Materials Included In Kit

Prelab Preparation

1. Place approximately 300 g of sand into each geology sample container.
2. Place 10 random rock, mineral or fossil samples into each geology sample container.
3. Mix the sand and the rock, mineral, and fossil samples in the geology sample container.
4. Make a copy of each of the sorting sheets and the Specimen Identification Key for each student group

Safety Precautions

Follow all normal classroom guidelines. Remind students to wash their hands thoroughly with soap and water before leaving the laboratory.

Disposal

All materials should be saved for future use.

Teacher Tips

• Enough materials are provided in this kit for six groups of students or 30 students working in groups of five. This laboratory activity can reasonably be completed in one 50-minute class period. List any special equipment or alternative chemicals or equipment.
• There are enough weighing dishes and magnifying glasses supplied for two of each for each group.
• If time allows, have all student groups work together at the end of the activity to create a complete set of sort sheets using all of the specimens.
• The rock and mineral samples may be further divided and broken into smaller pieces, if desired.
• This activity is a great introduction to rocks, minerals and fossils.
• Have students collect and identify local rock, mineral and fossil samples.
• Have students research the various uses for rocks and minerals in our everyday lives.
• Have students research and describe what index fossils are.

Answers to Questions

1. What is the difference between a rock and a mineral?

   Rocks are mixtures of minerals that change over time by a variety of chemical and physical processes. Minerals are naturally occurring, nonliving solids with definite structure and composition.

2. What are the three types of rocks? How is each formed?

   Igneous—formed by the cooling of molten material from volcanic activity
   Sedimentary—formed when sediments become pressed or cemented together or when sediments fall out of solution.
   Metamorphic—formed due to change of temperature and/or pressure increases.

3. How are minerals classified?

   Minerals can be classified in a variety of ways, such as color, hardness, luster, transparency, and chemical reactivity, to name a few.

4. What are the six types of crystal structures found in minerals? Research and list a mineral example for each type of crystal structure.

   Cubic—Halite
   Orthorhombic—Aragonite
   Tetragonal—Zircon
   Monoclinic—Gypsum
   Hexagonal—Quartz
   Triclinic—Plagioclase

5. What is a gemstone?

   Minerals that can be cut or polished to an attractive appearance are known as gemstones.

6. List two types of fossils and describe how each is formed.

   One type of fossil is an impression fossil. Impressions occur when the dead organism leaves an imprint in sedimentary rock. The animal or plant material decays away, but the pattern of the organism’s body remains as the sedimentary rock forms around it. Other fossils may be formed when the original material is replaced by minerals. These types of fossils are known as petrified remains and are hard and rock-like.

Introduction

Identify and classify rocks, minerals and fossils using this hands-on activity.

Concepts

• Rocks
• Minerals
• Fossils

Background

Rocks are mixtures of minerals such as quartz, feldspar, mica and calcite, to name a few. The rock cycle shows how rocks change over time by a variety of physical and chemical processes (see Figure 1). Natural processes that are part of the rock cycle include weathering, erosion, lithification, metamorphism, melting and cooling. Weathering involves both the chemical and physical breakdown of rock at or near the Earth’s surface. This results in the accumulation of sediments—loose materials, such as rock and mineral fragments or pieces of animal and plant remains, that have been transported. Lithification is the transformation of sediment into a rock. The main processes involved in lithification are cementation—large sediments are held together by natural cements, and compaction—layers of sediments are compressed by the weight of the layers above them. Metamorphism is the process by which rocks are changed by heat, pressure, shear, stress or chemicals. Rocks are classified into three distinct groups—igneous, metamorphic or sedimentary—based on how they are formed.

Igneous rocks (the most abundant type of rock on Earth) are formed by the cooling of molten material from volcanic activity. Magma that is trapped below the Earth’s surface is insulated by the rocks surrounding it. This holds in the heat and causes the magma to cool slowly. As the magma cools slowly, the atoms have enough time to arrange into large crystals called mineral grains. The mineral grain size is determined by how fast the magma cools. Rock forms as these mineral grains grow together. The most common minerals found in igneous rocks are feldspar, quartz and biotite. Feldspar is generally a white or chalky-looking grain, quartz is a dark-gray glassy grain, and biotite is a small black grain. Intrusive igneous rocks grow deep below the Earth’s surface, are cooled very slowly and have a large grain size. Extrusive igneous rocks are formed when lava cools at or near the Earth’s surface. When lava cools on the Earth’s surface, it is exposed to air and moisture. Lava cools very quickly under these conditions, hence, only small mineral grains will form. Sometimes extrusive igneous rocks cool so rapidly that there is no time for crystals to form. This gives rocks of this type a glassy appearance. Other extrusive igneous rocks form as gas bubbles pop which gives them a bubbly or vesicular appearance.

Sedimentary rocks form when sediments become pressed or cemented together or when sediments fall out of solution. Sediments are moved by erosion to a new location where they are deposited. As layer upon layer of sediment settles in this location, pressure from the upper layers pushes down on the lower layers. The sediment then sticks together and forms solid sedimentary rock. There are three types of sedimentary rock—clastic, organic and chemical. Clastic sedimentary rocks are made of broken fragments of other rocks. These sediments are compacted and cemented together. Organic sedimentary rocks form from the remains of once-living things. Chemical sedimentary rocks form from minerals dissolved in solution.

Metamorphic rocks are rocks that have changed due to temperature and/or pressure increases. Metamorphic rocks may be formed from changes in igneous, sedimentary or other metamorphic rocks. When mineral grains flatten and line up in parallel bands, a metamorphic rock will have a foliated or banded texture. In some metamorphic rocks, no banding occurs. The mineral grains change, grow and rearrange but they do not form bands. This process produces a non-foliated texture.

Minerals are naturally occurring, nonliving solids with definite structure and composition. Minerals can be classified in a variety of ways, such as color, hardness, luster, transparency, and chemical reactivity. Most minerals are composed of crystals. Crystals are solids in which the atoms are arranged in repeating patterns. The six crystal patterns that may be seen in minerals are cubic, tetragonal, hexagonal, orthorhombic, monoclinic and triclinic (see Figure 2). Minerals that can be cut or polished to an attractive appearance are known as gemstones and are highly prized because they are rare and very beautiful. Some common gemstones are—amethyst, diamond, emerald, feldspar, garnet, hematite, olivine, pyrite, ruby, sapphire, tanzanite and turquoise, to name a few.

Fossils are the remains or traces of once-living organisms. One type of fossil is an impression fossil. Impressions occur when the dead organism leaves an imprint in sedimentary rock. The animal or plant material decays away, but the pattern of the organism’s body remains as the sedimentary rock forms around it. Other fossils may be formed when the original material is replaced by minerals. These types of fossils are known as petrified remains and are hard and rock-like. Certain regions of the world contain large amounts of fossils. A majority of these places are areas where much siltation occurred such as ocean floors and other bodies of water. In many cases, the fossil is not of a complete plant or animal. This may be due to uneven decay of a complete specimen or, in the case of some mollusks—especially bivalves, only half of the shell remains after predation.

Experiment Overview

In this activity, various rocks, minerals and fossils will be excavated from sand, identified and classified.

Materials

Safety Precautions

Follow all normal laboratory guidelines. Wash hands thoroughly with soap and water before leaving the laboratory.

Procedure

1. Obtain a geology sample container containing a specimen mixture from the instructor.
2. Obtain a Specimen Identification Key, Rock Sorting Sheet, Mineral Sorting Sheet, Fossil Sorting Sheet, two magnifying glasses and two plastic dishes for your group.
3. Dig through the sand in the geology sample container to find the geology specimens.
4. Spread the Rock Sorting Sheet, Mineral Sorting Sheet, Fossil Sorting Sheet out on the tabletop.
5. Use the Geology Specimen Identification Key to identify each of the geology specimens from the geology sample container.
6. Place each geology specimen on the correct spot on the sorting sheets.
7. Record the type of each specimen—Rock, Mineral or Fossil—along with each specimen’s characteristics in the data table.
8. When all specimens have been identified and information listed in the data table, have the instructor check your group’s sorting sheets.
9. Answer the Post-Lab Questions.

Student Worksheet PDF

13548_Student1.pdf