They are feldspar, muscovite and quartz. Igneous rocks are classified by their texture. This is determined by the rate of cooling. Extrusive rocks such as basalt cool rapidly and are fine-grained. Intrusive igneous rocks cool very slowly and are coarse-grained.
Granite is an example.
Common rock forming minerals are formed at higher temperatures and pressures than in atmospheric conditions. As a result, they are unstable and weather or breakdown when exposed to lower temperatures and pressures. These particles are carried to the coast by rivers in suspension by the river currents. Fronts are often seen where rivers enter the ocean. The Brazos Rivers also forms these fronts.