The groundmass comprises 80-85 % plagioclase feldspar, with lesser quartz, biotite and magnetite.
12.
In many trachytes, however, the phenocrysts are few and small, and the groundmass comparatively coarse.
13.
Aphanites are commonly porphyritic, having large crystals embedded in the fine groundmass or inclusions are called phenocrysts.
14.
Andesine-labradorite plagioclase and pyroxene phenocrysts are found in the lavas, which has a fine grained groundmass.
15.
Groundmass of rock is the fine-grained mass of material in which larger grains or crystals are embedded.
16.
Phenocrysts below this level, but still larger than the groundmass crystals, are termed " microphenocrysts ".
17.
It can be found in high-grade metamorphic rocks, xenoliths and in the groundmass of rhyolite and dacite.
18.
The NAKP volcanics, including the ML pipes, contain abundant lapilli and olivine supported in a fine-grained groundmass.
19.
The centre of a lava flow is commonly massive and crystalline, flow banded or layered, with microscopic groundmass crystals.
20.
Acting Detective Inspector Alan Fitzgerald said both Virgin Atlantic and the Initial Aviation Security group had supported the investigation, codenamed Operation Groundmass.
