CHARACTER OF WEATHERED PRODUCTS 



487 



powder blackens and becomes magnetic; with borax bead reacts for iron; 

 heated in closed tube, yields water having neutral reaction. Specific 

 gravity in powder, 2.606. 





Roanoke Co., 

 Virgfinia 



Amherst Co., 

 Virginia 



Anderson Co , 

 South Carolina 



Chester Co., 

 Pennsylvania 



Yields water in closed 

 tube. 



Faintly 

 alkaline 



Faintly 

 alkaline 



Neutral 



Neutral 



Soluble in hotdil. HCl. 



Gelatinizes 



Gelatinizes 



Gelatinizes 



Gelatinizes 



Infusible BB. Residue 

 insoluble or only 

 sligfhtly soluble. 



Nonmagnetic 



Nonmagnetic 



Nonmagnetic 



Magnetic 



Presence of CO2 



Slight 



Faint 



None 



None 



Weathering op Allanite in Virginia Localities 



introductory statement 



Fresh and weathered masses of allanite, weighing up to several pounds, 

 from Amherst, Nelson, and Koanoke counties, Virginia, have afforded 

 excellent material for a study of the weathering of the mineral and are 

 regarded as typical for allanite alteration in general. Chemical analyses 

 of both the fresh and the decomposed allanite from each locality have 

 been made, which will serve to emphasize the difference in composition 

 between the fresh and the weathered mineral. These are compared and 

 the changes incident to weathering of the allanite are discussed below. 

 Careful investigation of the mineral from the several localities, both in 

 the field and in the laboratory, clearly shows the form of weathering to 

 be chemical and not physical in nature. 



PREVIOUS WORK 



After a careful search of the literature, the writer has found records of 

 only three analyses of the weathered product of allanite. These were 

 made by Santos^*^ and Valentine^^ on material collected from Amherst 

 and Nelson counties, A'irginia, and are quoted by both Dana^^ and 

 Hintze.^- 



89 J. R. Santos : Chem. News, vol, .38, 1878, p. 95. 

 '•> E. P. Valentine : Am. Chem. .Tour., vol. 7, 1885-1886, p. 178. 

 ■^1 E. S. Dana : A System of Mineralogy, 1900, 6th edition, p. 526. 

 " C. Hintze : Handbuch der Mineralogie, 1887, p. 276. 



