Final answer:
Minerals form from magma by slowly cooling deep beneath the Earth's surface, allowing large crystals to grow. Different minerals crystallize at different temperatures, with minerals like feldspar forming early with well-defined crystals, and quartz filling the remaining spaces. The resulting rocks, such as granite, are intrusive and have a coarse-grained texture.
Step-by-step explanation:
Minerals are formed by crystallization from magma through a process that includes several key steps. When magma is molten, it intrudes into other rocks deep below the Earth's surface. As the magma starts to cool gradually and slowly, individual crystals begin to form. This slow cooling process is critical because it provides time and space for crystals to grow large, producing a coarse-grained texture.
During the cooling phase, different minerals crystallize at different temperatures. For instance, feldspar, which crystallizes at higher temperatures early in the process, tends to form large, well-defined crystals with straight sides. As the cooling continues, any remaining spaces are often filled with quartz, a clear and glassy mineral that crystallizes later.
The resulting rock depends on the minerals present and the rate of cooling. Intrusive igneous rocks, like granite, are formed when magma cools slowly below the Earth's surface, resulting in visible, interlocking crystals. On the other hand, extrusive igneous rocks form when magma erupts onto the Earth's surface and cools rapidly, leading to a fine-grained texture.