Question

this is a piece of quartzite. quartzite forms when sandstone is changed by high temperature and pressure. quartzite is made mostly of the mineral quartz. it can also contain small amounts of other minerals. depending on the minerals it contains, a piece of quartzite can be white, gray, pink, red, green, or blue. what type of rock is quartzite? sedimentary igneous metamorphic

Explanation:

文中提到石英岩是砂岩在高温高压下发生变化形成的，符合变质岩的形成特征。变质岩是原有的岩石在高温、高压等条件下发生变质作用形成的岩石。

Answer:

C. metamorphic