Definitions

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

  • noun The fine-grained crystalline base of porphyritic rock in which larger crystals are embedded.

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

  • noun geology The matrix of fine-grained crystalline material in which larger crystals are embedded.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun (geology) the matrix of fine-grained crystalline material in which larger crystals are embedded

Etymologies

from Wiktionary, Creative Commons Attribution/Share-Alike License

ground +‎ mass

Examples

  • The rock here is a porphyritic granite (porhyritic meaning that the stone has large-grained crystals, such as feldspar or quartz, dispersed in a fine-grained feldspathic matrix or groundmass).

    Of Books and the Sea

  • The rock here is a porphyritic granite (porhyritic meaning that the stone has large-grained crystals, such as feldspar or quartz, dispersed in a fine-grained feldspathic matrix or groundmass).

    Of Books and the Sea

  • [Small, separated mineral crystals in a glassy groundmass]

    Boing Boing

  • Immersed in this groundmass are a wide variety of rock shapes, sizes, textures—round and angular—many with varying consistencies.

    First Man

  • The groundmass throughout the area is a very fine sand to a silt.

    First Man

  • Immersed in this groundmass are a wide variety of rock shapes, sizes, textures—round and angular—many with varying consistencies.

    First Man

  • The groundmass throughout the area is a very fine sand to a silt.

    First Man

  • The groundmass throughout the area is a very fine sand to a silt.

    First Man

  • Immersed in this groundmass are a wide variety of rock shapes, sizes, textures—round and angular—many with varying consistencies.

    First Man

  • The groundmass throughout the area is a very fine sand to a silt.

    First Man

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