Question

Rank the following materials from least to greatest density: Cast aluminum, cold-drawn steel, limestone, marble, packed gravel, and copper.

Answer

Ranked from least to greatest density:

Packed Gravel: 110 pounds per cubic foot (1762 kilograms per cubic meter)
Limestone: 135 pcf (2162 kg/cu m)
Cast Aluminum: 165 pcf (2643 kg/cu m)
Marble: 173 pcf (2771 kg/cu m)
Cold-Drawn Steel: 490 pcf (7849 kg/cu m)
Copper: 556 pcf (8906 kg/cu m)

Gold, by the way, at 1205 pcf (19,302 kg/cu m), is over twice as dense as steel.