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How to Calculate the Specific Gravity of a Mineral

Specific gravity is the density of an object relative to the density of water. Specific gravity is considered one of the most important properties of a mineral because it is a constant and quantifiable property, which can be used for comparison. Specific gravity can be invaluable when identifying a mineral.

Things You'll Need

String
Measuring tape with centimeter marks
Scissors
Mineral sample
Triple balance beam
Beaker of water

Instructions

- 1
  Use the measuring tape to measure a piece of string 50 cm long, and cut it to that length with the scissors.
- 2
  Tape the string to the balance plate of a zeroed balance beam, allowing it to hang off the table freely.
- 3
  Measure the mass of the mineral sample in air by placing it on the balance plate and recording its weight.
- 4
  Measure the mass of the mineral sample in water by tying it to the end of the piece of string and letting it hang freely off the table into a beaker of water. Record the weight shown on the scale.
- 5
  Calculate specific gravity. Make the calculation by subtracting the mass of the mineral in water from the mass of the mineral in air (the second result from the first), and then divide the mass of the mineral in air by that result. In other words, divide the mass in air by the mass in air minus the mass in water.
- 6
  To get a more accurate result, repeat the experiment 3 times or more and average them for a final result.

Rocks & Minerals