The metric system about mass.?

Other countrys do not use weight like the united states. They use the metric system mass. Is mass how much space can it take up? For an example a quarter have the same mass of a piece of meteorite but it weighs about a ton. Do they use a different form of weight or just the metric system? Weight changes in space, but mass don't. Some people might confuse this with volume also because of how long is in a hollow brick plus sometimes density.