Fics. 2. and 3.—Photomicrographs of thin-sections of gabbro from stock No. 4 
(see accompanying map). Each magnified 15 diameters. 
In the upper figure the large central mineral is olivine completely surrounded 
by successive rims of hypersthene, biotite (narrow and dark), and garnet. Surround- 
ing all are broad laths of labradorite. 
In the lower figure the large, black, central mineral is ilmenite followed by suc- 
cessive rims of biotite, hornblende, garnet, and biotite. The second and third— 
biotite and hornblende—rims are not separable in the photograph. Surrounding 
all are labradorite crystals. 
