DESCRIPTION OF PLATE. 
Figs. 1-4. Zonai-y feldspars from black diabase north east of Duluth. 
Outer zone orthoclase or oligoclase, inner zone labradorite, with amor- 
phous zone between. 
Fig. 5. Section from norjte near Marshall, N. C; Z^, bronzite showing 
both cleavage systems. The fine lines are parallel i-i, in which zone lies 
the interpenetrating lamella; o^ olivine; y", labradorite feldspar. 
Fig. 6. Portion of the same section showing occurrence of biotite (w) 
about the magnetite; o, olivine; c?, apatite; r//, chlorite; /, plagioclase. 
Fig. 7. Portion of same section illustrating the occurrence of the 
magnetite; w, biotite mica; /, plagioclase. Granular decomposition pro- 
duct filling interstices. 
Fig. 8. Portion of section from diabase of Duluth; r?, augite;(//, apa- 
tite ; _/", feldspar. 
Fig. 9. Crystals of garnet ij') from dioryte adjacent to noryte of figs. 
.5-7- 
Fig. 10. Feldspar paragenesis in so-called orthoclasegabbro of Du- 
luth ; c/, diallage. 
