278 =D. W. Barton on the Virgima Fluor Spar. 
white, red, violet and dark blue, approaching, when in larger 
masses, near to black. I have obtained many well defined 
crystals, and [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 into a 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. 
There is another mineral which exists abundantly i in es 
neighbourhood of Winchester. It is a species of iron ore 
very distinctly crystallized. ‘These crystals are probably 
octahedral, as the projecting half (the only visible part) is a 
four sided ‘pyramid ; ; the angles of whose base are very une- 
qual. ‘The value of this mineral may make it worthy of a 
more minute investigation, and on some future occasion I may 
communicate a more particular account of it. As soon as a 
convenient opportunity occurs, I will forward to you speci- 
mens of the two Jast minerals with some others, which are 
not worthy of earlier notice. I will only mention that I find 
the Cornu Ammonis abundant in this valley. 
Permit me, Sir, on this occasion to express my gratitude 
to you for inspiring a fondness for those sciences, which 
however imperfectly cultivated, already constitute a 2 Seite 
source of rational amusement. 
Yours with respect, 
D. W. BARTON. 
November, 1821. 
