What type of rock is typically associated with the formation of sapphires?

Sapphires are typically formed in metamorphic rocks. This is due to the high pressures and temperatures involved in metamorphic processes, which create the ideal conditions for the formation of corundum, the mineral that includes sapphires. During metamorphism, aluminum-rich minerals crystallize and can develop into sapphires.

While igneous rocks can also contain corundum, it is within the metamorphic environment that sapphires grow in a stable manner, often forming within parent rocks that were subjected to significant geological changes. The other types of rocks listed, such as sedimentary and volcanic, do not provide the necessary conditions for the high-quality development of sapphires. In summary, the high-pressure, high-temperature environments of metamorphic rocks facilitate the crystal growth of sapphires, making this option the most accurate in relation to their formation.