W, T. SchalleT — Ludwigite from Montana. 



147 



Analysis of Ludwigite frotn Montana. 



Analysis of ludwigite mixed with forsterite 

 and carbonate. 



12 3 Average 



FeO.. 6-12 5-53 5-74 5-79 



MgO 39-09 38-60 39-42 39'04 



Total iron 36-33 36-01 



Ye„0^ 29-73 



SiO, 8-97 8-74 8-85 8-85 



Al^O, 1-98 J-64 1-81 



H,0+ -97 -97 



H^— -91 -95 -85 -90 



CO, -28 -43 -36 



BO 13-48 13-48 



Analysis of 

 ludwigite. 



7-27 

 33-78 



37-37 



2-27 

 1-24 

 1-13 



16-94 



100-93 



100-00 



of the iron witli permanganate solution. The iron and 

 aluminum chloride solution was repeatedly evaporated with 

 methyl alcohol to expel all the boric acid. The second value 

 (1-64: per cent) was determined by precipitating the alumina 

 by phenylhydrazine, as described by Allen.* As the two 

 determinations agree fairly well, the presence of a small 

 amount of alumina in the sample seems well confirmed. The 

 higher result of the first case is probably due to the retention 

 of a small amount of boric acid. Whether the alumina belongs 

 to the ludwigite or to one of the accompanying minerals is 

 difiicult to decide, but it has here been included in the borate. 

 The boric acid content has also been determined by Wherry 

 and Chapin,f who give as the average of their results 12-82 

 per cent B^O^, a value slightly lower than the one here given. 

 The water content, though small, is still of sufficient 

 importance to merit consideration. While no definite con- 

 clusion has been reached, it is believed that most, if not all, of 

 the water is really unessential to the mineral. The determi- 

 nations were made on the finely ground material and consider- 

 able water was thereby unquestionably taken up by the 

 mineral.:]: As some water may also have been furnished by 

 the secondary fibrous material, it therefore seems justifiable to 

 conclude that a good part, if not all, of the water reported 

 in the analysis is extraneous. It has been entirely omitted 

 in the consideration of the ratios deduced from the analyses. 



« Journ. Amer. Chem. Soc, vol. xxv, p. 431, 1903. See also Bull. 305, 

 U. S. Geol. Survey, p. 95. 



f Determination of Boric Acid in Insoluble Silicates, E. T. Wherry and 

 W. H. Chapin. Journ. Amer. Chem. Soc, vol. xxx, p. 1691, 1908. 



X For data on this point, see this Journal, vol. xxv, p. 338, 1908. 



