The ratio of the mass of a solid or liquid to the mass of an equal volume of distilled water at 4°C (39°F) or of a gas to an equal volume of air or hydrogen under prescribed conditions of temperature and pressure. Also called relative density.
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.
for every elements, there is a unique specific gravity. and as we know pharma cos use many elements to make a particular drug. so the drug also has got a particular unique specific gravity. one can identify if the drug is pure in its form or any impurities are there , just by finding the specific gravity.
Hope this helps.