. Bulletin of the Department of Geology of the University of California. Lawson.] Geology of Carmclo Bay. 11 some attained a size of mm., and one was found to be as much as 3 mm. in greatest length. Of these inclusions the feldspars usu- ally present sharply idiomorphic forms, and are frequently twinned. The quartzes occur prevailingly in rounded bleb-like crystals, some- times angular, and recall the rounded quartzes of the quartz- porphyries. The biotite has the form of thick little plates, which show sometimes hexagonal sections. The muscovite occurs in ragged,shred-like patches. Minute
. Bulletin of the Department of Geology of the University of California. Lawson.] Geology of Carmclo Bay. 11 some attained a size of mm., and one was found to be as much as 3 mm. in greatest length. Of these inclusions the feldspars usu- ally present sharply idiomorphic forms, and are frequently twinned. The quartzes occur prevailingly in rounded bleb-like crystals, some- times angular, and recall the rounded quartzes of the quartz- porphyries. The biotite has the form of thick little plates, which show sometimes hexagonal sections. The muscovite occurs in ragged,shred-like patches. Minute slender needles,probably apatite, also occur in the phenocrysts, but these are scattered in all directions and do not appear to have any definite relation, as to their orien- tation, to their Figure 2.—Section of orthoclase phenocryst ot Santa Lucia granite, parallel to basal pinacoid (001), showing inclusions of quartz, q; felds- par, f; biotite, b; and muscovite, m. All the quartzes have a common orientation, with the optic axis perpendicular to the basal pinacoid of the host; and the feldspars have a common orientation by groups, x 8. The orientation of the quartzes and feldspars is very remarkable. Not only are these minerals distributed in their host in definite. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original University of California, Berkeley. Dept. of Geology. Berkeley : The University
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