Ovoidal- and mottled-textured rock and associated silica veinlets and their formation by high-temperature outgassing of subjacent magma

Ovoidal (or gusano) texture is characterized by ovoids of hydrous aluminum silicate/
sulfate minerals such as pyrophyllite and alunite associated with variable
amounts of pyrite and enargite or covellite set in a typically fine-grained matrix of
quartz or chalcedony. Inmottled (or patchy) texture the aluminum silicate/sulfate and
silica portions are irregularly intermixed. There is a continuum between ovoidal and
mottled textures.