SANDS
Created by Dr. Ronald Takata
Hawai'i Space Grant Consortium Associate Director, Honolulu Community College,
Future Flight Hawai'i instructor.

1. To study different types of sand.
2. To perform chemical tests to identify the type of sand.

Coral sand, desert (silica) sand, black lava sand, limestone, marble, chalk, glass beads, lemon juice, vinegar.

Procedure

1. Place several grains or a small piece of each type of sample on a labtop.
2. Add 3 drops vinegar to each.
3. Observe and record your results.
4. Run the end of a bar magnet through sand samples.
5. Observe sand samples with a magnifying glass.

Rinse the labtop into a waste container with a stream of water. Filter the particles out using a piece of filter paper in a funnel. The filtrate may be poured down the drain.

Questions

1. Identify the chemical composition of each type of sand or sample.

   * Red ocean sand contains high iron content which oxidizes to iron oxide, which is red. Black lava sand is black due to the presence of manganese compounds, which are black. White coral/ocean sand comes from coral, seashells, calcarious algae, which produce structures made of calcium carbonate, a white compound. Desert (quartz) sand is colorless or pastel transparent/translucent solid, which appears white as its surface is abraded.

2. What is the name and formula of the gas produced by some samples?

   * Carbon dioxide, CO₂

3. What is the chemical component common to the samples which give off gas.

   * The coral/ocean sand produces bubbles with vinegar because coral/ocean sand is composed of calcium carbonate, which decomposes, releasing carbon dioxide upon contact with any acid. Lava sand and desert (quartz) sand, which are primarily silicates, are stable in acid.

4. Why is marble found in Colorado and limestone found in Arizona?

   * Colorado and Arizona, as well as most of the middle section of North America, was once covered by an ocean that stretched from the Arctic Ocean to the Caribbean Sea. Coraline sand was deposited at the bottom of this body of water, and produced sandstone deposits. Over geologic time the land mass rose and the ocean receded producing the current North American continent. Due to time, heat, and pressure, the sandstone was transformed into limestone, then into marble. The marble deposits in the Rocky Mountains and the omnipresent limestone deposits (Grand Canyon, Bryce Canyon), all composed of calcium carbonate, were once marine shells and corals. Incidentally this oceanic history of this region explains why petroleum deposits, the product of marine life deposits, have been found there.

5. Which of the sand samples is biogenic (made by living organisms)?>p>

   * The white sand from Hawaii's beaches originated from marine shells and corals.

6. Which sand samples are terragenic (made by geological processes)?

   * The black and green sands came from lava and are terragenic. The beige, silica sand is from geologically formed igneous rocks.

7. What is the likely chemical identity of the sand grains which are attracted to the magnet?

   * Black sand particles which are attracted to the magnet are magnetite, an iron oxide, which has magnetic properties.

Extensions

1. Sand sample from card sandglyph.
   a. Examine the sandglyphs with a magnifying lens for evidence of terragenic or biogenic origin.
   b. Scrape a few grains of each type of sand onto a plastic sheet. Add two drops of vinegar to each sand sample.
   c. Observe. Explain the results.

2. For teachers with access to larger samples of sand.
   a. Obtain coral reef sand, black lava sand, desert sand, river sand, and other sand samples.
   b. Place a few grains of each type of sand on a plastic sheet. Alternatively, place 1/4 teaspoon of sand samples into separate small plastic cups.
   c. Study each sand sample with a hand lens.
   d. Pass a magnet over each sample of sand.
   e. Add a few drops of vinegar to each sand sample.
   f. Observe. Explain your results.