Primary rocks are types of rocks that form directly from the solidification of molten magma or lava. They are also known as igneous rocks. The characteristics of primary rocks depend on the composition of the magma or lava from which they form, as well as the conditions under which they solidify.
There are two main types of primary rocks: intrusive and extrusive. Intrusive rocks form when magma solidifies below the surface of the earth. Because they cool slowly, they tend to be more coarse-grained and have a more crystalline texture. Examples of intrusive rocks include granite, gabbro, and diorite. Extrusive rocks form when lava solidifies above the surface of the earth. Because they cool quickly, they tend to be finer-grained and have a more glassy texture. Examples of extrusive rocks include basalt, andesite, and pumice.
Primary rocks are an important source of information about the geology of an area, as they provide insight into the composition and temperature of the magma or lava that formed them. They are also an important resource for various industries, including construction and manufacturing.