530 TAT VOGE 
the same manner as the plagioclase in the gabbro rocks which are 
especially rich in hypersthene or diallage—a mass of putty or a 
Zwischenklemmungsmasse (mesostasis) between the ferromagnesian 
silicate minerals. 
So we arrive at the result that in the rock in question, with 
little. olivine and predominant hypersthene, with monoclinic 
pyroxene and some hornblende, the olivine belongs to the last 
stage of crystallization. 
Fic. 25.—Photomicrograph (24:1) of olivine-bearing hypersthenite with some 
diallage and hornblende, from Nonaas, Hosanger, Norway. The light-gray mineral 
is hypersthene with some diallage, the dark-gray is hornblende, and the white olivine. 
Also in some other olivine-bearing pyroxenites, moderately 
rich in iron, with predominant hypersthene, or diallage or both, 
and in addition with only a quite small amount, say Io or 15 per 
cent, of olivine, the structure proves the late commencement of 
the crystallization of the olivine. 
If we pass on to the dunites and saxonites poor in iron, usually 
with 40-43 per cent SiO,, 42-48 MgO, 7-10 FeO, o-1.5 CaO, and 
