PROCEDURE FOR DETERMINING ROCK WEIGHTS, SIZES …
1. The graph in Figure 3 and formulas are for rock that has a specific gravity of 2.65 (165 pounds per cubic foot). Use this graph or formula unless the actual specific gravity (Gsa) is known and varies more than 5 percent (±0.13) from 2.65. To correct to the actual weight (Wa) use this formula: Wa = (W from Figure 3/2.65) x Gsa. 2.