Why is the Density of gold higher than Pyrite?

Answer 1

A couple of reasons... Gold atoms are heavier than either the iron or sulfur atoms that make up pyrite. Also when the iron and sulfur atoms bond in pyrite they form a lattice or patterned arrangement. This leaves room for lots or air in between the atoms. Gold bonds to other gold atoms in a very close arrangement, as close as possible, leaving little space for air.