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American Geological Society. 143 
Mr. T. D. Porter presented some of the finest crystals of 
sed oxid of titanium that have been any where found; the 
following memorandum accompanied them. 
This titanium which I discovered in 1818, exists very 
well crystalized, and in comparative abundance, in masses 
quartz which are scattered over the surface throughout 
the counties of Amherst, Campbell and Bedford, about twenty 
miles above Richmond in-Virginia. Probably also it may 
be found in other counties contiguous to these, as the same 
rocks occur very extensively in all that quarter of the state ; 
but I never had an opportunity to make any examination 
except in those I have mentioned. 
Many of the specimens which I procured are superior 
both in size and in beauty, to any of the same species in the 
Cabinets which I have seen. A fragment of one crystal which 
Lobtained, measures 1,); in chesin diameter, and others are 
nearly as large. I have one specimen 3,% inches in length, 
and another more than 3}: both these are mutilated—the - 
latter is broken off at each end, and was probably much 
larger ; it is of the size of one’s finger. The larger speci- 
mens are very liable to be thus injured, being exceedingly 
brittle. Their fracture is commonly foliated longitudinally 
and vitreous in the other direction. Frequently they are 
completely penetrated by quartz in the same manner as 
he green tourmaline of Massachusetts is by the Rubellite. _ 
ike the different varieties of schorl, the greater part o! 
the crystals were so compressed and striated, that their 
figure was very variable, oftener nearly cylindrical than of 
any regular prismatic form. I met with two or three spe- 
cimens which were four sided prisms, truncated on each of 
the angles, having their terminations broken off and with a 
single crystal of four sides, which like those of the specimens 
Just mentioned, seemed to meet at right angles and termi- 
nated very handsomely by a pyramid, whose sides corres- 
ponded with those of the prism. Many examples of crys- 
talline termination were observed, but generally they were 
exceedingly irregular ; sometimes one of the terminal planes 
was so large as almost entirely to obliterate the remainder. 
I believe I saw but two crystals with both ends perfect, 
among more than a hundred specimens which I collected. | 
e proportion of the titanium found here, exhibited 
that peculiarity of configuration which is so characteristic of 
