Quartzites are metamorphic rocks that are formed from the transformation of sandstone. They are composed of more than 90% quartz and are known for their durability and strength. Synonyms for the word quartzite include granular quartzite, quartzose sandstone, metamorphosed sandstone, and arenite. Granular quartzite is primarily made up of fine grains of quartz and mica, while quartzose sandstone has a higher concentration of quartz than other minerals. Metamorphosed sandstone is a technical term used to describe the process of transforming sandstone into quartzite. Arenite is a geological term used to describe sandstone that contains more than 90% quartz.