1824.] 



Dr. Tovry on Columbite. 



361 



slightly rounded on the edges. Borax dissolves it very slowly, 

 forming a pale yellowish glass. The crystals are very minute 

 being- seldom greater in diameter than a common pin, and often 

 much less ; yet many are extremely perfect. The greater num- 

 ber of these crystals is imbedded in the singular friable garnet, 

 which Mr. Seybert has ascertained to contain 30 per cent, of 

 manganese. In one instance, I found them iong, very slender, 

 and disposed in a radiating manner. They are often grouped, 

 or intersecting, and are very brittle. The form of the crystal is 

 that of a compressed rectangular prism, usually truncated on the 

 lateral edges, or a four-sided pyramid, two sides of which are, in 

 most instances, unduly extended. According to Phillips, the 

 primary form of the columbite is a right rectangular prism. The 

 annexed figures represent two of the crystals with the measure- 

 ment of the angles taken with the reflecting goniometer. No. 1 

 is the most common. This, it will be seen, much resembles a 

 figure of columbite in the third edition of Phillips's Mineralogy, 

 except in some minor truncations. 



Fig. I. 



Fig. 2. 



P on M, or T 90 00 



M on T 90 00 



T on d\ orM on ds.. 157 00 



T on d<z or M on dz. .129 50 



Tonrfs 102 50 



A small quantity of the powdered mineral was fused with six 

 parts of potash and one cf borax. A mass of a deep green 

 colour was obtained. Muriatic acid poured on this left a white 

 powder, which, from the small quantity of the ore operated upon, 

 could not be particularly examined, but it appeared to be oxide 

 of columbium. The muriatic solution was found to contain 

 iron and manganese. I regret exceedingly not having a suffi- 

 cient quantity of the mineral to make a complete analysis, but 

 its external characters, crystalline form, and the few chemical 

 experiments I have made, together with the great probability of 

 the substance I examined being the same alluded to by Berze- 

 lius, leave little doubt that it is columbite. Still, I hope, by 

 examining a considerable number of specimens, to find a suffi- 

 cient quantity of the ore to undertake a detailed analysis. 



If I am correct in my determination of the Haddam mineral, 

 we have a clue, perhaps, to the discovery of the long-lost colum- 



