Final answer:
Gneiss is a metamorphic rock that is formed from granite under heat and pressure. It is characterized by alternating bands or stripes of light and dark minerals. Gneiss is different from granite, which is an intrusive igneous rock.
Step-by-step explanation:
Gneiss is a metamorphic rock that is formed from granite under heat and pressure. Metamorphic rocks are rocks that have been subjected to intense temperature and pressure, causing them to undergo a change in form and mineral composition. Gneiss is characterized by alternating bands or stripes of light and dark minerals, which are a result of the intense metamorphic process. It is different from granite, which is an intrusive igneous rock formed from cooled magma.