The color of a rock is primarily determined by mineral type. Different minerals have distinct colors and can significantly influence the overall appearance of the rock. Additionally, the presence of certain elements or compounds, as well as the rock's history (such as weathering and alteration processes), can also affect its color.
While texture, grain pattern, and grain shape can influence how a rock looks, they mainly affect visual characteristics like luster, roughness, and the way light interacts with the rock surface rather than its inherent color, which is predominantly a result of the minerals present.