Trachytic Texture

Trachytic Texture

 

a texture of extrusive rocks in which the groundmass contains little volcanic glass and consists predominantly of minute tabular crystals, namely, sanidine microlites. The microlites are parallel, forming flow lines along the directions of lava flow and around inclusions. Trachytic texture occurs in rocks that are rich in alkalies; hence the vitreous mass of the rocks has a relatively low viscosity. Trachytic texture is especially characteristic of trachytes and rocks similar to trachytes. (See alsoTEXTURE AND STRUCTURE OF ROCKS. ) [26–513—4]

References in periodicals archive ?
Hornblende-feldspar porphyries, displaying flow or trachytic textures, occur as the extrusive equivalent of the intrusive dikes.