The most abundant phenocryst minerals were hornblende and plagioclase, but an unusual phenocryst mineral was also present the calcium sulfate, anhydrite.
12.
The most abundant phenocryst minerals were hornblende and plagioclase, but an unusual phenocryst mineral was also present the calcium sulfate, anhydrite.
13.
High in fiamme, the third tuff layer differs from the second in that it has even higher phenocryst content, but poor lithics.
14.
A "'phenocryst "'is a relatively large and usually conspicuous crystal distinctly larger than the grains of the rock recrystallization.
15.
Normally the term " phenocryst " is not used unless the crystals are directly observable, which is sometimes stated as greater than . 5 millimeter in diameter.
16.
Chemical classifications are preferred to classify volcanic rocks, with phenocryst species used as a prefix, e . g . " olivine-bearing picrite " or " orthoclase-phyric rhyolite ".
17.
Oroscocha is formed by phenocryst-rich, felsic porphyritic rocks with a composition of peraluminous rhyolite in the flows and trachydacite in the dome, of which the dome is darker than the lava flows.
18.
Iddingsite forms from the weathering of basalt in the presence of liquid water and can be described as a phenocryst, i . e . it has megascopically visible crystals in a fine-grained groundmass of a porphyritic rock.
19.
In some cases, felsic volcanic rocks may contain phenocrysts of mafic minerals, usually hornblende, pyroxene or a feldspar mineral, and may need to be named after their phenocryst mineral, such as'hornblende-bearing felsite '.
20.
The above approach of FTIR has successfully detect the occurrence of H 2 O and CO 2 in numbers of studies nowaday, For examples, the water saturated inclusion in olivine phenocryst erupted at Stromboli ( Sicily, Italy ) in consequences of depressurization, and the unexpected of occurrence of molecular CO 2 in melts inclusion in Phlegraean Volcanic District ( Southern Italy ) revealed as the presence of a deep, CO 2-rich, continuous degassing magma.
