654 



FRANK F. GROUT 



that this material is not a mixture of orthoclase and another mineral. 

 No other mixture seems to fit the case and although the analyses show 

 considerable variation it is quite certain that we are dealing with 

 material not hitherto described. At least, it is a new alteration prod- 

 uct for laumontite. It is here proposed that the new mineral be 

 called pseudo-laumontite. Chemically it is unique in combining 

 potassium and magnesium in a silicate. The rock-analysis No. 5, of 

 Table I, resembles the analyses of pseudo-laumontite closely enough 

 to be of interest in this connection. 



TABLE VII 

 Analyses of Miscellaneous Amygdltles 



1. Orthoclase, fine-grained, salmon-pink tufts lining cavities, T.39N., R.21W., 

 Pine City, Minn. F. F. Grout, analyst. 



2. Analcite, red and white mottled crystals, associated with either laumontite or 

 orthoclase, Pine City, Minn. F. F. Grout, analyst. 



3. Prehnite, radiating groups in a light-green vein-filling, T.41N., R.20W., Kettle 

 River, near Hinckley, Minn. F. F. Grout, analyst. 



4. Datolite, enamel-like bunches, associated with chlorite in cavities. Pine City 

 Minn. F. F. Grout, analyst. 



5. Chalcedony, Crooked Creek, Pine Co., Minn. F. F. Grout, analyst. 



* The percentage of silica in chalcedony and of boric acid in datolite are found "by difference." The 

 difficult method of estimating boric acid gave the analyst 17.36 per cent BaOa instead of 18.88. Material 

 was exhausted before it was satisfactorily checked. 



Several other minerals have been tested, chiefly by analysis, to 

 estimate their purity. Analcite yielded measurable crystals of the 

 common form. All of the mineral occurrences recorded with the 



