MINERALOGY, 125 



perhaps, than elsewhere in the United States. It occurs in the great 

 granite vein; and in blasting for mica, large pieces of it, some of which 

 weigh more than fifty pounds, have been thrown out. Mr. M. A. Brown 

 reports that he obtained blocks of the pure mineral as large as water- 

 pails. It is light blue in color, possesses a resinous lustre, and cleaves 

 very well parallel to the base of its orthorhombic crystals, though the 

 form of its crystallization cannot be determined from any faces that the 

 mineral presents. The exterior of the masses and the cleavage surfaces 

 are often blackened by the decomposition, which might be expected in a . 

 mineral so rich in protoxides of manganese and iron. A careful analysis 

 of this triphylite from Grafton has been made by Mr. S. L. Penfield,* of 

 the Sheffield laboratory, which is as follows: 



I. II. 



Phosphoric anhydride, ...... 44.18 43 -88 



Iron protoxide, 26.09 26.38 



Manganese protoxide, ...... 18.17 18.24 



Lime, .89 .99 



Magnesia, .56 .61 



Lithia, . • 8.77 8.81 



Potash, .32 .32 



Soda, .16 .09 



Water, 1.47 1-47 



100.61 100.79 



From this analysis, which is the first that has been made on an Amer- 

 ican triphylite, Mr. Penfield calculates that the right formula is R^ P 

 O' + R' P O^ (R standing for univalent elements, and R for the bivalent), 

 a formula suspected by Rammelsberg to be the correct one, but to which 

 no previous analysis has so closely approximated. Mr. Penfield points to 

 the circumstance that our mineral is richer in manganese and lithia than 

 the Bavarian mineral, which has been the chief subject of previous in- 

 vestigation. 



SCORODITE WaVELLITE. 



Scorodite, the hydrous arsenate of iron, has been reported as found at the Jackson 

 tin mines. Its occurrence is doubtful, Wavellite is put in some lists of mineral local- 

 ities as occurring at Bellows Falls. Mr. Downs, of Lebanon, says that it is not to be 



* Am. your. Science, iii, vol. xiii, p. 425. 



