RE-EXAMINATION OF AMERICAN MINERALS. 147 



An interesting fact connected with this mineral, as shown by 

 this investigation, is, that although not crystalline, or at least 

 very obscurely so, yet coming as it does from three localities so 

 widely separated as Thuringia, the Potomac, and Arkansas, it 

 is nevertheless found quite unmixed with any other mineral, 

 as the analyses indicate. 



41. Xenotime of Georgia. 



In examining, a few years ago, some of the residue of gold 

 washings from Clarksville, G-eorgia, in the possession of Prof. 

 G-ibbes, of Charleston, I observed some small octahedral crystals 

 associated with zircon, titaniferous iron, and kyanite. Two or 

 three of the most perfect were selected ; and, having no goni- 

 ometer at hand, they were sent to Mr. Teschemacher, who 

 referred them, after a partial examination, to zircon. Prof. 

 Gibbes subsequently examined their form, and pronounced them 

 xenotime (Amer. Jour. Science and Arts, 2d series, xiii, 143). 

 Since then, from material that had been placed in my hands by 

 that gentleman, nearly a gramme of the substance has been pro- 

 cured, and upon that the following examination has been made. 



Some of the crystals are exceedingly short prisms, sur- 

 mounted by four-sided pyramids, but most of them are without 

 the prism, the summits coming together forming a flattened 

 octahedron. The measurements made were : over the pyra- 

 midal edge 123° 10'; over basal 81° 30'; face of pyramid on prism 

 131° 40'. The above measurements can be made with perfect 

 accuracy ; not so the faces of the prisms on each other ; and, as 

 far as I could make it out, I am inclined to think that they are 

 not square prisms, but rhombic prisms of 93°. Its hardness is 

 4.5, specific gravity 4.54, and the physical characters those 

 given for xenotime. 



It was decomposed by fusion with carbonate of soda and 



silica, and analyzed with the following results : 



Phosphoric acid 32.45 



Yttria 54.18 



Oxide of cerium (with a little La and £>) 11.03 



Oxide of iron 2.06 



Silica 89 



100.56 

 This analysis will be seen to differ from that of the xeno- 

 time of Hitteroe, Sweden, by Berzelius, in that a portion of the 



