Lab: Igneous Rocks
Lab Activity 5.7 - Practice in Describing and Identifying Igneous Rocks Part E - The Wildcard of the Mafic Color Index
Answer is the Image.
Lab Activity 5.6.1 - Sampling Minerals to Estimate Rock Composition Part C - Placement of a Point Count Line within a Pegmatite The lab activity in your book asked you to perform a point count of minerals along a single line within two different rocks. The following exercise asks you to count the minerals that lie along two different lines (marked in red) within the same rock, so that the results may be compared for accuracy. Individual minerals along the lines are labeled with numbers for ease of viewing. Each individual crystal is labeled with a number. Black numbers label white and pastel crystals.
1. 3 of the 4 minerals along the point count line of the pegmatite on the left are the white and pinkish/orange pastel minerals. 2. 1 of the 4 minerals along the point count line of the pegmatite on the left are the black/dark green minerals. 3. 6 of the 10 minerals along the point count line of the pegmatite on the right are the white and pinkish/orange pastel minerals. 4. 4 of the 10 minerals along the point count line of the pegmatite on the right are the black/dark green minerals.
Lab Activity 5.6.1 - Sampling Minerals to Estimate Rock Composition Part A - Placement of a Point Count Line within a Granite Lab Activity 5.6 in your book asked you to perform a point count of minerals along a single line within two different rocks. The following exercise asks you to count the minerals that lie along two different lines (marked in red) within the same rock, so that the results may be compared for accuracy. Individual minerals along the lines are labeled with numbers for ease of viewing, and each individual crystal is labeled with a number (black numbers label white and pastel crystals).
1. 7 of the 8 minerals along the point count line of the granite on the left are the light gray, white, and pinkish/orange pastel minerals. 2. 1 of the 8 minerals along the point count line of the granite on the left are the black minerals. 3. 7 of the 9 minerals along the point count line of the granite on the right are the light gray, white, and pinkish/orange pastel minerals. 4. 2 of the 9 minerals along the point count line of the granite on the right are the black minerals.
Lab Activity 5.4.1 - The Minerals of Igneous Rocks In Activity 5.4, eight minerals that are commonly found in igneous rocks were identified, described, and their chemical compositions were found from the section 'Mineral Composition of Common Igneous Rocks' on page 123. You will use this information and the mineral photographs on page 138 to identify mineral types within four examples of igneous rocks in order to ultimately infer the rocks' compositions. Next, you will use the composition of minerals to determine if these minerals are felsic or mafic. Part B - Identifying Minerals in Igneous Rocks 2 Which of the following minerals listed below, found also on page 138, is represented by the green crystals in the igneous rock below?
Olivine
Lab Activity 5.6.1 - Sampling Minerals to Estimate Rock Composition Part B - Comparison of Results: Granite Recall that black minerals in igneous rocks are mafic minerals. In Part A, the line in the granite on the left had 1 black mineral out of the 8 total minerals, indicating that 12.5% of the minerals along this line were mafic. The line in the granite on the right had 2 black minerals out of the 9 total minerals, indicating that 22.2% of the minerals along this line were mafic. While black minerals within a rock are mafic, the rock as a whole when all minerals along the line may be light(leucocratic), medium(mesocratic), dark(melanocratic), or entirely dark. What conclusions regarding the composition of this granite do these lines draw? The table on page 126 in the lab manual may be helpful.
Both lines indicate that the granite is leucocratic.
Lab Activity 5.3 - Recognizing Glassy and Vesicular Textures within Igneous Rocks An experiment was performed in Activity 5.3 that synthesized a solid mass of sugar, which demonstrated both glassy and vesicular textures. Apply your observations of this model to identify glassy and vesicular textures in photographs of igneous rocks. Next, identify the exact qualities that comprise glassy and vesicular textures by examining a rock that lacks these qualities. Part F - Why a Rock May Be Neither Glassy Nor Vesicular Please examine the rock photograph provided and select ALL of the correct reasons why it shows neither a glassy nor a vesicular texture. What are the reasons that this rock possesses neither a glassy texture nor a vesicular texture?
This rock does not contain any visible holes. This rock does not have a glassy luster. This rock does not possess a conchoidal fracture.
Lab Activity 5.3 - Recognizing Glassy and Vesicular Textures within Igneous Rocks An experiment was performed in Activity 5.3 that synthesized a solid mass of sugar, which demonstrated both glassy and vesicular textures. Apply your observations of this model to identify glassy and vesicular textures in photographs of igneous rocks. Next, identify the exact qualities that comprise glassy and vesicular textures by examining a rock that lacks these qualities. Part C - Glassy, Vesicular, or Neither? Rock 3 Please indicate whether the rock pictured below possesses a glassy texture, a vesicular texture, or neither texture. The texture of this rock is:
Vesicular
Lab Activity 5.3 - Recognizing Glassy and Vesicular Textures within Igneous Rocks An experiment was performed in Activity 5.3 that synthesized a solid mass of sugar, which demonstrated both glassy and vesicular textures. Apply your observations of this model to identify glassy and vesicular textures in photographs of igneous rocks. Next, identify the exact qualities that comprise glassy and vesicular textures by examining a rock that lacks these qualities. Part E - Glassy, Vesicular, or Neither? Rock 5 Please indicate whether the rock pictured below possesses a glassy texture, a vesicular texture, or neither texture. The texture of this rock is:
Vesicular
Lab Activity 5.7 - Practice in Describing and Identifying Igneous Rocks Part B - Describing and Identifying Igneous Rocks: Rock 2 Describe the photograph of the rock below based on its texture and composition by completing the sentences. Then, use this data to identify the rock and indicate if it is formed intrusively or extrusively. Figure 5.21 and Figure 5.22 in your lab manual can help you with these tasks.
1. The texture of this rock is aphanitic. 2. The composition of this rock falls into the mafic category. 3. Based on the rock's texture and its composition (i.e., the minerals present and the Mafic Color Index of the rock), the name of this rock is basalt. 4. Based on the rock's texture, the rock cooled within an extrusive origin.
Lab Activity 5.7 - Practice in Describing and Identifying Igneous Rocks Part C - Describing and Identifying Igneous Rocks: Rock 3 Describe the photograph of the rock below based on its texture and composition by completing the sentences. Then, use this data to identify the rock and indicate if it is formed intrusively or extrusively. Figure 5.21 and Figure 5.22 in your lab manual can help you with these tasks.
1. The texture of this rock is glassy. 2. Based on the rock's texture, the name of this rock is obsidian. 3. Based on the rock's texture, the rock cooled within an extrusive origin.
Lab Activity 5.7 - Practice in Describing and Identifying Igneous Rocks Part A - Describing and Identifying Igneous Rocks: Rock 1 Describe the photograph of the rock below based on its texture and composition by completing the sentences. Then, use this data to identify the rock and indicate if it is formed intrusively or extrusively. Figure 5.21 and Figure 5.22 in your lab manual can help you with these tasks.
1. The texture of this rock is phaneritic. 2. The composition of this rock falls into the felsic category. 3. Based on the rock's texture and its composition (i.e., the minerals present and the Mafic Color Index of the rock), the name of this rock is granite. 4. Based on the rock's texture, the rock cooled within an intrusive origin.
Lab Activity 5.7 - Practice in Describing and Identifying Igneous Rocks Part D - Describing and Identifying Igneous Rocks: Rock 4 Describe the photograph of the rock below based on its texture and composition by completing the sentences. Then, use this data to identify the rock and indicate if it is formed intrusively or extrusively. Figure 5.21 and Figure 5.22 in your lab manual can help you with these tasks.
1. The texture of this rock is vesicular. 2. The composition of this rock falls into the mafic category. 3. Based on the rock's texture and its composition (i.e., the minerals present and the Mafic Color Index of the rock), the name of this rock is scoria. 4. Based on the rock's texture, the rock cooled within an extrusive origin.
Lab Activity 5.2 - Crystal Textures of Igneous Rocks In Activity 5.2, you explored the properties and formation conditions of various crystal textures of igneous rocks. In this exercise, you will compare and contrast these textures to each other, and then relate their appearances to the locations of the formations of rocks with these textures. Part B - Identifying Crystal Textures of Individual Igneous Rocks: Rock 1 Having ranked the following igneous rock with other igneous rocks based on the sizes of their mineral crystals, please indicate the name of the crystal texture within the rock below.
Aphanitic
Lab Activity 5.4.1 - The Minerals of Igneous Rocks In Activity 5.4, eight minerals that are commonly found in igneous rocks were identified, described, and their chemical compositions were found from the section 'Mineral Composition of Common Igneous Rocks' on page 123. You will use this information and the mineral photographs on page 138 to identify mineral types within four examples of igneous rocks in order to ultimately infer the rocks' compositions. Next, you will use the composition of minerals to determine if these minerals are felsic or mafic. Part F - Correlating Mineral Color to Its Composition The picture below shows the correct solution to the previous question, which asked you to sort minerals into the categories felsic and mafic based on their chemical compositions. Based on this picture, please determine which of the sentences below is true.
Felsic minerals are generally lighter in color than mafic minerals.
Lab Activity 5.3 - Recognizing Glassy and Vesicular Textures within Igneous Rocks An experiment was performed in Activity 5.3 that synthesized a solid mass of sugar, which demonstrated both glassy and vesicular textures. Apply your observations of this model to identify glassy and vesicular textures in photographs of igneous rocks. Next, identify the exact qualities that comprise glassy and vesicular textures by examining a rock that lacks these qualities. Part A - Glassy, Vesicular, or Neither? Rock 1 Please indicate whether the rock pictured below possesses a glassy texture, a vesicular texture, or neither texture. The texture of this rock is:
Glassy
Lab Activity 5.3 - Recognizing Glassy and Vesicular Textures within Igneous Rocks An experiment was performed in Activity 5.3 that synthesized a solid mass of sugar, which demonstrated both glassy and vesicular textures. Apply your observations of this model to identify glassy and vesicular textures in photographs of igneous rocks. Next, identify the exact qualities that comprise glassy and vesicular textures by examining a rock that lacks these qualities. Part D - Glassy, Vesicular, or Neither? Rock 4 Please indicate whether the rock pictured below possesses a glassy texture, a vesicular texture, or neither texture. The texture of this rock is:
Glassy
Lab Activity 5.6.1 - Sampling Minerals to Estimate Rock Composition Part E - Comparing the Color of Peridotite to Its Composition Below is a photograph of the igneous rock, peridotite. The photo shows that the rock is mostly a medium shade of green, but what do you know about peridotite's composition? Pages 81-85 and 129 can help you select all four correct statements about peridotite's composition below.
Has an ultramafic composition Is mostly comprised of olivine, a light to medium green mineral Is mostly comprised of olivine, a mafic mineral {In general, the darker in color an igneous rock is, the higher its content of mafic (iron- and magnesium-bearing) minerals. However, peridotite is a generally light to medium green rock that has such a high content of iron and magnesium (due to it being mainly comprised of the mineral olivine) that it falls into the ultramafic category. Peridotite is an exception to the "darker color = more mafic" generalization.}
Lab Activity 5.3 - Recognizing Glassy and Vesicular Textures within Igneous Rocks An experiment was performed in Activity 5.3 that synthesized a solid mass of sugar, which demonstrated both glassy and vesicular textures. Apply your observations of this model to identify glassy and vesicular textures in photographs of igneous rocks. Next, identify the exact qualities that comprise glassy and vesicular textures by examining a rock that lacks these qualities. Part B - Glassy, Vesicular, or Neither? Rock 2 Please indicate whether the rock pictured below possesses a glassy texture, a vesicular texture, or neither texture. The texture of this rock is:
Neither glassy nor vesicular
Lab Activity 5.2 - Crystal Textures of Igneous Rocks In Activity 5.2, you explored the properties and formation conditions of various crystal textures of igneous rocks. In this exercise, you will compare and contrast these textures to each other, and then relate their appearances to the locations of the formations of rocks with these textures. Part D - Identifying Crystal Textures of Individual Igneous Rocks: Rock 3 Having ranked the following igneous rock with other igneous rocks based on the sizes of their mineral crystals, please indicate the name of the crystal texture within the rock below.
Pegmatitic
Lab Activity 5.2 - Crystal Textures of Igneous Rocks In Activity 5.2, you explored the properties and formation conditions of various crystal textures of igneous rocks. In this exercise, you will compare and contrast these textures to each other, and then relate their appearances to the locations of the formations of rocks with these textures. Part C - Identifying Crystal Textures of Individual Igneous Rocks: Rock 2 Having ranked the following igneous rock with other igneous rocks based on the sizes of their mineral crystals, please indicate the name of the crystal texture within the rock below.
Phaneritic
Lab Activity 5.6.1 - Sampling Minerals to Estimate Rock Composition Part D - Comparison of Results: Pegmatite Recall that black minerals in igneous rocks are mafic minerals. In the previous exercise, the line in the pegmatite on the left had 1 black mineral out of the 4 total minerals, indicating that 25% of the minerals along this line were mafic. The line in the pegmatite on the right had 4 black minerals out of the 10 total minerals, indicating that 40% of the minerals along this line were mafic. What conclusions regarding the composition of this pegmatite do these lines individually draw? The table on page 126 in the lab manual may be helpful.
The line in the pegmatite on the left indicates that the pegmatite is leucocratic, whereas the line in the pegmatite on the right indicates that the granite is mesocratic. {The mineral point count lines in the photograph on the right indicate that the pegmatite falls within the mesocratic category of the Mafic Color Index on page 126 in the lab manual. However, these counts only consider the number of mafic minerals along the line, and not the size of the mineral crystals. If you compared the appearance of the overall pegmatite to the Mafic Color Index, you would likely conclude that this is a leucocratic rock (likely a pegmatitic granite) due to the high volume of feldspar (pink/orange crystals) and quartz (white crystals) within the rock.}
