microporphyritic

microporphyritic

[¦mī·krō‚pȯr·fə′rid·ik]
(petrology)
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The two summits of the hill defined by the Logrosan granite (the San Cristobal hill) are composed of a microporphyritic (two-texture) granite and an aplitic granite (Evolved Units) (Fig.
A total of 9 representative samples weighted between 3-5 kg were collected for whole-rock geochemistry (6 medium to coarse-grained granites from the Main Unit and 3 fine-grained or microporphyritic granites from the Evolved Units) (Table 1).
Thin sections of dyke contacts show microporphyritic crystals of plagioclase, augite, and orthopyroxene scattered in a dark glassy matrix (Fig.
The mineralization is associated with intense montmorillonite-quartz-carbonate-pyrite alteration developed in a microporphyritic andesite.
The rhyolite occurs as aphanitic to porphyritic flows and ignimbritic tuffs with flow banding and microporphyritic to porphyritic textures (Fig.
The significance of flow structure in microporphyritic ophitic basalts of Arthurs Seat.
Lavas are commonly amygdaloidal and/or microporphyritic with phenocrysts of feldspar and, more rarely, pyroxene or quartz, set in a glassy to microcrystalline groundmass.