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MINERALS AND ROCKS UNIT I. Atoms – Building blocks for matter Each atom on the periodic table is… Unique Identified by the mass and number of electrons Combine with other atoms in a predictable manner A Unit 2 Need to know: Atoms MAKE elements MAKE minerals MAKE rocks II. Minerals – Naturally occurring, inorganic (nonliving), homogeneous (uniform), solid materials with a definite chemical composition, molecular structure, and specific physical properties. Quartz (SiO2) There are between 2,0003,000 known Minerals on Earth. Which of the following are minerals? 1. Copper in pipes and wire 2. Table salt 5.3. 4.used Oil Sugar A Tree No, Not a mineral b/c it’s living No, Not a mineral b/c it’s living No, Not a mineral b/c it’s a liquid Yes, it’s a mineral Yes, it’s a mineral A. Mineral Formation – 1. Cooling of Magma/Lava – Liquid "rock" cools allowing various atoms to become arranged into crystalline solids. A Crystalline solid is a solid in which the atoms are arranged in a regular and repeating pattern. 2. By Evaporation – Solid deposits left after water has evaporated. Called Evaporites Important! Two minerals with the same chemical composition may have very different properties because of HOW THE ATOMS ARE ARRANGED e.g. graphite and diamonds are both made of carbon but differ greatly in their hardness. B. Crustal Composition ESRT Page 1: Composition of Earth’s Crust Oxygen is the most abundant, Silicon is the second most Although there are thousands of known minerals on Earth, most of the Earth’s crust is made of only 8 common elements (~98%). C. Mineral Composition ESRT Page 16: Properties of Common Minerals Look here… D. Mineral Groups – Based on the common elements or compounds. Some facts… the Silicates – SiO2 Largest group (made of the 2 most common elements) Based on a crystal structure called the SILICATE TETRAHEDRON Different arrangements of the Silicate Tetrahedron lead to different silicate minerals. Others… 2. the Oxides – O in common 3. the Sulfides – S in common 4. the Carbonates – CO3 in common Important: A carbonate Bubbles/Fizzes with exposed to acids including Acid Rain. Fortunately, Minerals have specific physical and chemical properties which make them identifiable. F. Physical Properties of Minerals – How do these mineral look different? 1. Color – Characteristic color of a mineral. Many minerals have more than one color. Which one is gold?? GOLD NOT A GOOD IDENTIFIER because many minerals have more than one color. Which one is Quartz? All of them 2. Hardness – A measure of how easily a mineral can be scratched. Moh’s hardness scale 3. Streak – Color of the powder of a mineral when crushed or scratched across a streak plate (unglazed porcelain). 4. Luster – How light is reflected from a minerals surface. Either metallic or non-metallic Metallic or Nonmetalic? metallic nonmetallic nonmetallic A mineral breaks by either… 5. Cleavage – Minerals that break into smooth, flat pieces. 6. Fracture – Minerals that break into jagged pieces. Minerals either have cleavage or fracture 7. Crystal Form – Characteristic shape of the mineral. Based on the arrangement of atoms. 8. Chemical and Special Properties of Minerals Many minerals possess other unique properties that add in the identification such as: taste, reaction to acids, magnetism fluorescence phosphorescence, double refraction, radioactivity, etc. Under a black light The main idea here is: All properties of minerals are based on: 1. The composition of atoms/elements 2. How the atoms are arranged Know this!!! Salt mines… F. Mineral Resources and Natural Resources – Natural, inorganic or fossilized organic materials in or on the earth’s crust that are of human use and economic value Examples: water, forests, soil, gold, coal, oil, etc. Where do minerals come from? Below ground mining Open pit mining Steel Making Virtual Cement Plant Tour | Portland Cement Association (PCA) Conservation of Minerals and Natural Resources As the human population on Earth continues to increase at it rapid rate, the availability of mineral and natural resources will decrease What can be done about that? Remember the 4 R’s – REDUCE, REUSE, RECYCLE, RECLAIM YouTube - Computer Recycling Renewable vs. Nonrenewable resources Resources that are being consumed in amounts greater than they can be replenished are nonrenewable. III. Rocks - Made of minerals. How are rocks and minerals different? They can be either: 1. Mono-Mineralic – Composed of only one mineral. 2. Poly-Mineralic – Composed of two or more minerals. (i.e. granite) calcite Three types exist: Igneous Sedimentary Metamorphic Rocks are distinguished from one another based on their origin. ESRT Page 6 - Rock cycle in Earth’s crust B. Igneous rocks (ignis=greek for fire) 1. Formation – From the cooling, solidification, crystallization of magma or lava. What is the difference between lava and magma? Igneous rocks make up 95% of Earth’s rocks Insert Picture Here Why no picture of magma? 2. Classification –Based on CRYSTAL SIZE and COLOR. a. Crystal Size is determined by the cooling environment. Outside the Earth Inside the Earth i. Intrusive – Form BELOW the Earth’s surface – Plutonic Igneous Rocks Texture – Large mineral grains that are visible to the naked eye. Nice to Know: Phaneritic Texture Formation – From MAGMA that cools slowly Examples: granite and gabbro ii. Extrusive – Form ABOVE the Earth’s surface – Called Volcanic Igneous Rocks Texture – Small mineral grains that ARE NOT visible. Nice to know: Aphanatic Texture. Formation – Form from LAVA that cools rapidly Examples rhyolite and basalt Which diagram below shows the igneous rock that cooled the fastest? Which diagram shows the igneous rock that cooled the slowest? b. Color – Determined by the Mineral Composition i. Felsic – Light-colored igneous rocks usually rich in feldspar (fel-) and silica (sic). Quartz is usually present. ii. Mafic – Dark-colored igneous rocks usually rich in magnesium (ma-) and iron (-Fe). Amphibole and pyroxene usually present. Bowen’s reaction series provides a Model for Igneous rock formation and explains how rocks can contain different minerals. 1100° C 1100°C 560°C 1. Name the 2 minerals that crystallize first (highest temperatures) 2. What is the last mineral to crystallize? 3. Why is quartz composed only of Silicon and Oxygen? 4. What elements remain in the “soup” after biotite forms? (hint: last page of ESRT’s) 2. Reading the ESRT’S - Page 6 - Scheme for Igneous Rock Identification Look at GRANITE: First, moving horizontally to the right, over to the column labeled as “texture”, you can see that it is coarse grained. Next, moving vertically down, you can see that it is light in color, low in density, and considered felsic. What minerals can(plutonic) be foundorinextrusive granite?(volcanic)? Is granite intrusive Do now – page 14 in your notes Try these: 1. What extrusive igneous rock has a fine texture and is dark in color? 2. What coarse-grained igneous rock has a mineral composition over 75% pyroxene? 3. What volcanic igneous has contains about 50% potassium feldspar and about 35% quartz? 4. What volcanic igneous rock has a glassy texture and has quartz present in its mineral composition? Going further… It is known that granite is usually found on continents and basalt is found on the ocean floor. Why do you think this so? (Hint: think of the main earlier this year – that D word) Where we are going today B. Sedimentary Rocks – Rocks made from the remains of other rocks, organic life forms (biological) or chemically dissolved materials that, over time, get changed into rock. Make up approximately 75% of the rocks on the SURFACE of the Earth. 1. Formation – Sedimentary rocks may be formed by either Compression/Cementing or evaporation. a. Compression and Cementing – Inorganic sediments or organic remains that have been transported (eroded), deposited into piles (buried), then change into rock. Erosion generally leads to rounded sediments Deposition generally occurs in large bodies of water I. Compression/Compaction – As sediments or organic remains pile up, the underlying layers become compressed II. Cementation – Natural glues hold sediments or organic remains together Natural cements may include silica, iron, lime, and/or clay. Virtual Cement Plant Tour | Portland Cement Association (PCA) b. Evaporation – Sedimentary rocks that form from minerals that are dissolved in water where the water evaporates away leaving behind the minerals. This process is also called precipitation These are called EVAPORITES and are referred to as the Crystalline Sedimentary Rocks. These are usually monominerallic. 2. Classification: a. Sedimentary rocks that form by Compression and Cementing are classified as either: Clastic Sedimentary Rocks (from the Greek word for broken – klastos) – Rocks that form from inorganic sediments Conglomerate Classification based on the size of the sediment it formed from ex. Sand, Gravel, Pebbles, etc. Bioclastic Sedimentary Rocks – Rocks that form from sea shells and other organic remains. Coquina Coal Classification based on the type of organic remains they form from b. Classification of Crystalline Sedimentary Rocks is based on the composition of the minerals they formed from. All Sedimentary Rocks usually have one or both of these features: 3. Stratification – Sedimentary rocks are usually layered horizontally with the bottom layered being the oldest. 4. Fossils – Because of the absence of EXTREME heat and pressure, fossils will usually only be found in Sedimentary Rocks. IMPORTANT!!! The presence of fossils also provides evidence for the environment in which the rocks formed. Seashells would indicate a marine environment whereas footprints would indicate a land environment. . C. Metamorphic rocks – CHANGED ROCKS (meta=change, morph=form) 1. Formation – Form when sedimentary, igneous, or even metamorphic rocks are exposed to conditions of extreme HEAT and PRESSURE. These conditions are found deep within Earth The original rock from which a metamorphic rock forms is called the PARENT ROCK. Metamorphic Rocks sometimes indicate the collision zone between two tectonic plates. Ex. The Himalayas Features of a Metamorphic Rock May include: Distorted layers Continued or new mineral growth Alignment of minerals Separation of minerals Metamorphic rocks are commonly identified by BANDING AND DISTORTION 2. Classification a. Foliated – An alignment of minerals or the separation of minerals into platy (flaky) layers or light and dark bands. Examples: 1). Slate – Was shale 2). Gneiss –Was granite 3). Schist – Was granite Because slate shows the least amount of change, it has undergone only moderate metamorphism (low-grade). b. Non-Foliated – No noticeable alignment or banding of minerals. Examples 1) Marble – Was limestone Non-foliated rocks can be identified by their crystalline appearance 3. Types of Metamorphism a. Regional Metamorphism – Occur deep within the Earth and across large areas. Usually associated with an orogeny (mountain building). b. Contact Metamorphism – BAKED ROCKS Form where a parent rock is near or in contact with an igneous intrusion – usually confined to small areas. A variation to this occurs when the metamorphism is done by extremely hot water – THERMAL METAMORPHISM YouTube - Old Faithful Geyser The AVERAGE interval between Old Faithful's eruptions is 90 minutes. The range between eruptions is from 35 minutes to 2 hours. An eruption can last from 1.5 - 5 minutes and can spray as high as 90 to 184 feet. What metamorphic would form at E? A do now… Try these from page 21 in your notes: 1. What type of metamorphism do all foliated metamorphic rocks undergo? 2. What is the parent rock for a quartzite? 3. What type of metamorphic rocks are being formed where the Himalayas are? What is the origin of the rocks pictured to the right? 4 teams enter a marathon (42 km) – The green team, red team, blue team, and white team. The team statistics are below: Green team: 5 runners who trained for a 5 km race Red team: 10 runners who trained for 5 km and 10 km races Blue team: 15 runners who trained for 5 km, 10, km, and 21 km White team: 20 runners who trained for 5 km, 10 km, 21 km, and 42 km races. A 5 km, who is dropping out of the marathon? At 18 km, who is running the race? why