J. L. Smith — Examination of American Minerals. 367 



It will be seen that the special difference between tin's min- 

 eral and pyrochlore is that its predominating ba.-e is uranium 

 oxide, which last mineral, according to Wohler's analysis of 

 that from Miask, does not contain any of this oxide, though 

 the analyses of others give a small quantity of it It is to be 

 supposed that Wohler examined the best and purest type of 

 the mineral in that from Miask. 



Hogersite, a 



On some of the samarskite, but more especially on the euxe- 

 nite, a white crust was found adhering with some degree of 

 firmness, and on examining it under the glass, it presented a 

 mammillary structure, sometimes like little pearly beads. When 

 on the euxenite it is more readily separated than when on 

 Bamarskite. By pressing on it with a sharp point, it becomes 

 detached in small fragments. 



I have called this mineral Eogersite, in honor of the Ameri- 

 can geological Nestor, Wm. B. Kogers, whom we all delight to 

 honor for his important labors in scientific and economic geol- 

 ogy, from an early date up to the present day. 



The quantity that has as yet been discovered is vei 

 Mr. Ralston possesses the finest specimen, which is about the 

 size of the hand, with four or five grams of this mineral on the 

 surface, quite pure and very characteristic. I had to operate 

 on a great number of small pieces carefully detached, winch 

 have enabled me to est;. :or - 



It is readily recognized by its well marked mammillary struc- 

 ture even when the fragment is quite small. Its hardness is 

 about 3-5; specific gravity 3-313. 



I made two analyses, each time on small portions. The 

 results furnished were : 



Water - —.17*41 16-14 



Columbic acid 18 * 10 20 ' 21 



Yttria, etc. . _ 60 ' 12 



In the second analysis, owing to an accident, the yttria was 

 lost; the first also shows about 4 per cent not accountea ror 



These analyses are to be taken only as approximative, for 

 before complete and roliahh- anJ.v^ -' M; "..iieral can be 

 made, a larger quantity will be required The mineral is an 

 interesting one as being the first columbate discovered so 

 largely hydrated. It VT the deCOm " 



Position of either samarskite, or euxenite, or both. 

 Ferguson ite. 



Two years ago a dark brown mineral, with a remarkably 

 " - - . .- --■■--.- -■'■'--■''-■■-- ;-;■ 



W. E. Knowlton of Boston, who obtained it from the granite 



