Density and Specific Gravity Quiz

What was the initial volume of the sample before it was placed in the water?

What was the volume of water displaced when the sample was placed in the water?

What is the formula for calculating the density of the sample?

What is the density of the sample?

What is the specific gravity of the sample?

Which property of the sample is characteristic of galena, the common form of lead?

What is the typical specific gravity range for common rock-forming minerals?

Which of the following minerals has a specific gravity greater than 20?

What is the key difference between the weight of a pound of feathers and a pound of bricks?

Why does a liter of bricks weigh more than a liter of water?

What property is used by mineralogists to describe the density of a mineral?

What is the first step a novice mineralogist should take to determine the density of an unknown specimen?

How does the density of a mineral relate to its ability to sink or float in water?

What is the purpose of using a beaker of calibrated water to measure the density of an unknown mineral sample?

Why is the concept of density important for identifying minerals?

To measure the density of a sample, you need to know its mass and volume.
The volume of the sample can be determined by measuring the volume of water it displaces.
In this example, the initial water level was 100 cc, and it rose to 120 cc after adding the sample, so the sample displaced 20 cc of water.

Density is calculated by dividing the mass of the sample by the volume of water displaced.
Density = mass / volume of water displaced.
In this example, density = 150 grams / 20 cc of water = 7.5 grams/cc.

Specific gravity is the ratio of the sample mass to the mass of an equal volume of water.
It is calculated by dividing the mass of the sample by the mass of the same volume of water.
In this example, specific gravity = 150 grams / 20 grams = 7.5.
The units of specific gravity cancel out, making it a unitless value.

Most common rock-forming minerals have a specific gravity between 2 and 3.
Quartz has a specific gravity of 2.65.
Metallic minerals like galena are more than twice as dense, with a specific gravity of 7.5.
Gold has a specific gravity of around 20, and platinum has a specific gravity of about 22.
Graphite and gypsum are less dense minerals with a specific gravity just over 2.

Density and specific gravity are used to differentiate between minerals.
Understanding density and specific gravity is essential for identifying minerals.
They are also important in understanding how different materials will behave in different situations.