What is the densest material on earth?

Question

Apart from the elements, do we know of materials that are denser (and not including exotic and theoretical matter)? I.e. can an alloy be denser than the sum of its compounds, for example if the new lattice packs denser than each of the compounds it's made from? My curiosity was spurred from rumors of a material called ultradense deuterium (not confirmed to exist), that apparently packs something like 140kg/cm^3.

Answer 1

Densest material on Earth is probably Osmium at 22.59 g/cm³. What the densest material at the Earth's core may be I do not know - probably still Osmium unless some other element forms a higher density allotrope under the pressure.