JOURNAL 



OF THE 



WASHINGTON ACADEMY OF SCIENCES 



Vol. VI MARCH 4, 1916 No. 5 



MINERALOGY.— A peculiar intergrowth of phosphate and sili- 

 cate minerals. Edgar T. Wherry, National Museum. 1 



A green and white substance occurring associated with varis- 

 cite in fissure veins in metamorphosed slate near Manhattan, 

 Nevada, was recently submitted to the U. S. National Museum 

 for identification by Mr. Percy Train of that place. 2 It appears 

 to be of sufficient interest to justify this preliminary announce- 

 ment of its character. 



The material presents the form of a "sulphate" green, glassy 

 mass, traversed by numerous sub-parallel wavy white lamellae, 

 varying from 1 mm. down to 0.05 mm. in thickness, but at the 

 latter size becoming too translucent to be distinguished, so that 

 the variation may well continue to still thinner dimensions. 

 Both minerals are practically amorphous, showing between 

 crossed nicols only traces of weakly doubly refracting material. 



A small sample of the purest green material which could be 

 separated by hand picking was submitted to J. E. Whitfield for 

 analysis; it was free from visible lamellae, although it may have 

 contained indistinguishable ones. Its composition proved to 

 be: CaO 6.30, CuO 1.25, MgO 0.80, 3 A1 2 3 25.90, Fe 2 3 2.14, 

 P 2 5 24.76, Si0 2 7.32, H 2 below 100° 21.90, above 100° 9.20, 

 sum 99.57. These figures lead to no simple formula, but as it 



1 Published by permission of the Secretary of the Smithsonian Institution. 



2 U. S. National Museum Catalogue No. 92909. 



3 Determined by the writer on a separate sample. 



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