Igneous rocks are primarily characterized by their texture and composition.

• A. True
• B. False
• C. Only texture
• D. Only composition

Answer: (A)

Igneous rocks are classified by both texture and mineral composition. Texture reveals how quickly the rock cooled and crystallized, which controls grain size and arrangement—for example, coarse grains in granite from slow underground cooling, fine grains in rhyolite from faster surface cooling, or a glassy feel in obsidian from very rapid quenching. Composition shows the chemical makeup of the minerals present, ranging from light, silica-rich minerals in felsic rocks to dark, magnesium-iron-rich minerals in mafic rocks. The combination of texture (cooling history) and composition (mineral content) provides the most complete and practical way to categorize igneous rocks. So the statement is true.