220 Discovery of Columbite in Chesterfield, Mass. 
CoLuMBITE. 
In May, 1828, while on a visit to the remarkable deposit of 
tourmalines in Chesterfield, Mass., my attention was calle 
to a loose rock in the foundation of a stone fence, by the large 
and delicate folia of yellow mica it contained. 
bore signs of having had fragments detached from it before; 
but the wall being now displaced for the purpose of affording 
a passage to cattle, | was enabled with the aid of a hammer, 
to reduce it completely to fragments. ‘Towards its centre, I 
found imbedded, a number of black metallic crystals, whose 
form and weight led me at once to think of Columbite. They 
were situated within a few inches of each other; sometimes 
engaged in feldspar, at others in beryl, and occasionally, 
between the folia of the mica. They presented much di- 
versity in their dimensions; the smallest of them not weigh- 
ing above 15.grs., and the largest a little above 400 grs. 
he weight of all the crystals and fragments obtained, as 
near as I can estimate them at present, did not exceed 12 
or 1400 grs. Not having unti] very lately, been able com- 
pletely to verify my conjecture, concerning their nature, I 
have withheld until the present moment all notice of the lo- 
eality; which I now take much pleasure in making public, 
together with a minute account of the steps followed in ar- 
riving at the conclusions here announced, 
Mmeralogical Description. 
quent modification observed among these crystals. Their 
angles are determined, by the common goniometer, 
ad. ; . . 90 ,00 
2 2 gee rs 133 ,00 
Mona . - 116 00 
Tono. . 156 ,00 
