Igneous rocks observed in thin sections can be classified into three types of volcanic facies (Figure 4): effusive, intrusive, and extrusive rock. Effusive facies represents magma that has erupted ...

Rocks are categorized into three main types: igneous, sedimentary, and metamorphic. There are over 4,000 identified minerals on Earth. Common rocks include granite, basalt, limestone, and sandstone.

An igneous rock has come to be regarded, more constantly than before, not merely as a mineral-aggregate, but as-the product of consolidation of a molten rock-magma; and consideration has been ...