Geology of Table Rock - 8th - On-site Activities 3

Geology of Table Rock - 8th - On-site Activity/Interpreter Led

Grade Level: 8
Content Area: Science
Time to Complete: 70 minutes
Title of Lesson: Common Rocks and Minerals of the Blue Ridge

South Carolina State Standards Addressed:

8-1.1	Design a controlled scientific investigation.
8-1.2	Recognize the importance of a systematic process for safely and accurately conducting investigations.
8-1.3	Construct explanations and conclusions from interpretations of data obtained during a controlled scientific investigations.
8-1.4	Generate questions for further study on the basis of prior investigations.
8-1.5	Explain the importance of and requirements for replication of scientific investigations.
8-1.6	Use appropriate tools and instruments.
8-1.7	Use appropriate safety procedures when conducting investigations.
8-3.4	Explain how igneous, metamorphic, and sedimentary rocks are interrelated in the rock cycle.
8-3.5	Summarize the importance of minerals, ores, and fossil fuels as Earth resources on the basis of their physical and chemical properties.

Lesson Description:

Students will examine several minerals commonly found in Blue Ridge rocks and identify them using a mineral identification key. They will then correlate these minerals to the major rock types found at Table Rock State Park.

Focus Questions for Students:

1.	How can you tell one mineral from another?
2.	Which physical properties are most useful in identifying minerals?
3.	Can two different minerals have the exact same set of physical properties?
4.	How can you use mineral identification data to classify rocks?

Culminating Assessment:

	Students will examine samples of two common rocks from Table Rock State Park.
	They will identify the main minerals present in each sample and classify each rock.

Materials/Equipment/Resources (Per Group):

	samples of common Table Rock State Park rocks (2)
	samples of common Blue Ridge area minerals (9)
	hand lens (3)
	small glass jar (1)
	worksheet (1)
	vocabulary (1)

Teacher Preparation:

1.	Read background information.
2.	Be prepared to describe and discuss the common minerals of the Blue Ridge Region and the main rocks found at Table Rock State Park.
3.	Practice using a hand lens and glass jar for testing and identifying selected minerals, applying the key provided. Be prepared to demonstrate how to safely perform the hardness test on the glass jar.

Background Information:

All minerals have a distinctive set of physical and/or chemical characteristics that can be used to determine their identity. These include (1) hardness – tested by attempting to scratch glass (hardness value 6); (2) cleavage – seen by examination of specimen faces; (3) specific gravity – checked by the heft of a sample; (4) color – good for some but not all; and (5) crystal appearance – the shape of any visible crystals. Several other simple tests may be performed.

Quartz and feldspar are very common in most Blue Ridge rocks (as in many other rocks as well) and can be differentiated by their hardness (both are harder than glass, but quartz is harder than feldspar), cleavage (feldspar has it, quartz does not), and different crystal appearance. The variety of amphibole called hornblende is an iron-rich mineral that dominates one of the two main rock types of the Table Rock area. Its near-black color, cleavage at 56 and 124 degrees, and elongated crystal structure all help to identify it. The mineral augite (pyroxene group) looks very similar to hornblende, but is generally more dark green than black, cleavage angles are 87 and 93 degrees and its crystals are not as elongated. Sheet silicates of the mica group, iron-poor muscovite (light-colored) and iron-rich biotite (dark-colored) are found in some local rocks, most notably schists. Olivine, an olive green to near black mineral that exhibits no cleavage is rarely seen in local rocks. An iron-rich garnet that forms during metamorphism, and has a distinctive dark color and crystal habit, is also prevalent in rocks of this area. Calcite is the only truly important rock-forming mineral not seen in the area at all. It effervesces in dilute hydrochloric acid and has a distinctive rhombohedral crystal structure.

Blue Ridge rocks are composed of various types of igneous and metamorphic rock, especially granite-gneiss and amphibolite, (a very dark banded gneiss with high concentrations of the amphibole mineral hornblende). During metamorphism, pre-existing minerals were totally recrystallized by high temperatures and pressures to create a texture very different from that found in the original rock. In addition to being altered by metamorphism, the rock in the Blue Ridge Region has been severely fractured and folded by tectonic activity.

In general, the higher elevated section of Table Rock Mountain is mostly granite-gneiss and is very resistant to erosion. The lower elevations are generally underlain by the less resistant amphibolite. Vegetation grows more readily on the easily decomposed amphibolite areas.

Procedures:

1.	Arrange students in groups of 2-3.
2.	Students should conduct the tests described by the teacher on each sample mineral. Record your information on the worksheet data table like the example on the worksheet.
3.	Compare your results with the key provided and determine the name of each sample.
4.	Write the mineral name in the last column of the data table. Answer questions 1-7 on worksheet.