Definitions
from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun A conspicuous, usually large, crystal embedded in porphyritic igneous rock.
from The Century Dictionary.
- noun One of the prominent crystals in a porphyritic rock.
from the GNU version of the Collaborative International Dictionary of English.
- noun (Geol.) One of the prominent embedded crystals of a porphyry.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun mineralogy any relatively large
crystal embedded in a more fine-grained or glassyigneous rock
Etymologies
from The American Heritage® Dictionary of the English Language, 4th Edition
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Examples
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Fig. 9 (A, B) shows an MI believed to have formed as a two-phase mixed inclusion (melt + fluid) within a quartz phenocryst of peralkaline rhyolite (Lowenstern et al. 1991).
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Quartz in groundmass does not appear to have nucleated directly on phenocryst, but is in optical continuity with it. (f) Primary vapor-rich fluid inclusion in phenocrystic quartz.
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Radiating fringe of feldspar in groundmass is in optical continuity with phenocryst, from which it nucleated. (e) Quartz phenocryst is surrounded by feldspar groundmass.
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Figure parts a-e with crossed nichols. (a) Micrographic groundmass surrounds feldspar phenocryst fragment. (b) Micrographic groundmass around clinopyroxene phenocryst.
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