How to Calculate the Specific Gravity of Minerals

Specific gravity is the measure of the density of a mineral. Sometimes it's used as a way of measuring minerals because it's the only way to distinguish some minerals without more advanced laboratory techniques. There are no units involved with specific gravity because it is derived from the density of the mineral divided by the density of water (density = mass / volume). As a result, the units of density cancel out. Specific gravity is usually measured by laboratory equipment.

Things You'll Need

• Mass balance
• Minerals being measured
• 50 ml beaker

Instructions

Specific Gravity

1. Weigh the mineral--while dry--on a balance. Then immerse it in water. Weigh the mineral again immersed in the water. Density is mass divided by volume.

2. Use the formula SG = D/D(H20). SG = specific gravity, D = the density of the mineral, and D(H20) = the density of water. If water is used, L = 1, so that the formula is simply D/(D-W). The mineral being tested must be homogeneous and must not contain other minerals.

3. Solve the equation for SG, and you will have the specific gravity.

References

• Gemstones of the World; Walter Schumann; 2007
• Engineering Tool-Box