Glassy Texture

Glassy Texture

 

the texture of volcanic rock that consists entirely of volcanic glass or that contains, in addition to volcanic glass, a small number of crystals (phenocrysts) in the groundmass. Glassy texture is most commonly found in rocks that are rich in silica and poor in calcium, magnesium, and iron. The rapid cooling of lava on the earth’s surface is conducive to the formation of this type of texture.

References in periodicals archive ?
Because even if it is coloured or transparent, when a thin surface is glazed, the glaze becomes a different layer covering the original glassy texture.
Along the sides of the flows, the lava has a glassy texture and breaks into telltale hexagonal columns--twin indications that the flows cooled rapidly.