Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
CHAPTER 5 ROCKS AND MINERALS WHAT IS A MINERAL??? A naturally formed , inorganic solid that has a definite crystalline structure. TWO GROUPS OF MINERALS • Silicate Minerals – a mineral that contains a combination of silicon, oxygen, and one or more metals. • Nonsilicate Minerals – a mineral that does not contain compounds of silicon and oxygen. • Examples: Quartz, Feldspar, and Mica • Examples: Native elements, Carbonates, Halides, Oxides, Sulfates, and Sulfides. IDENTIFYING MINERALS Using Physical Properties • • • • • • • • • Color Luster Hardness Streak Density Crystal Shape Cleavage Fracture Special properties COLOR • Most obvious way to tell minerals apart but, most unreliable because of impurities found in minerals. • • • • • • Example: Quartz can be: Pink Clear Purple White Black LUSTER • The quality of light reflected by a mineral. • Metallic and nonmetallic are the types of luster. Submetallic. In between • Metallic = shiny • Nonmetallic = vitreous (glassy), earthy (dull), pearly, silky, etc. HARDNESS • Resistance of a mineral to abrasion. • MOH’S HARDNESS SCALE • 1(talc = softest)10(diamond = hardest) • Scratch test. Scratch minerals together, one will scratch the other. If they don’t, they are the same hardness. MOH’S HARDNESS SCALE • • • • • • • • • • 1 Talc 2 Gypsum 3 Calcite 4 Fluorite 5 Apatite 6 Feldspar 7 Quartz 8 Topaz/beryl 9 Corundum 10 Diamond STREAK • The color of the powdered mineral. • More reliable than color • A streak plate is used to perform this test. • Streak plate=Unglazed porcelain DENSITY/SPECIFIC GRAVITY • D=m/v • Weight of a mineral compared to an equal volume of water. • HEFT- Tossing the mineral in your hand. • If a mineral weighs 3 times as much as an equal volume of water, it’s specific gravity is 3. • Most minerals have a specific gravity of 3. CRYSTAL SHAPE/FORM • Internal arrangement of atoms. (without constriction) • 1. Cubic • 2. Hexagonal • 3. Orthorhombic • 4. Monoclinic • 5. Tetragonal • 6. Triclinic CLEAVAGE • The tendency of a mineral to break along smooth definite surfaces. These are planes of weak bonding. Example: mica • Number of planes exhibited and the angles at which they meet. FRACTURE • Minerals that break along irregular surfaces. • May splinter. • Smooth curved surfaces = Conchoidal Fracture. “Glasslike” SPECIAL PROPERTIES • Magnetite = Magnetic • Halite = salty (taste) • Sulfur = smells like rotten eggs (odor) • Calcite = fizzes when HCL is put on it • Fluorite = Glows under UV light • Uraninite = radioactive • Etc. CHAPTER 6 • Rock- A collection of one or more minerals. It can be made of mineral matter that is not crystalline or organic material. Rocks are classified into three major types. WHAT IS A ROCK ? A naturally occurring solid mixture of one or more minerals or organic matter. What is the rock cycle? • The series of processes in which rock changes forms, changes from one type to another, is destroyed, and forms again by geological processes. THE ROCK CYCLE Bowen’s reaction series The simplified pattern that illustrates the order in which minerals crystallize from cooling magma according to their chemical composition and melting point. Mafic=Dark colored rock. Contains magnesium Felsic=Light colored rock. Contains silicon and feldspar. Olivine crystallizes first and quartz last. Bowen’s reaction series 3 TYPES OF ROCKS IGNEOUS Rocks formed from fluid magma within the Earth. Classified according to their composition and texture. Latin: ignis = fire Intrusive = Formed deep within the Earth Extrusive = Formed from lava. (exterior) Examples: Granite, obsidian, pumice, basalt, Intrusive/Plutons Named after Pluto, the god of the underworld Examples: Sills Dikes Laccoliths Batholiths=largest 4 Basic textures 1. fine-grained (aphanitic) – small crystals, cooled quickly. Example= basalt 2. course-grained (phaneritic) – large crystals, cooled slowly. Example= granite 3. porphyritic – large crystals scattered on a background on smaller crystals. 4. glassy- no crystals, cooled instantly. Example= obsidian Composition of igneous rocks Felsic Describes magma or igneous rock that is rich in feldspars and silica and that is generally light in color. Examples: granite, rhyolite, quartz, feldspar, pumice, biotite and muscovite mica Mafic Describes magma or igneous rock that is rich in magnesium and iron and is generally dark in color. Hornblende, olivine, pyroxene, basalt, and gabbro. Ferromagnesian minerals Intermediate Diorite and Andesite Intrusive Igneous Rock structures Batholiths-largest Stocks Laccoliths Sills and dikes Page 133 in textbook. Draw figure 5 into notebooks. Extrusive Igneous rock structures Volcano Volcanic neck Lava flows Lava Tuff- volcanic ash deposit BELLRINGER How are igneous rocks classified?? SEDIMENTARY ► Rocks formed by the compacting and cementing of sediments or by other nonigneous processes at the Earth’s surface. ► Sedimentary rocks are classified into 3 main categories according to the origin of the materials from which they were made. ► Define compaction and cementation CLASTIC(DETRITAL) ROCKS ►A sedimentary rock formed from fragments of preexisting rocks. ► Example: Sandstone ► Size of particles: ► * Boulder = 256mm+ ► * Cobble = 64-255mm ► * Pebble = 2-64mm ► * Sand = .07-2mm ► * Clay and Mud = .06mm EXAMPLES: Sandstone Conglomerate Shale Breccia ORGANIC ROCKS ► Sedimentary rock formed either directly or indirectly from material that was once alive. ► Examples : Coal ► Some limestone comes from shells of sea animals. CHEMICAL ROCKS ►A non- clastic sedimentary rock formed by inorganic processes such as evaporation. ► The particles are too small to see. ► Examples: Limestones (caves) ► Rock Salt (Halite) Sedimentary rock features ► Stratification-layering of sedimentary rock. (beds) ► Cross-beds- slanting layers ► Graded bedding- different sizes and shapes of sediment settle to different levels. Usually, largest grains on the bottom and smallest on the top. ► Reverse grading- smallest on bottom. Large on top. ► Ripple marks- caused by action of wind and water on sand. ► Mud cracks- when muddy deposits dry and shrink. Can harden into solid rock. ► Fossils – traces of ancient plants and animals. ► Concretions- a lump of rock that has a different composition than the main body of rock. BELLRINGER ►What are the three types of sedimentary rocks? ►How does each type form? METAMORPHIC ROCKS • Meta = Change Morphic = Form • Rocks changed in form as a result of chemical reactions, heat, and/or pressure. • Examples: Gneiss, Schist, Quartzite, Marble Metamorphism • Contact metamorphism- a change in the texture, structure, or chemical composition of a rock due to contact with magma. • Regional metamorphism- a change in texture ,structure, or chemical composition of a rock due to changes in temp and pressure over a large area, generally because of tectonic force. METAMORPHIC ROCKS ARE CLASSIFIED IN TWO WAYS. Foliated • Parallel layers or bands. • 3 Basic textures – 1. Gnessic- Coarsely foliated – 2. Schistose- Finely foliated. Along which the rock splits easily. – 3. Slaty- Very finely foliated. Parallel planes of easy splitting. NON-FOLIATED (Massive) • Another metamorphic rock, not banded. • Basic Textures – 1. Granoblastic- Unfoliated or faintly foliated. – 2. Hornfelsic- Unfoliated with mineral grains that are completely microscopic; breaks sharply into angles. Metamorphic rocks • • • • • Granite= Gneiss Sandstone= Quartzite Bituminous coal= Anthracite coal Shale= Slate Limestone= Marble