224 Discovery of Columbite in Chesterfield, Mass. 



It was not my object to determine the proportions among 

 the constituents of the present mineral, and I am therefore 

 unable to make any precise statement upon the subject : but 

 having paid some attention to the relative bulks of the pre- 

 cipitates in one or two instances, I was led to conjecture, that 

 the columbic acid does not form less than two thirds of 

 the mineral, and that the tin is present in a proportion, but 

 little inferior, either to the iron or the manganese ; while the 

 Hme exists only as a trace. 



Before concluding this account, T would remark, that I am 

 not without hope, that a further supply of this desirable min- 

 eral, may be found in Chesterfield ; although all search which 

 has been made, since the discovery of my specimens, has 

 proved ineffectual. The fact, that the loose mass which af- 

 forded them, was situated, at a little distance from the 

 south end of the tourmaline ledge,* and that it corres- 

 ponded so very remarkably in its general structure with that 

 part of the rock, seems to indicate that this was its original 

 deposit ; and holds out, I think, sufficient inducement to the 

 collector to search for it, in this direction. 



It may also appear worthy of notice, as it seems to indi- 

 cate that columbite is probably a more widely diffiised sub- 

 stance, than has been supposed, that, I possess minute masses 

 of it from two places in Goshen : one^ from the farm of Mr. 

 Weeks ; and the other, four miles distant, from the first discov- 

 ered locality of spodumene. In both of these instances, they 

 are engaged in the spodumene, in the form of imperfectly 

 tabular crystals. I have also noticed the same substance, in 

 very distinct, though minute crystals in Middletown; (Conn.) 

 upon one of the high granite hills, about half a mile north 

 east of the tourmaline deposit. It occurred in a loose frag- 

 ment of granite, consisting chiefly of beryl.t 



* Now famous throughout the mineralogical world, for its beautiful parti- 

 colored tourmalines. 



t When at Haddam, about a year since, one of the quarry men, showed me 

 a black crystal, nearly an inch in diameter ; which he informed me, had been 

 considered columbite. It was black spinelle ; but the summits of two of its 

 opposite pyramids being wanting, its form was not at fij'st distinguishable. I 

 mention this fact, not as doubting at all the existence of columbite at Haddam, 

 for this is established upon the best authority ; but to put the collector, who vis- 

 its that spot, on his guard, lest he should be deceived in the specimens offered 

 him, since both these substances occur together in the chrysoberyl rock and 

 often in masses so minute, that their crystalline form cannot well be distinguish- 

 ed. The spinelle, is more abundant than the columbite ; an opinion of tlie 

 scarceness of which, may be formed from the fact, that I never have met with 

 a single specimen of it, among the products afforded by three blasts of this rock, 

 which I have had, at different times. 



