TCNJ Physics 120 Introduction to Geology Laboratory Manual Professor Gregory C. Herman hermang@tcnj.edu 1
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TCNJ Physics 120-C Introduction to Geology Lab Manual Laboratory 1 Time-Life-Man.jpg One page, hand-written essay on your interpretation of the handout. 3
Laboratory 2 Minerals and Spectroscopy This lab is an introduction to minerals and spectroscopy, the latter being the scientific study of how light interacts with solid matter. The Ward s mineral sets contain different mineral samples that are found in all different rock types, including those formed during 1)the cooling of molten magma into igneous rock, and others from 2)the precipitation of minerals from a) saturated, briny fluids or b) biological processes. By the end of this lab you should have a working familiarity with the 5 most common rock-forming minerals (quartz, feldspar, mica, amphibole, and pyroxene) and be able to identify them separately from other minerals that appear similar but are usually softer and formed from precipitation ((b) above) 4
Laboratory 2 Minerals 5
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Laboratory 2 Minerals Carbonates(CO 3 )-2 derived from the shells and hard parts of marine organisms or are precipitated as seawater evaporates Calcite (CaCO 3 ) is the main constituent in the sedimentary rock limestone Sulfates (SO 4 )-2 derived from hydrothermal activity or are precipitated as saline-water evaporates Gypsum (CaSO 4. H 4 O) is a main constituent in drywall Phosphates(PO 4 )-3 derived from hydrothermal activity and igneous processes Turquoise CuAl 6 (PO 4 ) 4 (OH) 8 5H 2 O 8
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Laboratory 2 Minerals Mohs Hardness Scale 12
Laboratory 2 Minerals Silicate Minerals 13
Laboratory 2 Minerals Quartz No. 2 of the 5 most common rock-forming (silicate) minerals GCH Rev. 2016-17 1.012-2015 14
Laboratory 2 Minerals Identify quartz, calcite, and gypsum by checking the type of habit, cleavage, and visual aspects that you observe NOTES: Quartz (silica SiO4) Calcite (carbonate CaCO3) Gypsum (sulfte SiO4) 15
Laboratory 2 Minerals FELDSPAR No. 1 of the 5 most common rock-forming (silicate) minerals Group of rock-forming tectosilicate minerals which make up as much as 60% of the Earth's crust. Two cleavage directions at 90 0. Hardnesss of 6 6.5. Will not scratch glass or quartz. Alkali feldspars (K,Na)AlSi 3 O 8 Microcline and orthoclase Not usually clear. Often salmon pink or white and milky. Can also be aqua blue. Can have wavy stripes of similar color that go through the mineral. Plagioclasefeldspars (Na,Ca)AlSi 3 O 8 Albite to Anorthite solid-solution series Individual crystals a range of colors between white and dark gray. Exhibits striations Can have wavy stripes of similar color that go through the mineral. www.earthguide.ucsd.edu/mystery_detectives/media/flash/minerals_igneous/minerals_igneous.swf 16
Laboratory 2 Minerals 17
Laboratory 2 Minerals 18
Laboratory 2 Minerals Identify plagioclase and alkali feldspar by color, microscopic twinning, and mineral habit, hardness with respect to quartz and metal. Note any visual and physical aspects that you observe. NOTES: Plagioclase feldspar (silicate (Na,Ca)AlSi 3 O 8 ) Twinning seen on face of large plagioclase sample Alkali feldspar (K,Na)AlSi 3 O 8 ) 19
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Laboratory 2 Minerals 21
Laboratory 2 Minerals 22
Laboratory 2 Minerals Identify the following minerals by color,and mineral habit, hardness with respect to quartz and metal and one another. Note any distinctive visual and physical aspects that you observe. NOTES: Mica (biotite and muscovite) Pyroxene Amphibole Olivine/peridotite 23
Laboratory 2 Part B Spectroscopy www.impacttectonics.org/gcherman/downloads/phy120c/ 24
Laboratory 3 Igneous Rocks Rocks are identified by their textures, colors, and other physical properties like hardness, weight (density or specific gravity), magnetism (magnetite), and reactivity with acids (limestone and marble). Two rock sets are presented for this lab. The Green buckets contain intrusiveand extrusivesamples of felsic, intermediate, and mafic igneous rocks. The Ward s mineral sets contain different mineral samples that are found in all different rock types, not just igneous ones. By the end of this lab you should have a working familiarity with the 5 most common rock-forming minerals (quartz, feldspar, mica, amphibole, and pyroxene) and be able to identify them both in mineral form and in some of the felsic and intermediate igneous rocks. 25
Laboratory 3 Igneous Rocks Parent magma composition largely determines the composition of igneous rocks but a single magma can, however, yield different rock types. os oxidation state +1 os +2 os An element having a +2 os(or charge) has a higher electron affinitybecause it has twice the charge than one with a +1 os. Calcium and magnesium (+2) are proportionately more abundant in mafic rocks that crystallize form magma first with slow cooling and crystal growth. 26
Laboratory 3 Igneous Rocks Texture in igneous rocks is related to cooling history; the slower the magma cools, the more coarse-grained the rock becomes. 27
Laboratory 3 Igneous Rocks Typically, the coarsest-grained rocks formed in deep crustal chambers after rising out of the mantle where it can accumulate and pond at the base of the crust or in the crust, or deep in the roots of crustal mountain where rocks begin to melt from burial and heat. They become exposed at the surface Eons after formation from crustal tectonics. 28
Laboratory 3 Igneous Rocks 29
Laboratory 3 Igneous Rocks 30
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Laboratory 3 Igneous Rocks SS -red sandstone B -basalt dike leading to basalt flow D -diorite stock and sills Gr granite Pg pegmatite Gb Gabbro 32
Laboratory 3 Igneous Rocks NOTES: 33
Laboratory 5 Sedimentary and Metamorphic Rocks LAB 5 provides samples of all three principal groupings of rocks including: 1) Igneous (plutonic and extrusive felsic, intermediate, and mafic varieties) 2) Sedimentary (detrital and chemical) and 3) Metamorphic (low, medium, and high grade) Because we studied igneous rocks in LAB3, this will serve as a review for those, but our focus in this lab will be the different types and subtypes of sedimentary and metamorphic rocks and how they compare to igneous rocks, to one another, and with respect to the rock cycle. 34
Laboratory 5 Sedimentary and Metamorphic Rocks LAB 5 is set up with all three groups of rocks arranged on laboratory tables 1 to 6. Each group will systematically move to adjacent tables in a clockwise rotation to study the rocks at each station for ~20-minute intervals. MEDIUM- TO HIGH-GRADE METAMORPHIC VOLCANIC IGNEOUS 4 5 6 3 LOW-GRADE METAMORPHIC 2 DETRITAL SEDIMENTARY 1 CHEMICAL SEDIMENTARY 35
Laboratory 5 Table 1. Sedimentary Rocks The two primary types of sediment are chemical (table 1) anddetrital (table 2) Sediment becomes lithified into sedimentary rocks by cementation and compaction. Chemical sedimentconsists of minerals precipitated from solution by inorganic processes and by the activities of biological organisms. Chemical sedimentary rocks (limestone, coal, microcrystalline quartz) are formed from chemical sediment. Detrital sedimentconsists of solid particles, products of mechanical weathering. Detrital sedimentary rocks are formed from detrital sediment 36
Laboratory 5. Table 1, Chemical Sedimentary Rocks Chemical sedimentary rocks are: a) Precipitated directly from fresh or sea water by biological accumulation, b) Precipitated from saturated water (fresh, marine, and hydrothermal), or c) Formed in bogs or swamps from the accumulation of dead organic matter (animal and vegetation) 37
Laboratory 5. Table 1, Chemical Sedimentary Rocks Checklist: Limestone (CaCO 3 in it s pure form) is generally soft, gray to cream colored, will react with HCL, and is softer than metal, and can contains marine fossils. Dolomite is similar to limestone but is commonly has some Mg +2 replacing Ca +2, can have an orange tint from also having some Fe +2, is slightly harder than limestone, is less reactive to HCL For coal, recognize the peat lignite coal transition and the bituminous versus anthracite types. Bituminous is lower grade, has more sulfur (yellow mineral) and is not as shiny. Antraciteof higher grade as it burenscleaner and gives off more energy. Differentiate among cryptocrystalline quartz and limestone that are precipitated out of hydrothermal solutions or saturated waters. 38
Laboratory 5. Table 2, Detrital Sedimentary Rocks Detrital sedimentary rocks are transported and deposited by running water, wind, or glacial ice. Most are composed of silica grains and/or mineral and rock fragments, and are therefore differentiated using grain size. Common cementing agents are silica and calcium carbonate. 39
Laboratory 5. Table 2, Detrital Sedimentary Rocks 40
Laboratory 5. Table 2, Detrital Sedimentary Rocks Checklist: Recognize increasing grain size of mudstone siltstone sandstone conglomerate. Mudstone and shale differ because the latter has initial layering, or fissility, by the preferred alignment of play minerals during early phases of burial and compaction. The degree of rounding and sorting of grains in the various samples and discuss the significance with respect to transport distance. Conglomerate contains rounded grains whereas breccia contains angular grains Those cemented with calcium carbonate are commonly more friable and can react with dilute HCL whereas silica-cemented ones are harder and nonreactive to HCL. 41
Laboratory 5. Sedimentary and Metamorphic Rocks Note: Metamorphic rocks form when minerals in a sedimentary or igneous rocks rock begin to recrystallize into ne mineral forms when it is subjected to changes (usually increases) in temperature and pressure from burial or through interaction with groundwater. The transition from sedimentary rocks into low-grade metamorphic rocks is gradual as rocks become more deeply buried and heated through time, therefore it is sometimes difficult to tell if a mudrock is sedimentary or low-grade metamorphic without microscopy. Similarly the transition from limestone into a marble sometimes requires microscopic work. Generally speaking, metamorphic rocks are more compact and dense than their sedimentary precursor rocks, have foliation caused by mineral banding or layering that can be seen with the naked eye. But this isn t the case for pure quartz or limestone rocks that can be mono-minerallicand therefore locally lack visible foliation. 42
Laboratory 5. Table 3, Low-grade Metamorphic Rocks Metamorphic rocks are a result of new mineral growth as a result of changing temperature and temperatures during burial, tectonism, and plutonic igneous activity. Mostly foliated to non-foliated silica and lime rocks that are more dense, hard, and mineralized than sedimentary rocks. Do not ordinarily include plutonic igneous rocks because igneous minerals form at relatively high T & P s. 43
Laboratory 5. Table 3, Low-grade Metamorphic Rocks Checklist: Hornfels are sedimentary rocks that have been altered and mineralized by hydrothermal solutions percolating through them. The transition of lime rocks to different types of marble (foliated and non-foliated) Those cemented with calcium carbonate are commonly more friable and can react with dilute HCL whereas silica-cemented ones are harder and nonreactive to HCL. The transition from sandstone to quartzite (foliated and non-foliated). Quartzite and marble can look very similar, but metal scratches marble but not quartzite. The transition of mudrocksfrom mudstone argillite phyllite 44
Laboratory 5. Table 4, Medium-grade Metamorphic Rocks Schist is a medium-grade metamorphic rock with medium to large, flat, sheetlike grains in a preferred orientation (nearby grains are roughly parallel). It is defined by having more than 50% platy and elongated minerals, often finely interleaved with quartz and feldspar. 45
Laboratory 5. Table 4, High-grade Metamorphic Rocks Gneissis a high grade metamorphic rock, meaning that it has been subjected to higher temperatures and pressures than schist. It is formed by the metamorphosis of granite, or sedimentary rock.gneissdisplays distinct foliation, representing alternating layers composed of different minerals. Migmatiteis a rock that is a mixture of metamorphic rock and igneous rock. It is created when a metamorphic rock such as gneiss partially melts, and then that melt recrystallizes into an igneous rock, creating a mixture of the unmeltedmetamorphic part with the recrystallized igneous part. 46
Laboratory 5 Crustal rocks A. B. garnet C. GCH 02-2016 47
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