278 «=D. W. Barton on the Virgima Fluor Spar. 
white, red, violet and dark blue, approaching, when in larger 
masses, near to black. ave obtained many well defined 
erystals, and I have little doubt that more diligent research 
would discover specimens which would grace even your 
splendid collection. 
A few miles east of the fluat of Lime is an extensive 
stratum of crystallized carbonate of lime, much of which is 
remarkably transparent, equalling in beauty the Iceland spar. 
It possesses the property of double refraction in a very per- 
ceptible degree. I found many detached masses of the 
same substance, which by the attrition of water had been 
worn intoa spherical form. These frem their translucence 
exhibit externally the appearance of the Scotch pebble. 
The outer coating is beautifully tinged by the oxide of iron, 
and a fracture presents an elegant succession of fine col- 
ours 
source of rational amusemen 
Yours with respect, 
D. W. BARTON. 
November, 1821. 
ca 
