516 



Hidden and Warren — Yttrocrasite. 



Before the blowpipe the mineral is infusible, assumes a 

 dark grayish color and cracks open to a slight extent. In the 

 closed tube it decrepitates slightly, gives off water and car- 

 bon dioxide at a temperature slightly below redness. The 

 reactions with fluxes on platinum wire are not decisive. It is 

 easily decomposed by hydrofluoric acid, leaving a light green- 

 ish residue of earth fluorides. If finely powdered it is soluble 

 with slight effervescence when boiled in strong sulphuric 

 acid, and yields a somewhat opalescent, pale yellowish green 

 solution. If hydrochoric acid and zinc are added to this, 

 a violet color is at first obtained, and this gradually changes to 

 a blue-gray, and finally to a deep blue. (In this connection we 

 would state that the South Carolina polycrase, when finally 

 pulverized, makes a perfectly clear green solution when boiled 

 with strong sulphuric acid, and leaves no residue.) 



The material analyzed was that portion of the crystal which 

 showed under the microscope practically none of the black 

 specks above referred to. 



The specific gravity was found to be 4*8043 at 17° Cent., the 

 mean of two careful determinations on the chemical balance. 



The results of the chemical analysis (Warren) were as fol- 

 lows : 



Oxides. 



Per cent. 



Mol. wt. 



Eatio. 









TiO, 



49-72 



-r- 80-15 



= -620 " 









Nb.0. 



present 













Ta 2 6 



trace 













WO, 



1-87 



-4-332'8 



= -008 



>■ -645 



16-12 



16 



uo 3 



0-64 



-4-288'0 



= -002 









Si0 2 



trace 













co 2 



0*68 



-4- 44-0 



= -015 ■ 









(YtEr) 2 O s 



25-67 



-4-268'4 



= -096 



> -113 







Ce 2 3 , etc. 



2-92 



-4-331'0 



= -008 



2*82 



3 



Fe 2 3 



1-44 



-4-160-0 



= '009 j 



• 







Th0 2 



8-75 



-4-268-6 



= -033 ; 



- -040 



1-00 



1 



uo 2 



1-98 



-4-27T6 



= •007 \ 



PbO 



0-48 



-4-222-9 



= -oo2 : 









MnO 



0-13 



-4- 71*0 



= -001 



■ -036 



0*90 



1 



CaO 



1-83 



-4- 56-0 



= -033 ] 









M^O 



trace 













H 2 



4-36 



-4- 18-0 



= •242 



•242 



6-00 



6 



" hydrosc. 



o-io 













Total 



100-57 



The following points may be noted regarding the method of 

 analysis : Water and carbon dioxide were determined directly 

 by igniting the mineral in a platinum boat in a hard-glass com- 



