Learning Experience 2: Mineral Identification

TEACHER’S GUIDE

Materials:

For each group of three students:

3 Student Activity Sheets for Learning Experience 2 (Please see PDF)

Set of rock and mineral samples

Rock Samples

1. Shale

2. Granite

3. Pink Sandstone

4. White Marble

5. Pumice

6. Obsidian

7. Limestone

8. Slate

9. Fossil Sandstone

10. Anthracite

Mineral Samples

11. Graphite

12. Galena

13. Magnetite

14. Hematite

15. Talc

16. Gypsum

17. Biotite

18. Calcite

19. Pink Felspar

20. Quartz

21. Garnet

Eyewitness Rocks & Minerals Book

Golden Guide Rocks & Minerals Book

Earth's Restless Surface Book

Metal tweezers

Streak plate

Steel nail

Bar magnet

#82 rubberband

2 fahnestock clips

#48 bulb

Bulb holder

3 10 cm pieces of copper wire

Double lens magnifier

Dropper bottle of hydrochloric acid

3 pairs of safety goggles

“D” cell battery

Penny

Paper towels

Preparation:

Study the Eyewitness Rocks & Minerals Book, Golden Guide Rocks and Minerals, and Earth's Restless Surface book before starting the Learning Experience. Read the background information in the Rocks, Minerals, and Landforms Teacher’s Manual. (Please see PDF)

Discuss safety concerns prior to completing the hydrochloric acid test. Please have students wear rubber gloves when using hydrochloric acid. If hydrochloric acid is exposed to skin or eyes, please wash out immediately with water. Eye safety is essential when working with hydrochloric acid. Safety goggles are required, therefore, students should be assigned a pair of goggles to be use throughout the unit. Goggles should not be shared by students due to sanitary reasons.

Basic Skills Development:

Gathering and Organizing Data

Interpreting Data

Observing

Classifying

Discussing

Describing

Evaluation Strategy:

Students will complete various tests on their mineral collection and will identify the properties of various minerals.

Vocabulary:

mineral

attraction

luster

magnet

streak

magnetism

cleavage

electricity

circuit

plane

fracture

resistance

hardness

acid

reaction

Objective: Students will observe and identify mineral samples through testing of samples.

What are the properties of various minerals?

Students are to complete a variety of tests on the various minerals that help with mineral identification and the identification of the properties of these various minerals. The activity sheet for Learning Experience #2 in the Rocks and Minerals and Landforms Student Activity Book (Please see PDF) provides a chart for students to record the results of their various tests. The minerals on the chart may be described by their luster. The minerals are either metallic in their luster, nonmetallic, or both.

Session 1

Remove only one sample at a time. Replace the sample in the correct location after each observation. Using the double lens magnifier, have groups of students focus on one sample of each mineral and discuss their observations.

Discussion Questions:

What things do you observe that makes each mineral different?

What things do you observe that makes each mineral similar?

Session 2

Color and Streak

Observe the color for each mineral in your collection and record the color for each mineral on your activity sheet for Learning Experience #2 in the Rocks and Minerals and Landforms Student Activity Book. (Please see PDF) Explain to students that each mineral sample also leaves a distinctive streak.

Students are to create a mark on their streak plates with each mineral and record the color of that streak on their activity sheet for Learning Experience #2 in the Rocks and Minerals and Landforms Student Activity Book. (Please see PDF) Tell students that the color of the mineral sample may vary, but the color of the streak of that mineral is nearly the same.

Discussion Questions:

How do the minerals’ colors and streaks compare?

What things do you observe that makes each mineral different?

What things do you observe that makes each mineral similar?

Session 3

Hardness and Cleavage or Fracture

Hardness is the resistance of a rock surface to scratching. Minerals can be ranked by hardness. The Mohs’ scale of hardness is as follows: If a mineral can be scratched by a fingernail, like talc, it has a hardness of

or 2. If it can be scratched by a penny, its hardness is 3 or 4. If a steel

nail can scratch it, its hardness is 5 or 6. If a diamond can scratch it, its hardness is 7, 8, or 9. A diamond has a hardness of 10. Students are to use the mineral sample and the penny and steel nail, to find where the minerals fall on the Mohs’ scale of hardness. Students will record the results on the chart on their activity sheets for Learning Experience 2 in the Rocks and Minerals and Landforms Student Activity Book. (Please see PDF)

Discussion Questions:

How does the hardness of the minerals compare?

What things do you observe that makes each mineral different?

What things do you observe that makes each mineral similar?

Session 4

Cleavage is one way minerals split along planes. If a mineral has cleavage, the mineral splits along a flat surface. Biotite has perfect cleavage along one plane. Calcite has perfect cleavage along three planes. If the mineral does not break apart along a flat surface, it is known to fracture.

Students are to examine the minerals in their collection to observe if the mineral has cleavage or if it fractures. Students are to then record that information on the chart on their activity sheet. They are to put an “X” in the correct box (cleavage or fracture) to indicate their findings.

Session 5

Hydrochloric Acid Test

Safety Notice:

All students in the classroom should wear safety goggles when using hydrochloric acid. Do not allow hydrochloric acid to remain on the skin for any period of time. It is imperative that a supply of paper towels and water be available to rinse and dry hydrochloric acid on the skin.

Water should be used to flush acid from the eyes. Soap or detergent is all that is necessary to neutralize small amount of dilute hydrochloric acid. The rock samples and the students’ hands should be washed after all testing is complete.

Some minerals are a base, or contain a base. When a drop of hydrochloric acid is placed on a mineral that contains a base or is a base, the acid will react by bubbling or foaming.

Place the mineral sample to be tested on a paper towel. Students are to place one drop of hydrochloric acid on each mineral sample and observe. Students are to record their observations on the chart on their activity sheet for Learning Experience #2 in the Rocks and Minerals and Landforms Student Activity Book. (Please see PDF)

Discussion Questions:

What mineral samples reacted with the hydrochloric acid and which samples did not?

Session 6

Magnetism and Electricity

Some of the mineral samples are attracted to a magnet and the strength of the attraction depends on the quantity and quality of iron in the mineral samples. Magnetite and hematite will be attracted to a magnet. Use a magnet to test each mineral sample to see if a magnet is attracted to it. Record results on the chart on the activity sheet for Learning Experience 2 in the Rocks and Minerals and Landforms Student Activity Book. (Please see PDF)

Once students test to see if the minerals provided are attracted by a magnet, they are to then test to see if the minerals provided conduct electricity. Students are to set up a test circuit with their batteries, #48 bulbs, and three wires. They are to place the end wires on the rock sample and observe to see if the bulb lights. If it does, then the sample is a conductor of electricity. Galena (lead ore) and sometimes magnetite and hematite will conduct electricity. The greater the quantity of iron in magnetite and hematite, the better conductor of electricity the rock sample will be. Students should complete their chart on their activity sheet and compare their results.

Discussion Questions:

Were their any mineral samples that were attracted to the magnet?

Did any mineral samples conduct electricity?

Did any mineral samples respond to the magnet and conduct electricity?

To see the Properties of Common Minerals, check out page 27 of the Teacher’s Manual. (Please see PDF)

For the accompanying Rocks, Minerals, and Landforms Student Activity Book, please refer to the PDF found here. (Please see PDF)

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