Specific gravity measures the ratio of the weight of a mineral to the weight of an equal volume of water. Specific gravity is related to the density of a mineral.

Specific gravity = weight of the mineral ÷ weight of equal volume of water

For example, the specific gravity of pyrite is 5.0. The specific gravity of gold is 19.3. Therefore, pyrite is 5.0 times heavier than water. Gold is 19.3 times heavier than water. A piece of gold feels much heavier than a piece of pyrite the same size.

Magnetism

A few minerals exhibit magnetism. Magnetite (Fe_{3}O_{4}) is the most common magnetic mineral.

Magnetite is a naturally magnetic iron oxide mineral. The mineral is also called lodestone, and was used in compasses. (Photograph by Parvinder Sethi)