252 REPORT OF NATIONAL MUSEUM, 1899. 



Chrome Iron Ore from Orsova. 



Journal of the Iron and Steel Institute, 1889, p. 316. 

 Chrome Iron, Shasta County. 



Tenth Annual Report of the State Mineralogist of California, 1890, p. 638. 

 Chromium in San Luis Obispo County. 



Tenth Annual Report of the State Mineralogist of California, 1890, p. 582. 

 Chrome Iron in New Zealand. 



Engineering and Mining Journal, LIV, 1892, p. 393. 

 Chromic Iron. 



Twelfth Report of the State Mineralogist of California, 1894, p. 35. 

 J. T. DONALD. Chromic Iron in Quebec, Canada. 



Engineering and Mining Journal, LVIII, 1894, p. 224. 

 Chromic Iron: Its Properties, Mode of Occurrence and Uses. 



Journal of the General Mining Association of the Province of Quebec, 1894-95, 

 p. 108. 

 W. F. WILKINSON. Chrome Iron Ore Mining in Asia Minor. 



Engineering and Mining Journal, LX, 1895, p. 4. 

 WM. GLENN. Chrome in the Southern Appalachian Region. 



Transactions of the American Institute of Mining Engineers, XXV, 1895, p. 481. 

 Chromic Iron. 



Thirteenth Report of the State Mineralogist of California, 1896, p. 48. 

 GEORGE W. MAYNARD. The Chromite Deposits on Port au Port Bay, New Foundland. 



Transactionsof theAmericanlnstituteof Mining Engineers, XXVII, 1897, p. 283. 

 J. H. PRATT. Chromite in North Carolina. 



Engineering and Mining Journal, LXVII, 1899, p. 261. 



The Occurrence, Origin, and Chemical Composition of Chromite, with especial 



reference to the North Carolina Deposits. 



Transactions of the American Institute of Mining Engineeers, XXIX, 1899, 

 p. 17. 



10. MANGANESE OXIDES. 



The element manganese exists in nature under many different forms, 

 of which those in combination as oxides, carbonates, and silicates 

 alone need concern us in this work. The principal known oxides 

 are manganosite (MnO); Hausmanite (MnO,Mn 2 O 3 ); Braunite 

 (3Mn 2 O 3 , MnSiO 3 ); Polianite (MnO 2 ) ; Pjrolusite (MnO 2 ); Manganite 

 (Mn 2 O 3 ,H 2 O); Psilomelane (H 4 MnO 5 ); and Wad, the last being, perhaps, 

 an earthy impure form of psilomelane. To this list should be added 

 the mineral f ranklinite, a manganiferous oxide of iron and zinc. Of 

 these the first named, manganosite, is rare, having thus far been reported 

 only in small quantities associated with other oxides in Wermland, 

 Sweden. The other forms are described somewhat in detail as below. 

 It should be stated, however, that with the exception of the well- 

 crystallized forms it is often diflacult to discriminate between them, as 

 they occur admixed in all proportions, and, moreover, one variety, 

 as pyrolusite, may result from the alteration of another (manganite). 

 The better defined species may be separated from one another by their 

 comparative hardness, streak, and hydrous or anhydrous properties, as 

 shown in the accompanying table. 



