California, Oregon and Washington Territory. 229 
glass with much larger microlites of feldspar and pyroxene and 
magnetite. ‘T'he minuteness and intimate association of the 
_ the microscope shows that the hypersthene was the first of the 
atter were subjected to the Thoulet solution in order to com- 
pletely isolate the glass from feldspar. An amount of glass 
Specific gravity as to the impurities in the crystals, so that a 
labradorite rich in glass inclusions might readily be of less 
