MISER AND FAIRCHILD: HAUSMANNITE 7 



"With fluxes it gives manganese reactions; it dissolves in hydro- 

 chloric acid with the evolution of chlorine. 



"The following analysis was made mostly by Dr. R. N. Brackett and 

 partly by Prof. W. A. Noyes. It shows the composition of the mineral 

 dried at iio°-ri5° Centigrade. 



"Analysis of Braunite from the Batesville Region 



Per cent Ratio 



Manganese protoxide (MnO) 87 .47 i . 232 2 .05 



Oxygen (O) 9 . 62 o . 601 i . 00 



Ferric oxide (FcaOs) o ■ 44 



Alumina (AI2O3) o . 11 



Lime (CaO) o . 34 



Baryta (BaO) o . 48 



Magnesia (MgO) Trace 



Potash (K2O) o . 10 



Soda (NaaO) -. 0.05 



Phosphoric acid (P-Oi) 0.25 



Silica (SiOj) 0.18 



99.04 



"It will be observed that the ratio of MnO to O is almost exactly 

 as 2:1, which is the theoretical ratio of manganese sesquioxide 

 (Mn203). It will also be noticed that the analysis shows less than 

 2 per cent of ingredients other than MnO and O, and the mineral is 

 therefore a very pure Mn203. Though the mineral occurs as a com- 

 pact crystalline aggregate and not as isolated crystals, it seems, judging 

 from its general appearance and its physical characteristics, to be 

 homogeneous. In some other specimens of a similar material there 

 were found some very small crystals, apparently tetragonal pyramids, 

 suggesting, from their general form, that they might be braunite. 

 Hausmannite crystallizes in the same system, but the above analysis 

 does not show any close relation to the composition of that mineral. 

 The analysis shows a mineral resembling in all respects a braunite 

 without silica, and the physical features of the specimen, as far as they 

 can be distinguished, are also those of braunite." 



Fermor,'' in his report on the manganese-ore deposits of India, 

 says that only two published analyses, that have not been 

 checked by further analyses, show braunite to correspond to the 

 formula MnoOs. One of these is the above analysis given by Pen- 

 rose and the other is an analysis by Bechi of a specimen from the 

 island of Elba.^ Fermor continues, "But it is to be noticed that 

 another analysis of Arkansas braunite [from the Batesville dis- 

 trict] shows 9.97 per cent of Si02, the analysis being by W. 



* L. L. Fermor. The manganese-ore deposits of India. Memoirs Geol. Survey 

 India. 37: pt. i, 64. 1909. 



" Meneghini, Mineralogical notices. Amer. Journ. Sci. [2] 14: 62. 1852. 



