Specific gravity is one of the most important, constant, and measurable properties of minerals. It is the density of the mineral relative to water. For example, quartz has a specific gravity of 2.6, meaning that the mass of quartz is 2.6 times greater than the mass of the same volume of water. Minerals with a specific gravity greater than 2.8 are called heavy minerals, and among them are many ore minerals, e.g., magnetite, chromite, ilmenite, garnet, zircon, as well as valuable native elements like diamond, gold, and platinum.

Fracture is the texture and shape of the surface of a mineral that results when the mineral breaks. It differs from cleavage, which is the regular breaking along planes where the cohesion in the mineral structure is weaker, in that it refers to irregular, general breakage. Every mineral has a recognizable, characteristic fracture, which can be used in mineral identification. Fractures can be conchoidal, hackly, splintery, uneven, or earthy. All minerals have fractures, however, in minerals with strongly developed cleavage, like micas, fractures are very difficult to observe.

Streak is the powdery trace left by a mineral when scraped along a rough ceramic surface, and it corresponds to the true colour of the mineral. Every mineral has a unique streak, which may not necessarily match its visible color. For example, calcite can appear in many different colours, but it has a white streak. In mineralogy, the colour of a mineral is one of the primary diagnostic properties, and mineralogists determine the streak of a mineral to identify its true colour. Determining the streak is particularly useful for distinguishing between two minerals of the same colour but different streaks, such as gold (yellow) and pyrite (brownish-black or greenish-black).