438 J. H. L. VOGT 
As an example we refer to Figures 20 and 21 and to 
Figure 13, microscopic photograph of a norite from Skougen in 
Bamle, Norway. This rock consists, according to microscopic 
investigations supported by chemical analysis (see Part II), of 
about 47 per cent hypersthene (according to the analysis of the 
Frc. 14.—Anorthosite from Hitteré, Norway. The labradorite (Ab,An,, light) 
has idiomorphic contours against the hypersthene. (25: 1.) 
rock and the optical determination calculated as 0.32 FeSiQ;: 
0.68 MgSiO,), a trifle secondary hornblende, 48 per cent labra- 
dorite (ca. 38 Ab, 4 Or, 58 An, or about Ab.An;), 3 per cent biotite, 
and 1-2 per cent magnetite-ilmenite, see later (Figs. 31-32), 
0.07 per cent apatite, and a little pyrite (o.24 per cent S). 
On the other hand, in rocks especially rich in plagioclase we 
find throughout the idiomorphism more or less well developed by 
the plagioclase, but not by the pyroxene. This applies to all 
anorthosites which I have investigated, where the ferromagnesian 
er APES See GS 
