Density and Specific Gravity Quiz

Density and Specific Gravity

• Density measures the mass per unit volume of a material
• A brick sinks in water because its density is higher than that of water, whereas a liter of water floats because its density is equal to that of water

Specific Gravity

• Specific gravity is a ratio of the density of a substance to the density of water
• Different minerals have varying densities, which are reflected in their specific gravities

Measuring Density

• The first step in determining the density of an unknown specimen is to measure its mass
• It's necessary to determine how much water the sample displaces to calculate its volume
• A mineral suitable for measuring density should displace a measurable amount of water when submerged

Calculating Density and Specific Gravity

• Density is calculated by dividing the mass of the sample by its volume
• The volume of the sample is typically measured in cubic centimeters (cc)
• Specific gravity is the ratio of the density of the sample to the density of water
• The specific gravity range for most common rock-forming minerals is approximately 2.5-3.5
• Galena has a specific gravity of about 2.65
• The high density of galena is the property that determines its identity
• The mass of an equal volume of water can be calculated by multiplying the volume of water displaced by the density of water (1 g/cc)