Metamorphic Lab 1
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Des Moines Area Community College *
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Course
101
Subject
Geology
Date
Dec 6, 2023
Type
docx
Pages
4
Uploaded by GrandJaguar2398
Metamorphic Lab.
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A.
Analyze the metamorphic rocks below (and actual rock samples of them if available). Beneath or beside each picture, write words that describe the rock's composition (what it is made of), and texture (the size, shape, and arrangement of its parts).
Use your current knowledge and complete the worksheet with your current level of ability.
Do not look up terms or other information. All samples ×1.
1. Since there are alternating bands of light and dark color, this rock is gneiss. This high-grade metamorphic rock forms when it is exposed to high temperatures. and pressures during phyllite formation. Composition could include biotite and quartz.
2. Due to the visible thin layering and folding, this rock may be Phyllite. It is low-grade metamorphic rock that forms when. shale is exposed to low pressure and temperature conditions.
Flaky minerals like mica or clay minerals could make up the composition.
3. Given the presence of white calcite crystals in the rock, this stone may be marble. When limestone is exposed to high pressure and temperature conditions, high-grade metamorphic rock is formed. Calcite could be the composition.
4. This rock may be slate because of the extremely uncommon layering that appears when low pressure and temperature conditions are applied to shale and lead to low grade metamorphism. Clay minerals could make up the composition.
5. This rock may be schist because of the layering of micaceous minerals that occur during medium-grade metamorphism, when phyllite is exposed to pressure and temperature and the composition may consist of mica and clay minerals.
6. Given the lack of layering that results from high pressure and temperature conditions applied to gneiss or any other metamorphic rock, this rock may be granulite. And the composition could be garnet, quartz, or omphacite.
B.
Reflect on your observations and descriptions of sedimentary rocks in part A. Then describe how you would classify the rocks into groups. Be prepared to discuss your classification with other geologists. Based on the observations made, the rocks can be classified as follows:
Rock Name
Texture Grain Size
Parent Rock
Phyllite
Foliated
Fine
Slate
Schist
Fine-grained
Phyllite
Gneiss
Medium-grained
Schist
Quartzite
Non-foliated
Coarse
Quartz Sandstone
A.
Analyze these samples of sedimentary limestone and metamorphic marble.
1.
Calcite is the main component of marbles and limestones. The mineral calcite has the chemical formula CaCO3. An acid test can be used to confirm the presence of the mineral
calcite.
2.
Marble is a metamorphic rock, whereas limestone is a sedimentary rock. Both rocks have different textures, which is obvious. Marble has a uniform texture with crystal banding and veining, whereas limestone has a fine-grained to coarse-grained texture. In contrast to
limestone, which lacks crystals, marble has well-defined crystals with an exquisite appearance.
A.
Describe the change in grain size from slate to schist.
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1.
The increasing influence of the metamorphosis process on the internal composition of the
rock can be used to explain the change in grain size from slate to schist.
Slate: A low-grade metamorphic rock with extremely fine-grained characteristics. The unaided eye is unable to see the grains. Phyllite is a moderately sized metamorphic rock that is in the intermediate stage. The rock has a fine-grained texture that is visible to the unaided eye.
Schist is a large-grained, coarse-grained metamorphic rock of high grade. The unaided eye can see the grains.
2.
A noticeable alignment of fine-grained crystal particles can be seen in phyllite, a relatively fine-grained rock. Schist, on the other hand, has coarser grain size and texture, which results in a unique foliation.
3.
. Foliation produces the parallel arrangement of minerals like mica. Foliation, or the arrangement of minerals in parallel layers, is a crucial feature of metamorphic rock. During the metamorphosis process, the direction in which heat and pressure are applied affects the arrangement of minerals in parallel layers.