How do you determine if a rock is igneous sedimentary or metamorphic?

Answer 1

Speaking in very general terms, and with plenty of exceptions, igneous rock may possess larger visible crystals (granite), may be glassy (obsidian), may have air pockets or bubbles present (pumice), and may be dark green or black-ish (basalt). Sedimentary rock may display sediment layers (like shale), may contain fossils (fossiliferous limestone), and may be fine grained (chemical limestone). Metamorphic rock may display foliation (parallel layers of light and dark minerals)(like gneiss), may have a wavy appearance to the foliation, have platy cleavage, or sparkle from the mineral mica (mica schist).

Answer 2

To determine if a rock is igneous, sedimentary, or metamorphic, you can look at its mineral composition, texture, and any layering or banding present. Igneous rocks typically have interlocking crystals, sedimentary rocks often have visible grains or fragments, and metamorphic rocks may show signs of recrystallization or foliation from intense heat and pressure. Additionally, considering the rock's location and the surrounding geological context can also provide clues to its origin.