Quartzite (metaquartzite) is a quartzose, crystalline-textured, metamorphic rock. It forms by intermediate- to high-grade metamorphism of quartzose sandstones and siltstones.
Nacarado Quartzite - faulted impure quartzite from the Precambrian of Brazil.
Stratigraphy & Age: possibly (?) from the S‹o Joaquim Formation, Martin—pole Group, Neoproterozoic, >775 Ma.
Locality: Nacarado Quarry, hills outside of town of Massapˇ, northern Cear‡ State, northeastern Brazil.
Renoir Blue Quartzite - faulted, horizontally-bedded quartzite.
Green Harlequin Quartzite - fuchsitic quartzite (gray = quartz; green = fuchsite, a chromian muscovite mica). This quartzite shows hints of foliation, due to the presence of small sheets of fuchsite mica.