4 MISER AND FAIRCHILD: HAUSMANNITE 



road, and Sample No. 2 was from the Club House mine, one-half 

 mile north of the town of Cushman on another spur of the same 

 railroad. The specimens from which the samples were prepared 



TABLE I 

 Analyses of Hausmannite from the Batesville District 



No 1 No. 2 



Manganese protoxide (MnO) 91 38 90 . 40 



Oxygen (O) 7-78 8 . 87 



Iron oxide (Fe203) None 



Alumina (AI2O3) None J 



Silica (Si02) None o . 10 



Lime (CaO) Trace Trace 



Magnesia (MgO) Trace Trace 



Baryta (BaO) o. 26 None 



Total water (H2O) 0.62 i . 03 



Summation 100.04 100.88 



Manganese (Mn) 70 . 76 70 . 00 



Specific gravity at 15.5° C 4836 4-778 



No. I . Sample from W. T. Gray mine. 

 No. 2. Sample from Club House mine. 

 '' Includes a trace of iron. 



for the analyses contain a small quantity of psilomelane and for 

 this reason the samples were carefully selected, using a pocket 

 lens, so as to free the hausmannite as far as possible from the 

 psilomelane. Polished surfaces of these specimens, however, 

 show the presence of psilomelane as fine, disseminated particles 

 and as crack-filling material too minute to be observed by a pocket 

 lens on a rough fractured surface. Some psilomelane was there- 

 fore present in the samples and the polished surfaces indicate 

 that there was more of it in Sample No. 2 than in Sample No. i. 

 There are several varieties of psilomelane, which may be con- 

 sidered to be a manganese manganate, MnoMnOs, otherwise 

 expressed as 2Mn02.MnO. In the fundamental formula, the 

 "Muo" may be replaced by such equivalent groups as Bao, 

 Cao, K4, H4, etc. The ratio of MnO to available oxygen, which 

 is here called the ' 'oxygen ratio, ' ' is, according to the above formula, 

 3 to 2, or expressed more simply; 1.5. The composition shows 

 13. 1 per cent available oxygen. The oxygen ratio for haus- 

 mannite (Mn304) is 3, its composition showing 7.0 per cent avail- 



