GeoMiner Free earth-science tools

Built by a geologist

Rock & Mineral Specific Gravity Calculator

Specific gravity compares a material's density with the density of water and has no unit. For hydrostatic weighing, first weigh a known-safe, dry specimen in air. Then suspend it completely in clean water without touching the container and record its apparent submerged weight. Calculate specific gravity by dividing the weight in air by the difference between the air weight and the submerged weight. A second method divides dry mass in grams by the volume of water displaced in millilitres; this gives approximate density in grams per cubic centimetre and a similar numerical specific gravity near room temperature. Repeat measurements because trapped bubbles, water absorption, a string or basket, vessel contact, coarse volume markings, mixed grains, pores, coatings, and inclusions can shift the result. Do not immerse valuable, mounted, porous, absorbent, soluble, friable, reactive, contaminated, fibrous, radioactive, or potentially toxic material. Use dedicated equipment and appropriate disposal rather than foodware or a household sink. GeoMiner's calculator keeps all measurements and the result in the browser tab and records only a bounded calculator action. Treat the result as one identification clue alongside hardness, streak, lustre, cleavage, habit, texture, and geologic context—not as an assay, appraisal, or laboratory determination.

Verification resources

Cross-check terminology, classification, methods, and safety with these authoritative external resources.

  • The Hydrostatic Method of Determining Specific Gravity — Gemological Institute of America. Explains Archimedes' principle, hydrostatic weighing, and the air-weight divided by apparent weight-loss formula.
  • Analysis of Gemstones at GIA Laboratories — Gemological Institute of America. Describes current laboratory use of air and suspended-water measurements as one part of gemstone analysis.
  • Natural Gemstones — Mineral Gemstones — U.S. Geological Survey. Defines specific gravity as density relative to an equal volume of water and treats it as a major gemstone property.
  • Water Density — U.S. Geological Survey Water Science School. Explains density, relative density, and why water temperature and dissolved material affect precise measurements.
  • Specific Gravity — Queensborough Community College, City University of New York. Provides a mineral-identification procedure using dry weight and a specimen suspended in water.

Read GeoMiner's editorial methodology.

Common questions

What is mineral specific gravity?
Specific gravity is the ratio of a material's density to the density of water. It is dimensionless. Near ordinary room temperature, its numerical value is close to density expressed in grams per cubic centimetre, but the two terms are not identical.
How do I calculate specific gravity from weights in air and water?
Divide the dry weight in air by the difference between the air weight and the apparent weight while the specimen is fully suspended in water. Keep the same unit for both measurements.
Can specific gravity identify a mineral by itself?
No. It can separate some look-alikes, but mixed grains, inclusions, coatings, pores, trapped bubbles, and measurement error can shift the result. Combine it with hardness, streak, lustre, cleavage, habit, and geologic context.
Should every specimen be immersed in water?
No. Do not immerse valuable, mounted, porous, absorbent, soluble, friable, reactive, contaminated, fibrous, radioactive, or potentially toxic material. Use a qualified laboratory or a non-destructive alternative when damage or exposure is possible.

JavaScript is loading the interactive GeoMiner experience. The identification tools provide educational candidates, not laboratory confirmation.