J. L. Smith — Examination of American Minerals. 363 



granular, but exist in large masses, so that in extracting the 

 fine blocks of mica, these are readily detached from the other 

 constituents of the granite. The samarskite is generally in 

 close relation to the feldspar, which last, in all the specimens I 

 have seen, was more or less disintegrated ; this arises no doubt 

 from the proximity of the samarskite to the surface, it not 

 having been found as yet in the unaltered granite. 



For some time after the discovery of this mineral, mineralo- 

 gists were not agreed as to its being samarskite. no crystals 

 having been found by which to establish its identity, mid the 

 partial analyses made not giving concordant results.' This dis- 

 v t. from the intermixture of other min- 

 erals, three of which I have detected, two of fhem being new. 



On one occasion 1 took a specimen of very compact mineral, 

 perfectly clean, and to casual observation perfectly uniform in 

 color and texture: on breaking off a portion from one end of 

 it and taking the specific gravity, 1 found it to be 5'221, which 

 was so much lower than that of samarskite that I passed it over 

 to my assistant for reexamination. His results corresponded 

 exactly with mine. 



I then broke off a piece immediately contiguous to the one 

 already examined and gravity o-682, being 



that of samarskite. On examining the first piece by breaking 

 off thin scales, I could detect that a portion of them had a very 

 dark brown luster, produced by the mixture of some euxenite, 

 a mineral that I bave discovered pure and in all stages of mix- 

 ture with the samarskite There is no difficulty, with some 

 httle experience, in obtaining any quantity of this mineral with 

 its usual characters. 



Aspect of the finest specimens.— -Intense jet black, and when 

 broken having a large brilliant conchoidal fracture, perfect, 

 even, and smooth, with the luster vitreous. 



It is exceedingly brittle, breaking like black obsidian, with 

 very sharp edges;' any one seeing it broken for the first time 

 would take it for black its weight 



would indicate that it was another mineral. All the pieces of 

 Pure samarskite are not equally brilliant iu fracture as above 

 described, but approach to it more or less. 



Hardness.— I should sav that it was -V5 to 6, nearer b, but 

 owing to the brittleness of the mineral it is not easy to fix its 

 exact hardness. 



Specific gravity. — 5 72. , , 



Crystalline form. — I am indebted to Mr. Ralston for^ the 



of the only specimens from wh 



f orm could be made out, and these bave been thoroughly 



described and studied by Mr. Edward S. Dana ; the examination 



made by th grapher is to be found in this 



