On Columbile and other North American Minerals. 91 



The crystals are very minute, being seldom greater in dia- 

 meter than a common pin, and often much less ; yet many are 

 extremely perfect. The greater number 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 long, 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 late- 

 ral 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 mea- 

 surement of the angles taken with the reflecting goniometer. 

 No. 1 is the most common. This, it will be seen, much re- 

 sembles a figure of Columbite in the 3d edition of Phillips's 

 Mineralogy, except in some of the minor truncations. 





M 



Mc,.l. 



M 



P on M or T 90.00 



MouT 90.00 



T on d 1 or M on 'd 3 - - 157.00 



2 or 2 - - 129.50 



3 102.50 



A small quantity of the powdered mineral was fused with 

 six parts of potash and one of 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 ope- 

 rated upon, could not be particularly examined, but it appear- 

 ed to be oxyd of Columbium. The muriatic solution was 

 found to contain iron and manganese. I regret exceedingly 



