groundmass

Definitions

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

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

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

ground +‎ mass

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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 greygirlbeast 2010
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 greygirlbeast 2010
[Small, separated mineral crystals in a glassy groundmass]

Boing Boing 2008
Immersed in this groundmass are a wide variety of rock shapes, sizes, textures—round and angular—many with varying consistencies.

First Man James R. Hansen 2005
The groundmass throughout the area is a very fine sand to a silt.

First Man James R. Hansen 2005
Immersed in this groundmass are a wide variety of rock shapes, sizes, textures—round and angular—many with varying consistencies.

First Man James R. Hansen 2005
The groundmass throughout the area is a very fine sand to a silt.

First Man James R. Hansen 2005
The groundmass throughout the area is a very fine sand to a silt.

First Man James R. Hansen 2005
Immersed in this groundmass are a wide variety of rock shapes, sizes, textures—round and angular—many with varying consistencies.

First Man James R. Hansen 2005
The groundmass throughout the area is a very fine sand to a silt.

First Man James R. Hansen 2005