WATSON AND WHERRY: PYROLUSITE FROM VIRGINIA 555 



from India. No reference is made in the description by Fermor 

 that the pyrohisite crystals represented by the two analyses are 

 of pseudomorphous origin, but are tabulated by him as "Analyses 

 of Indian pyrolusites," the present writer assuming that they are 

 not pseudomorphous after manganite. Both analyses contain 

 around 0.5 per cent each of manganous oxide and combined 

 water, which are less than for pseudomanganite (analysis V) and 

 for the Virginia pyrolusite (analyses I and II). In the same 

 table Fermor gives a detailed analysis of "a piece of the radiate- 

 concentric pyrolusite of Pali in the Nagpur district," which 

 shows 0.41 per cent and 1.46 per cent respectively of MnO and 

 combined H2O, and specific gravity 4.88. Again the writer as- 

 sumes this analysis to represent pyrolusite of nonpseudomor- 

 phous origin. 



On comparing the analyses (I and II) of Virginia pyrolusite 

 with the analysis (V) of pseudomanganite from India, it will be 

 noted that the percentages of manganous oxide and combined 

 water are in fairly close agreement. The same is true for the 

 minor constituents, except that MgO present in pseudomanganite 

 is absent from, the Virginia pyrolusite; this, however, has no 

 significance. Fermor^ states that the pseudomanganite presents 

 considerable differences in physical characters from pyrolusite 

 but shows considerable resemblances to manganite, though 

 chemically close to pyrolusite. The name pseudomanganite as 

 proposed by Fermor is therefore not applicable to the Virginia 

 mineral (pyrolusite crystals, analysis I, and crystalline pyrolusite, 

 analysis II), since, as shown above, it resembles pyrolusite and 

 not manganite both chemically and physically. 



It seems entirely clear, on the basis of chemical composition 

 and physical characters, that if the crystals of manganese oxide 

 from Virginia (analysis I) are of pseudomorphous origin after 

 manganite, the associated crystalline fibrous mineral (analysis 

 II) must also be of the same origin. Certain of the facts devel- 

 oped in this study, especially the crystallography (abnormal 

 axial ratio and habit for manganite) are, however, not in har- 



' Fermor, L. Leigh. O-p. cil., p. 84. 



