Acta naturalia Islandica - 01.07.1964, Síða 36

PLATE II.
Pl. II a. Plagioclase phenocryst with a core of uniform composition and a zoned
mantle, The core is occupied by cubes of magnetite. Crossed nicols x 50.
Pl. II b. Pyroxene phenocrysts in a granular groundmass. The large phenocryst shows
an opeD cavity thought to be due to skeletal growth. The outer rim is well seen and
the plagioclase zone next to the phenocryst. The black spots are iron ore. Plane pola-
rized light x 15.