porphyroblast


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Related to porphyroblast: Porphyroblastic Texture, Euhedral

por·phyr·o·blast

 (pôr-fîr′ə-blăst′)
n.
A large crystal that is surrounded by a fine-grained matrix in a metamorphic rock and forms from the recrystallization of existing mineral crystals during metamorphism.

[porphyr(y) + —blast.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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References in periodicals archive ?
A texturally zoned porphyroblast is herein defined as any porphyroblast that contains included and relatively clear, inclusion free (or poor) zones (Fig.
Multiply deformed and metamorphosed rocks commonly preserve a record of lengthy periods of deformation and associated several phases of porphyroblast growth.
Where possible, to assess the reliability of calculated peak P-T conditions, the fractionation of major cations from the matrix during porphyroblast growth was modelled in THERMOCALC.
Preservation of such a detailed record of punctuated porphyroblast growth and microstructural evolution is rare along the length of the Himalaya.
The late schistosity in the sedimentary rocks, defined by muscovite and biotite, wraps around cordierite porphyroblasts, which contain relicts of the earlier phyllitic cleavage (Thorne and Lentz 2001; Park et al.
The amphibolite is porphyroblastic and contains porphyroblasts of hornblende.