ANALYSES OF ALLANITE 473 



recently donated the writer by Mr. George L. English, are entirely cov- 

 ered by a crust of the altered mineral derived from weathering. The 

 allanite is intergrown with quartz and is altered to the usual reddish 

 brown crust with, in places, an outer thin layer of yellow brown to buff 

 in color. The powder is soluble in hot dilute HCl, yielding some gelati- 

 nous silica ; is infusible before the blow-pipe, becoming magnetic ; yields 

 water in closed tube when heated, which reacts neutral; and does not 

 react for carbonates. The weathered product was studied microscopically 

 and found to be heterogeneous, in common with that from other localities, 

 composed of both crystalline and isotropic grains each having variable 

 properties. 



ANALYSES OF ALLANITE FROM THE NEW ENGLAND AND MIDDLE ATLANTIC 



STATES 



While the nine analyses of allanite tabulated below from the New Eng- 

 land and Middle Atlantic States are lacking in some cases in complete- 

 ness and otherwise are unsatisfactory, they will illustrate in a general 

 way the wide variation in the composition of the mineral — an important 

 feature discussed elsewhere in this paper. A second noteworthy fea- 

 ture is the absence of the yttria earths from seven of the nine analyses, 

 amounting to less than 2 per cent in each of the two in which they are 

 reported. These analyses should be compared with those from Virginia 

 and North Carolina on page 479. 



