👉 Tephrite, a type of sedimentary rock, is composed primarily of silicate minerals such as quartz and feldspar, with some calcium carbonate present. It forms in areas where there is a high concentration of water, often found in the rocks below sea level or on the surface of bodies of water like lakes and rivers. The term "tephrite" refers to its distinctive appearance, which includes irregularities and streaks due to the presence of mineral grains or fractures within the rock.
