Weed and Pirsson — Bearjpaw MountaAns^ Montana. 147 





I. 



11. 



III. 



IV. 



V. 



la. 



SiO, .--... 



. 46-51 



48-12 



47-53 



54-42 



47-28 



•775 



Al.O^ 



. 11-86 



17-16 



1949 



13-37 



11-56 



•115 



FeA .._- 



. 7-59 



5-69 



2-04 



-61 



3-52 



-047 



Feb - 



. 4-39 



5-13 



5-24 



3-52 



5-71 



•061 



M^O 



. 4-73 



3-99 



4-10 



6-37 



13-17 



•118 



CaO 



. 7-41 



9-84 



10-09 



4-38 



9-20 



•132 



Na,0 



. 2-39 



2-77 



2-67 



1-60 



2-73 



•038 



K,6 



. 8-71 



7-24 



7-12 



10-73 



2-17 



•092 



H^O-110° 



1-10 















H 0+110° 



2-45 



•08 



•48 



2-76 



2-96 





TiO, 



-83 



-22 



-25 



? 



•88 





Fl.. 



. trace 



none 



none 













CI 



-04 



not det. 



not det. 







•18 





SO3 



. trace 



















PA 



-80 



trace 



•19 



? 



•59 





CO, 















1-82 



. _ - - 





CuO 



.str. tr. 





. .. - - 











NiO 



-04 





















CoO 



str. tr. 





















MnO 



-22 



1-20 



1-18 







•13 





BaO 



•50 



? 



? 



? 



? 





SrO 



•16 



? 



? 



? 



9 





CrA ----- 



none 







.... 















99-73 



101-44 



100-38 



99-58 



100-08 





o=ci 



-01 













99-72 



I. Leucitite, Bearpaw Mountain, Montana, H. N. Stokes anal. 



II. Leucite basanite, Vesuvius 1631 (Trans. Roy. Irish Acad., 

 vol. xxvi, p. 50, 1876), S. Haughton anal. 



III. Leucite tephrite, ibid (ibid, p. 83), ibid. 



IV. Leucitite, Leucite Hills, Wyoming (Emmons Surv, 40th 

 Par., vol. ii, Descrip. Geol. 1877, p. 237), R. W. Woodward anal. 



V. Leucite absarokite, Ishawooa Canyon, Wyoming (Hague, 

 this Jour., vol. xxxviii, 1889, p. 47 ; Iddings, Jour. Geol., vol. iii, 

 1895, p. 938), J. E. Whitfield anal. 



la. Molecular proportions of analysis I. 



The marked features of this analysis are the low alumina 

 and silica and the very high potash, peculiarities which 

 sufficiently explain the presence of the leucite. IN^eglecting 

 the very small amount of biotite and glass present, the essen- 

 tial minerals are iron ore, augite, and leucite, and considering 

 the molecular proportions given in la these become 



