Density
Density is how much mass is packed into a given volume, and most meteorites are denser than typical Earth rocks.
Two rocks of the same size can feel very different in your hand. That difference is density, the mass of something divided by its volume, usually written in grams per cubic centimetre (g/cm³). Water has a density of 1 g/cm³. Common Earth rocks such as granite and sandstone are around 2.6–2.8 g/cm³.
Meteorites often feel surprisingly heavy because many contain iron-nickel metal. Iron meteorites are about 7.5–8 g/cm³, nearly three times the density of ordinary rocks. Ordinary chondrites, the most common stony meteorites, are usually around 3.2–3.5 g/cm³, and stony-iron meteorites fall in between. Some carbonaceous chondrites, such as Murchison, are lighter, because they contain clay minerals, water and pores.
You can measure density at home with an adult's help. Weigh the rock on kitchen scales, then find its volume by lowering it into a measuring jug of water and noting how much the water level rises: 1 millilitre equals 1 cubic centimetre. Divide mass by volume. A high result is a useful clue, but heavy Earth materials such as hematite, magnetite and slag can score highly too, so density alone cannot prove a meteorite.
Related terms
Level: Explorer Ages 10 and up