forming several distinct 
varieties, where they are ‘not confusedly intermixed with 
each other. It seems to have been found in the vicinity of 
a red Oxide of Iron, as the colour about it indicates. In 
Mr. Gregor’s account of the analysis (Nicholson’s Journal, 
vol. 4. 312), it appears that it contains Oxide of Titanium. 
It is somewhat remarkable that the red Schorl of Siberia, and » 
the large specimen of Rubellite or Titanitet (as it has been 
called) in the possession of the Right Hon. Charles Gre- 
ville, are by some considered as varieties of Tourmaline. 
The crystals in this specimen show many of the faces 
which are generally found on Tourmaline ; viz. the three- 
sided prism, truncated at the edges, and formed into a six- 
sided prism; the same with two or more bevillings on the 
edges, &c.—The fracture is somewhat conchoidal, and the 
- primitive form is a rhomboidal parallelopiped. 
Tourmaline is harder than Quartz. ~ With moderate heat 
it becomes electric, attracting and repelling ashes, &c.t, a 
__ * Schorl is said to be mostly aggregated, and Tourmaline to be chiefly 
imbedded in single crystals. 
+ This was presented to Colonel Symes by the king of Ava, and is said to 
be worth a thousand pounds. 
_ ¢ Foreign specimens, sometimes cut and polished, are known by this 
property. 
Cc 2 
