Limestone (CaCo3)

Student Objectives: Students will be able to identify limestone’s usual color as well as some of its uses, both in its natural form and as a processed mineral.

Tips for the Teachers: Illustrate the role of limestone in cave formations by using resources such as films, filmstrips, books and guest speakers. Bring in items that contain calcium carbonate and discuss their differences.

Suggested Activities:

1. Make eggshell ornament according to the season by making tiny holes at each end of an egg and blowing the contents into a dish. Decorate with paint, markers, sequins, bits of felt, etc.

2. Have students make pictures with colored chalk.

3. Use small seashells to make collages or dioramas. Use large seashells to make dish gardens.

4. Check with artist’s guild or art gallery to see if there are limestone carvings available in your area for viewing. Invite a museum curator or artist to class for demonstration.

Measurements/Evaluation:

1. What is limestone’s usual color?

2. When limestone is crushed and heated, it becomes what?

3. How was limestone used in making the Grand Coulee Dam?

4. Limestone is made mostly of calcium carbonate. What tiny animal part makes calcium carbonate?

5. List five ways that limestone and its products are used.

Limestone

Limestone is a type of rock made of the minerals calcite, a form of calcium carbonate. They are the broken-down shells of millions of tiny animals that lived in the sea a long time ago. Calcium carbonate is found in limestone, marble, chalk, seashells, coral, egg shells and cave formations. It is used in white paint, toothpaste, rubber, cleaning powder and paper.

Limestone is usually gray, but it can be very light or very dark-colored, depending on what other minerals are in it. Many people like the look of limestone, and it is often used as a building stone. Limestone is also important to the building industry in other ways.

When limestone is crushed and heated, it becomes a white powder called lime. The mortar between bricks is made of lime, sand and water. Lime is used for many things, including glassmaking, metallic ore processing and making baseball diamonds.

Limestone is also ground up and burned along with clay or shale to make the mix for cement. Almost 100 million cubic yards are poured every year. Washington State’s Grand Coulee Dam was built with 10,585,000 cubic yards of cement. That would be enough cement to build a two-lane highway from Seattle to New York.