Question

what effect does a fast cooling rate have on grain size in igneous rocks? it forms light crystals. it forms fine - grained crystals. it forms large - grained crystals. it forms dark crystals.

Explanation:

When magma or lava cools quickly, there is less time for mineral crystals to grow. In igneous rocks, a fast cooling rate means that the crystals do not have enough time to develop into large - sized grains. Fine - grained crystals form because the rapid cooling stops the growth of crystals at an early stage. Light or dark crystals are related to the mineral composition (e.g., felsic or mafic minerals) rather than the cooling rate. Large - grained crystals form when there is a slow cooling rate, allowing more time for crystal growth.

Answer:

It forms fine - grained crystals.