Short Answer 
Rocks are categorized into sedimentary, igneous, metamorphic, and primitive, each with unique origins; igneous rocks like granite and basalt differ in cooling rates and textures. Granite is durable and valued in landscapes, while basalt is crucial in forming oceanic crusts, highlighting their geological significance.
Step 1: Understand Rock Categories
Rocks can be divided into four primary categories: sedimentary, igneous, metamorphic, and primitive. Each category has distinct origins and characteristics. Sedimentary rocks are formed from particles and organic materials, while igneous rocks originate from cooled magma. Metamorphic rocks arise from the transformation of existing rocks under heat and pressure, and primitive rocks refer to the earliest forms of rock.
Step 2: Recognize Key Igneous Rocks
Among igneous rocks, granite and basalt are two significant types. Both rocks form from magma but differ in their cooling rates and locations. Granite, often found in continental crust, is slow to cool, resulting in a coarse texture. Conversely, basalt cools rapidly upon reaching the surface, creating a fine texture. Both are rich in silicates but serve different geological roles.
Step 3: Discover Their Significance
The significance of granite and basalt extends to their applications and locations. Granite is widely appreciated for its durability and beauty, and it is prominently featured in landscapes like Mount Rushmore and Yosemite National Park. Basalt plays a key role in forming oceanic crusts due to its extrusive nature. Understanding these rocks enhances one’s appreciation of geological processes and the Earth’s structure.