No. 2395. LVDWIGITES FROM IDAHO AND KOREA— SHANNON. 



673 



of a magnesia member free from ferrous iron, this molecule being in 

 excess in the Montana material and having the formula 

 3MgO.B 2 3 .MgO.Fe 2 3 . 



MAGNESIOLUDWIGITE, UTAH. 



Magnesioludwigite, the magnesia end-member of the ludwigite 

 group predicted by Schaller from his work on the Montana ludwigite, 

 was found by Butler in nearly pure form in the Mountain Lake mine 

 in Utah 12 . The material is ivy-green in color and it occurs in a con- 

 tact metamorphosed limestone with ordinary ludwigite, magnetite, 

 etc. 



LUDWIGITE, UTAH. 



Ludwigites which are apparently ordinary in composition and 

 contain ferrous iron have been found in several localities in the 

 Cottonwood-American Fork area in Utah 13 . The mineral occurs in 

 large amounts mixed with magnetite and lime silicates in contact 

 metamorphosed limestones. The material from these occurrences 

 has not been analyzed. 



VONSENITE, CALIFORNIA. 



Vonsenite, described by Eakle u from Riverside County, California 

 is a member of the ludwigite group which is much higher in iron than 

 other members of the group, even the pure ferroludwigite end member 

 as is shown by the following comparison: 



Ferrolud- 

 wigite, 

 theory. 



B 2 3 

 Fe 2 

 MgO 



FeO. 



100.0 



The material occurs with magnetite in contact zones in limestone. 



GENERAL DISCUSSION. 



The above descriptions include all known occurrences of the 

 minerals of the ludwigite group. The compositions of those which 

 have been analyzed may be expressed by the following formulas : 



Ludwigite (ferroludwigite), Hungary. 3MgO.B 2 3 .FeO.Fe 2 3 . 



Magnesioludwigite, Utah 3MgO.B 2 3 .MgO.Fe 2 3 . 



Pinakiolite, Sweden 3MgO.B 2 3 .MnO.Mn 2 3 . 



Vonsenite, California 3(Fe,Mg)O.B 2 3 .FeO.Fe 2 3 . 



Ludwigite, Montana 3MgO.B 2 3 .(Mg,Fe)O.Fe 2 3 . 



Ludwigite, Idaho 3MgO.B 2 3 .(Mg,Fe)O.Fe 2 3 . 



Ludwigite, Korea 3MgO.B 2 3 .(Fe,Mg)O.Fe 2 3 . 



u Butler, B. S., and Schaller, W. T., Magnesioludwigite, a new mineral. Wash. Acad. Sci. Journ., vol. 

 7, No. 2, pp. 29-31, 1917. 

 « Butler, B. S., Ore Deposits of Utah. Prof. Paper U. S. Geological Survey, no. Ill, p. 243, 1920. 

 m Eakle, Arthur S., Vonsenite, a preliminary note on anew mineral. Amer. Mineral., vol. 5, p. 141, 1920. 



27177— 21— Proc.N.M.vol.59 43 



