1 
2 A : fi : 
Figszand2. Diabase or gahbhro from coast of Lake Supertor, near Beaver Bay, Minn. fie g.1. ordinary 
light. Frg2 polarzzer leght Scale 21 diameters 
Anorthi tet; augetel2 J, 
Figs.s andy. Gabbro from coast of Lake Supercor near Duluth, Minn Fug.8 orcdenary Light, Arg. 4 
polarzzect leght. Scale so diameters 
Anorthitet/; deatlagze exugrte(2/, trlencferous magnetite (9); trom oxcale (4/ 
