202 DESCRIPTIONS OF MINERALS. 



purple fluor- spar ; sometimes reddish-brown. Opaque. 

 Lustre glistening. II. = 4-5. G.=3*4-3'5. 



Composition. Fluorine 25*1, lime 47*6, cerium protox- 

 ide 18*2, and yttria 9*1. Infusible alone before the blow- 

 pipe. 



Obs. From Finbo and Broddbo, near Fahlun, in Sweden, 

 with albite and topaz in quartz. Also from Mt. Mica, 

 Maine ; Massachusetts, probably in Worcester County; and 

 from Amity, Orange County, X.Y. 



Fluocerite and Fluoeerine are other fluorides containing cerium, from 

 Sweden. 



Samarskite. 



Trimetric. I A 1=122° 46'. Usually massive, without 

 cleavage, with a velvet-black color and shining submetallic 

 lustre. Streak dark-reddish brown. Opaque. H.= 5*5-6. 

 G.=5-6-5-S. 



Composition. Analyses of the American afford columbic 

 and tantalic pentoxide, with sesquioxides of yttrium (12-15 

 per cent.), cerium, iron, and oxide of uranium. In the 

 closed tube decrepitates and glows. B.B. fuses on the 

 edges to a black glass. With salt of phosphorus in both 

 flames, an emerald-green bead. 



Obs. Occurs at Miask, in the Ural ; also in masses, 

 sometimes weighing many pounds, at the Mica mines of 

 Western North Carolina, along with columbite. 



Kolilite is near samarskite, but contains 4"G2 of water. 



Fergusonite. A hydrous columbate of yttrium, erbium, cerium. 

 Color brownish black ; lustre dull, but brilliantly vitreous on a sur- 

 face of fracture. B.B. infusible, but loses its color. From Sweden, 

 Cape Farewell, Greenland, and Rockport, Mass. 



Kochelite is near fergusonite. 



Yttro-tantalite. A tantalate and columbate of yttrium, erbium, and 

 iron. The different varieties are the black, the yellow, and brown or 

 dark- colored. They are infusible. From Ttterby, Sweden, and at 

 Broddbo and Finbo, near Fahlun. 



Euxenite. A columbate and tantalate of yttrium, uranium, erbium, 

 and cerium. Massive. Color brownish black. Streak reddish brown, 

 B.B. infusible. From Norway ; also from X. Carolina. 

 . Sipylite. A columbate and tantalate of erbium and yttrium, re^ 

 sembling fergusonite in aspect. From Amherst County, Va. 



PyrocMore, Microlite, Disanalyte, under Calcium, p* 214. 



JEscTiynite. In crystals, black to brownish yellow ; lustre resinous 

 to submetallic ; streak gray to yellowish brown or black. H.=5-6. 

 G". =4"9-51. A columbate* and'titanate of cerium, thorium, and lan- 

 thanum. From Miask, in the Urals, in feldspar with mica and zircon. 



Polymignite and Polycrase. Related to seschynite. 



