464 JOURNAL OF the; WASHINGTON ACADEMY OF SCIENCES VOL. 11, NO. 19 



100.15 100.68 99.60 100.32 100.74 100.73 99.96 100.11 99.90 99.06 



(1) Biotite granite, Tilden Street quarry. Washington analyst. 



(2) Biotite granite, Newark Street quarry. Washington analyst. 



(3) Biotite granite. Broad Branch Road quarry. Packard analyst. G. P. Merrill. 

 Bull. Geol. Soc. Amer. 6: 321. 1895. 



(4) Biotite granite, Rowlandsville, Maryland. HillEbrand analyst. G. H. Williams, 

 U. S. Geol. Survey Ann. Rep. 15: 672. 1895. 



(5) Muscovite-biotite granite, River Road quarry. Washington analyst. 



(6) Muscovite-biotite granite (foliated). Rodman Street opening, Washington analyst. 



(7) Mu.scovite-biotite granite. Guilford, Maryland. HillEbrand analyst. C. R. 

 Keyes. U. S. Geol. Survey Ann. Rep. IS: 716. 1895. 



(8) Quartz vein in granite, River Road quarry. Washington analyst. 



(9) Northfieldite, Pelham, Massachusetts. E. T. Allen analyst. B. K. Emerson, 

 Amer. Journ. Sci. 40: 215. 1915. 



(10) Quartzose border of granite. A. R. DwerryhousE analyst. DwERRYHOUSE, 

 Quart. Journ. Geol. Soc. 65: 64. 1909. 



TABLE 3. Norms of Biotite Granite 



(2) 

 27.06 

 17.79 

 27.77 

 15.85 



0.41 



8.63 

 1.86 

 0.76 

 0.34 



(4) 



28.26 



12.23 



22.53 



22.52 



none 



1.19 



8.90 



2.32 



0.91 



0.34 



(1) Tilden vStreet. Symbol (1)11.4. "3.3(4). 



(2) Newark Street. Symbol I(II).4.(2)3.3(4). 

 (4) Rowlandsville. Symbol (I)II."4.3."4. 



