Measuring your Rock Density

Here’s a trick: if you have a sample of your rock type sitting on your desk, and you want to determine its density in units that you can use in the program, follow these instructions. (Note that the numbers shown in italics in our example would be substituted by your own measurements.)

• Measure the rock in all three dimensions using inches (or centimeters). Multiply the three linear dimensions (length x width x height) to determine volume in cubic inches (or cm.).

4.25 x 4.3125 x 5 = 91.64 cubic inches.

• Weigh the rock sample in pounds (or grams). Our sample, above, weighed 6.1 pounds.
• Divide the weight by the volume units to determine pounds per cubic inch (or grams per cubic cm.).

6.1 pounds / 91.64 cubic inches =
0.066565 pounds / cubic inch

• Translate the cubic inches to cubic feet with this multiplier:

0.066565 pounds / cubic inch x 1728 cubic inches / cubic foot =
115.02 pounds / cubic foot

(Or, if you are working in metric units, translate grams per cubic centimeter to grams per cubic meters 
with the multiplier of 1,000,000 cubic cm. / cubic meter.)

• Then, translate the pounds to tons with:

115.02 pounds / cubic foot X 1 ton / 2000 pounds =
0.05751 tons / cubic foot

RockWare home page