Glass has a density of 2.5 g/cc and is the most commonly used bead media for "beadbeating." Beads are sold in one pound bottles with easy pour spouts.
Zirconia beads have a density of 5.5g/cc (Twice as dense as glass beads - good for tough tissue). Sold in one pound bottles.
Listed bead sizes are median (average) values. Because beads are sorted by sieves, bead size varies between +/-10% of a listed value.