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Related to groundmass: mafic, Phaneritic, vesicular


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


(Geological Science) the matrix of igneous rocks, such as porphyry, in which larger crystals (phenocrysts) are embedded



the crystalline, granular, or glassy base or matrix of a porphyritic or other igneous rock, in which the more prominent crystals are embedded.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.groundmass - (geology) the matrix of fine-grained crystalline material in which larger crystals are embedded
geology - a science that deals with the history of the earth as recorded in rocks
igneous rock - rock formed by the solidification of molten magma
porphyritic rock, porphyry - any igneous rock with crystals embedded in a finer groundmass of minerals
References in periodicals archive ?
The pillow lavas have microvesicles that are filled with chlorite; carbonate and opaque minerals that located in a groundmass of plagioclase and clinopyroxene microlites.
Hydraulic conductivity of saprolite as determined by channels and porous groundmass.
The lowermost part of the unit in Slide 9 consists of a compacted calcareous groundmass with a low percentage of embedded charred plant inclusions, and a greater proportion of plant voids (Figure 4D and E).
It consists of ophiolite grains which made up of fine sand-sized, well sorted, subangular to subrounded ophiolite, quartz, chert and micrite limestone grains scattered in groundmass composed of partially dolomitized calcite or micritic matrix.
This is highly encouraging as NEV027 only just intersected the top of the intrusive complex with several large Chim Formation clasts (fragments) incorporated within the porphyry groundmass (as xenoliths).
80]) and clinopyroxene phenocysts in a fine-grained groundmass enclosing interstitial glass.
1985) 1 <30 Manic, only fabric units of one size group or <10 amorphorous material present Cefiiric, coarser units linked by finer material 2 30-50 Chitonie, coarser units are surrounded by a cover of 10-20 smaller units <30 3 >50 Chitonic 20-30 Enaulie, a skeleton of larger units with aggregates <30 of smaller units in the interstitial spaces 4 50-100 30-60 30-60 5 100 Enaulic >60 Porphyritic, larger units occur in a dense <30 groundmass of smaller units Table 2.
They have porphyritic texture with plagioclase phenocrystals (up to 10 %) in a subophitic to intersertal groundmass.
In addition to these visual observations, a powder x-ray diffraction analysis was run on one coprolite specimen to determine the major composition of its groundmass.
4 cm to 1 cm diameter, randomly oriented, subhedral to euhedral, white plagioclase feldspar crystals supported within a quartz and quartzo-feldspathic groundmass that also contains randomly oriented biotite clots and numerous patches of U-staining.