The answer is letter D. Geologists identify minerals by color, streak and fracture. They look closely at physical properties of minerals and identify and classify them accordingly. Basic properties of rocks are color; hardness, determined through scratch marks applied to softer materials; luster, describes how shiny a mineral is on the surface; streak, refers to the color of minerals when powdered; cleavage and fracture, both refers to the surface of the mineral, its breaks, smoothness, roughness, and jagged edges; and chemical properties, chemical reactions that occur in minerals when mixed with other components.