Lab 6 Geology

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Rowan University *

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06103

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Geology

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Dec 6, 2023

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Lab 6 Metamorphic Rocks CE 342 Geology Dr. John Schuring Spring 2023 1) Briefly explain the difference between foliated and nonfoliated metamorphic rocks, including their formative environments and textures. Give three examples of each. When temperature and pressure apply to a Igneous or sedimentary rock it will convert to metamorphic rock. And the minerals like platy and elongated minerals are arranged in a plane called foliation surface or we can say a rock is foliated. The non foliated rocks are those which have no platy minerals. The main platy minerals are mica and amphibole. 2) When a metamorphic rock forms from a “parent” igneous or sedimentary rock, it tends to follow a specific sequence or series. List the metamorphic series for the following rocks: Shale, Sandstone, Limestone, and Basalt. Going from: Shale to Schist Sandstone to Quartzites Limestone to Marble Basalt to greenschist All these parent rocks become metamorphic rocks in their respective temperature and pressure conditions. 3) Which metamorphic rock(s) will react to dilute hydrochloric acid. Also, indicate whether or not the rock surface needs to be powdered. Marble is limestone that has undergone metamorphosis. The mineral calcite is found in limestone, which is a sedimentary rock. When a drop of weak hydrochloric acid is dropped on the rock, it bubbles and fizzes, releasing carbon dioxide. This means that the rock is made up of calcite. To produce an observable reaction, minerals like calcite and dolomite must be powdered. 4) In a metamorphic rock, how is the orientation of foliation related to stress? The preferred orientation of phyllosilicates, such as clay minerals, micas, and chlorite, causes the majority of foliation. When a rock is deformed under directed pressure during metamorphism, the minerals may become elongated in the direction perpendicular to the main stress. Foliation is then formed as a result of this. 5) Is contact metamorphism likely to produce foliated rocks? Why? No, because the pressure in regional metamorphism causes the minerals to re-align into layers. This is because contact metamorphism occurs when a rock is close enough to a magma
chamber to reach extremely high temperatures without melting. This changes the bonds of the minerals in the rock to create crystals. 6) When marble and quartzite are encountered in the field, they have a similar appearance. What two tests could you use to tell them apart? Marble and quartzite can be very similar in appearance. Fortunately, there are a couple of simple tests one can perform to tell the difference between them: the scratch test and the acid test. 7) Metamorphic Foliation. Name the kinds of foliation depicted below A. Slate B. Phyllitic 8) Identifying Veins: A short video is posted in Canvas demonstrating a lab test of an actual vein. Use the information in your course materials to identify the mineralogy of the vein. Explain the process and reasoning that you used. Veins are dilated fractures which are filled by minerals. The deposits in veins may be quartz, calcite or carbonate minerals which can be found in all sorts of rocks. The thickness of the vein may vary from a millimeter to several meters. Veins provide information on stress, strain, temperature, pressure, fluid composition, etc. 9) 15-Specimen Collection: Examine the identified metamorphic rock collection provided. Compare the specimens with the information in the Table 3.3.1, Figure 3.3.5, and the Course Notes, and then fill in the information in the table below. Specimen No. Rock Name Texture (Foliated/ Non-foliated) Foliation Description (if foliated) Metamorphic Grade (low/medium/ high) Other Observations 1 Gneiss Foliated Gneissic Med - High Has quartz and mica 2 Graphite Schist Foliated Slaty High Very dark mineral 3 Muscovite Schist Foliated Schistic Med - High Very small mineral 4 Garnet Schist Foliated Schistic Med Fine grained mineral 5 Chlorite Schist Foliated Schistic Low Has Quartz and Feldspar
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