schallee: purpurite and heterosite 113 



groups being as follows: Sulphates [R'" (OH) 2 ] 6 .R".[S0 4 ] 2 . [S0 4 ] 2j 

 Phosphates, [R'" (OH) 2 ] 6 .R". [HP0 4 1 2 . [R"(P0 4 ) 2 ] and Phos- 

 phate-sulphates [R'"(OH) 2 ] 6 .R". [S0 4 ] 2 .[R"(P0 4 ) 2 ]. In the sul- 

 phate sub-group, R' 2 replaces R" in most cases or else two uni- 

 valent alkali metals, such as (K 2 ) may be considered equivalent 

 to R". Of the acid radicles the bivalent group =[S0 4 ] 2 is consid- 

 ered as isomorphous with the bivalent group = [HP0 4 ]. 



MINERALOGY. — The relations of purpurite and heterosite. 

 Waldemar T. Schaller. To appear in Bulletin 490, U. 

 S. Geological Survey. 



The mineral purpurite, a hydrous manganic ferric phosphate, 

 (Mn, Fe) 2 3 .P 2 5 .H 2 0, was first found in North Carolina, by 

 L. C. Graton, and a description of it was published 1 in 1905. 



Since the original discovery the same mineral has been found at 

 other localities 2 (South Dakota, Connecticut). Lacroix, 3 to whom 

 some of the original purpurite from North Carolina was sent, has 

 stated that purpurite is identical with heterosite. In view of this 

 I propose that the name heterosite be restricted to the ferric 

 phosphate and the name purpurite to the manganic phosphate. 

 Heterosite predominates (76 per cent) in the material from South 

 Dakota while purpurite predominates (65 per cent) in that from 

 North Carolina. More accurately the North Carolina material 

 should be called iron (or ferric) purpurite and that from South 

 Dakota and from France, manganese (or manganic) heterosite. 



In the original paper describing purpurite the suggestion was 

 made that the pure end members could be called ferripurpurite 

 and manganipurpurite. Since, however, the identity of the min- 

 eral with the French heterosite has been advocated by Lacroix, 

 the names ferripurpurite and manganipurpurite should be replaced 

 by the older names heterosite and purpurite respectively. 



1 Graton, L. C, and Schaller, W. T.: Purpurite, a new mineral. Am. Jour. 

 Sci., 4th ser., 20: 146. 1905. 



2 Schaller, W.T.: Mineralogical Notes, — 1. Purpurite from two new localities. 

 Am. Jour. Sci., 24: 1.52. 1907. 



3 Lacroix, A.: Mineralogie de la France, 4: 469. 1910. 



