Cassiterite is a mineral that contains tin oxide. We usually call it tin and it is the greatest source of tin today. It is generally opaque, but its luster and multiple crystal faces cause a nice sparkle.

Before the discovery of iron, tin was added to copper and zinc to make bronze which was used for making tools and weapons.

A little known fact is that tin is difficult to recycle because it is used as a very thin coating on iron and steel to prevent rusting.