i8 



J. SCHETELIG. 



I.-N. Kl. 



Fig. 6. Rock-specimens from Scott's Nunataks, showing the border of biotite along the 

 junction between pegmatite and amphibolite. (Natural size.) 



Under the microscope the orthodase shows microperthitic spindules of 

 albite and is often altered into rnicrocline. Along the borders of the 

 sections occur rounded and irregular shapes of myrmekite, formed at the 

 expense of orthoclase. 



Fig. 7. Pegmatite. Scott's Nunataks. Labradorite, biotite, quartz and apatite from the 

 "Sahl-band". Micro-Photo. Niçois +. Enlarg. 17. 



