The Geology and Petrography of Crater Lake National Park, 1902
PART II.
BASALTS.
INTERSTITIAL BASALTS.
HYPERSTHENE, APATITE, AND PSEUDOBROOKITE CRYSTALS IN BASALT.
APATITE CRYSTALS.
Apatite occurs in very delicate, minute, slender needles. The identification as apatite rests upon the needle form and the fact that they possess very low double refraction and have parallel extinction with negative extension.
The unknown white crystals occur in abundant, roundish forms which, when broken, are seen to be aggregates. It is possible that they are tridymite, with which they have some resemblance, but this could not be proved.
Below is submitted the report on hypersthene and pseudobrookite crystals by Dr. C. Palache.
