Definitions

from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun 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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun geology A relatively large crystal within a metamorphic rock

Etymologies

from The American Heritage® Dictionary of the English Language, 4th Edition

[porphyr(y) + —blast.]

Examples

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Comments

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  • (n): (geology) in metamorphic rocks, a mineral crystal that is much larger than the crystals of the enclosing or surrounding matrix.

    January 2, 2009