Gneisses tend to be named based mostly on their own protoliths, and petrologists use the overall terms orthogneiss ), and during metamorphism any initial sedimentary textures ended up erased. Typical quartzites are white or grey, but minor parts could add shade. The pink colour During this sample comes from hematite https://www.generationgenius.com/videolessons/rocks-and-minerals-video-for-kids/