- the crystalline, granular, or glassy base or matrix of a porphyritic or other igneous rock, in which the more prominent crystals are embedded.
Origin of groundmass
Examples from the Web for groundmass
Historical Examples of groundmass
Pyroxene, quartz and augite form the groundmass, as seen in section.The Long Labrador Trail
These lavas have groundmass textures that vary from almost holo-crystalline to glassy.
In a basal flow in Moraine Park, the slaggy and compact phases show differences in phenocrysts as well as in groundmass.
- the matrix of igneous rocks, such as porphyry, in which larger crystals (phenocrysts) are embedded