What is the term for the ratio of a mineral's weight to the weight of an equal volume of water?

What is the term for the ratio of a mineral's weight to the weight of an equal volume of water?

• A. Specific gravity
• B. Density
• C. Mass
• D. Volume

Answer: (A)

Specific gravity is the ratio of a mineral’s weight to the weight of an equal volume of water. This dimensionless number compares the mineral’s density to that of water (since water has a density of about 1 g/cm^3, SG is effectively the mineral’s density expressed in g/cm^3). It’s a practical way to gauge how heavy a mineral is for its size, which helps identify minerals: quartz ≈ 2.65, galena ≈ 7.5, gold ≈ 19.3. Remember, density is mass per volume, while specific gravity uses a reference (water) to express how dense a mineral is relative to water; volume alone isn’t a ratio, and mass alone isn’t a ratio either.

Specific gravity is the ratio of a mineral’s weight to the weight of an equal volume of water. This dimensionless number compares the mineral’s density to that of water (since water has a density of about 1 g/cm^3, SG is effectively the mineral’s density expressed in g/cm^3). It’s a practical way to gauge how heavy a mineral is for its size, which helps identify minerals: quartz ≈ 2.65, galena ≈ 7.5, gold ≈ 19.3. Remember, density is mass per volume, while specific gravity uses a reference (water) to express how dense a mineral is relative to water; volume alone isn’t a ratio, and mass alone isn’t a ratio either.