Minerals share the common physical traits of color, streak, density, hardness, luster, cleavage, fracture, tenacity and crystal habit. These properties vary widely among minerals and, in fact, serve as primary tools for giving minerals their unique individual qualities. However, this group of characteristics enables minerals to be classified as such.
Color is one of the most important distinguishing characteristics of minerals. Minerals vary widely in color: some are translucent and appear as white or light gray, even pastel, while others are darker and reflect light. Streak refers to the color that a mineral takes on when ground into a powder. Along with hardness, it is an important characteristic. Depending on where the mineral falls on the streak scale (like the fineness or softness of its physical appearance when in powder form), mineral powder may be used for cosmetic products and in industrial settings. Cleavage and fracture indicate how easy it is for minerals to break, while crystal habit defines their numbers of crystals.