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How to Use Specific Gravity

You can use specific gravity to get a measurement of how dense a mineral is. You can use the specific gravity formula and apply it at home without the need for expensive laboratory equipment. The meaning of the specific gravity formula is that you are comparing the density of water to the density of the unknown mineral that you are weighing. Once you have the difference you can use your answer to interpret what type of mineral you have.

Things You'll Need

Scale
Beaker
Water
String

Instructions

- 1
  You will need to make sure you use the same type of weight scale throughout the experiment. You can weigh everything in grams, pennyweight, pounds, or tons; it will not matter for the following formula as long as you stay consistent.
- 2
  Make sure you have the pure mineral. If you have a rock that is mixed, break off the mineral that is of interest to you. Take this mineral and weigh it dry on the scale.
- 3
  Grab your beaker and partially fill it with water. Suspend the mineral you have just weighed with a string so it sits freely in the beaker of water but make sure the mineral is fully submerged in the water without touching the bottom of the beaker. Take your weight measurement.
- 4
  You will use the following formula to obtain the Specific Gravity of your mineral.
  
  SG: Specific Gravity
  D: Dry Weight of Mineral
  W: Wet Weight of Mineral
  
  SG = D/ (D-W)
  
  You can use your answer and match it up with the chart below (see resources) to find out what type of mineral you have.

Rocks & Minerals