What is the trachyte in geology ?
Trachyte : definition
Trachyte is a whitish to gray volcanic rock, microlitic and fluidal, rarely porphyritic, often slightly porous. It is composed of sanidine (microlites and phenocrysts), anorthose and albite, accompanied by biotite and amphibole in a sparse vitreous mesostasis.
Varieties are distinguished on the basis of mineralogical peculiarities ; presence of aegirine, phlogopite or plagioclase (oligoclase).
Trachytes are viscous lavas that do not constitute flows but lava domes. It is the volcanic equivalent of syenites.
Varieties are distinguished on the basis of mineralogical peculiarities ; presence of aegirine, phlogopite or plagioclase (oligoclase).
Trachytes are viscous lavas that do not constitute flows but lava domes. It is the volcanic equivalent of syenites.
Trachyte from Puy-de-Dôme
Puy-de-dôme view © Aquila18