Mineral Formation

Minerals

Multiple Choice

Maria gets a kit that lets you grow a mineral. The instructions say to pour a packet of liquid into a small container and to place the container in a sunny area. Maria follows the directions and when the liquid evaporates, she observes tiny minerals that are left behind in the container.

What is this process called?

• oxidation

• crystallization

• altering minerals

• organic mineral formation

​Explanation

• The correct answer is B, crystallization, the process by which atoms are arranged to form a material that has a crystal structure.

• A is not correct, as it was not a chemical reaction with oxygen.

• C is not correct because altering minerals requires extreme changes in heat and pressure.

• D is not an accurate description of the process, since it doesn’t necessarily include organic minerals.

Fill in the Blank

Evan reads that some minerals can come from organic processes. Where does the energy ultimately come from that is needed for organic minerals to be made?

​Explanation

The correct answer is the sun. For example, animals such as cows and humans produce skeletons that contain the mineral calcium phosphate. Cows and humans eat plants that used the energy of the sun to make their food through photosynthesis.

Multiple Choice

Minerals can be differentiated by their properties. Density is one property that can be used to tell different minerals apart. A mineralogist is testing a sample of a mineral that has a mass of 5 g and a volume of 2.5 cm³. Use the chart to determine which type of mineral the sample is.

• Morenosite

• Pitticite

• Grayite

• Trimounsite

​Explanation

The correct answer is A, morenosite. It has a density of 2 g/cm3 , which is calculated by dividing 5 g by 2.5 cm3 , using the formula density = mass/volume.

Multiple Choice

A geologist is comparing the properties of different minerals. He rubs each one on a piece of white tile and observes the color of the powder that is left behind. What type of test did he perform?

• color

• hardness

• luster

• streak

​Explanation

The streak of a mineral is the color of its powder and is a way to identify different minerals.

• Hardness is judged by scratching other minerals.

• Luster is the amount of light that is reflected by the surface of the rock.

Remember that when a rock is rubbed on the ground, it leaves a streak of color behind. This is how a streak test is performed.