Earth's Minerals (Book)

Density describes how much matter is in a certain amount of space. Substances that have more matter packed into a given space have higher densities. The water in a drinking glass has the same density as the water in a bathtub or swimming pool. All substances have characteristic densities, which does not depend on how much of a substance you have.

Mass is a measure of the amount of matter in an object. The amount of space an object takes up is described by its volume. The density of an object depends on its mass and its volume. Density can be calculated using the following equation:

Density=Mass/Volume

Samples that are the same size, but have different densities, will have different masses. Gold has a density of about 19 g/cm³. Pyrite has a density of only about 5 g/cm³. Quartz is even less dense than pyrite, and has a density of 2.7 g/cm³. If you picked up a piece of pyrite and a piece of quartz that were the same size, the pyrite would seem almost twice as heavy as the quartz.