What is the tranchyte in geology ?

Trachyte : definition

Streckeisen diagrams (or QAPF diagrams) - Classification of plutonic and volcanic rocks
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.