Purpose Compare and Analyze the Composition of Metamorphic Rocks to the Parent Sedimentary

Science 8 Enduring Understanding Laboratory Activity Earth is a dynamic system. Changes result from the interaction between matter and Under Pressure energy. Concepts Important to Know and Understand EQ: Why are constructive forces so properties of matter, changes in Earth systems, internal/external forces, physical and chemical actions destructive? Broad Brush Knowledge Targeted Skills rock cycle, formation of rocks, chemical formulas, periodic  Information Literacy table  Evaluate information  draw conclusions, make inferences, and connections Core Objectives based on information 15. Identify chemical and physical properties used to classify  Thinking and Reasoning matter and determine everyday applications.  Creative thinking 16. Demonstrate that substances may react chemically to  patterns form new substances, which can be represented in a  classify chemical equation.

Purpose Compare and analyze the composition of metamorphic rocks to the parent sedimentary, igneous, or earlier metamorphic rock formations.

Expert Information: Metamorphic rocks started out as other types of rock, but have been substantially changed from their original igneous, sedimentary, or earlier metamorphic form. Metamorphic rocks form when rocks are subjected to hot, mineral-rich fluids, high heat, high pressure, or more commonly, some combination of these factors. Conditions like these are found deep within the earth or where tectonic plates meet. Stresses caused by tectonic plates colliding during the process of mountain building or during times when plates slide past each other, change rocks. All rocks are composed of minerals. These minerals have definite chemical arrangements and are normally stable only under certain conditions. When conditions change in the surrounding areas, the crystal arrangement of the minerals will change. Heat and pressure applied to rocks during the metamorphic process cause the minerals composing them to bend, break, stretch, or reform. Exposure to heat and pressure can reshuffle existing elements to change mineral composition. This process can occur without rocks actually melting, but can cause recrystallization of the minerals that are present. The word metamorphic literally means (meta-) change and (morph) form. This definition very accurately describes this type of rock formation. In metamorphic rocks, some or all of the minerals in the original rock are replaced, atom by atom, forming new minerals. Identifying chemical properties of a rock or mineral is difficult and can be a very involved process. Scientists can more easily identify physical characteristics. When identifying metamorphic rocks, the first characteristic used to aid in identification is banding. If bands or layers form during the metamorphic process, the rocks are classified as foliated. If bands or layers do not occur, the rocks are classified as nonfoliated. These two characteristics are the basis for dividing metamorphic rocks into two subgroups.

Procedure Part 1 1. Observe all three samples of rocks. Carefully describe the characteristics of each sample. In our chart below. 2. Test each rock with one or two drops of hydrochloric acid. 3. Record results. Data Analysis 1. Fill in the chart below identifying the igneous or sedimentary rock each metamorphic rock originated from and explain the reasoning for the choices.

Metamorphic Rock Origins Metamorphic Parent Igneous or Reasons to validate choice Rock Sedimentary Rock Gneiss (Pg. 403)

Quartzite

Marblel

2. Which parent rocks were the easiest to identify? Explain.

3. Explain how two samples of the same metamorphic rock might not look identical.

4. List some difficulties you could encounter when trying to identify certain rock types.

5. Which physical or chemical properties are most useful in classifying rocks? Explain your answers.

6. Both gneiss and marble are used for building materials such as cabinet tops. Explain why gneiss would be a better choice than marble for kitchen cabinet tops where they would be exposed to vinegar, lemon juice, and other acids.