EARTHSCI - Rocks and Minerals 3.pdf

CDADeLeon_EarthSci_Rocks and Minerals 1  A naturally-occurring, inorganic solid with a definite chemical Minerals composition, and an ordered internal structure. Inorganic Solid = made up of elements with no...

CDADeLeon_EarthSci_Rocks and Minerals 1  A naturally-occurring, inorganic solid with a definite chemical Minerals composition, and an ordered internal structure. Inorganic Solid = made up of elements with no Ordered Internal hydrocarbons Definite Chemical Structure = atoms are Composition = made arranged in a up of the same crystalline manner chemical compound Naturally occurring = found CDADeLeon_EarthSci_Rocks as earth material and Minerals 2 Minerals Minerals may be composed of a single element, like gold (Au) or a combination of elements. Minerals composed of more than one element are bound together by electrical bonding. All minerals formed by more than one element are therefore bound together by positive and negative ions. Example - the most abundant ions in minerals are the positively charged silicon (Si) and negatively charged oxygen (O). CDADeLeon_EarthSci_Rocks and Minerals 3 How Minerals are Formed ? 1. CRYSTALLIZATION FROM MAGMA- Magma is molten rock from deep in the Earth. As it cools, it forms minerals. 2. PRECIPITATION- Substances dissolved in water may react to form minerals. 3. CHANGES IN TEMPERATURE AND PRESSURE can make new minerals form. 4. FORMATION FROM HYDROTHERMAL SOLUTIONS. When hot solutions touch existing minerals, chemical reactions take place and form new minerals. CDADeLeon_EarthSci_Rocks and Minerals 4 Mineral Groups 1. Silicates - contains silicon-oxide (SiO4) that are the common rock-forming minerals CDADeLeon_EarthSci_Rocks and Minerals 5  Mineral Groups 2. Oxides - contains metal cations bonded 3. Sulfides - contains metal cations bonded to to oxygen sulfide that are the found in common ore minerals CDADeLeon_EarthSci_Rocks and Minerals 6  Mineral Groups 4. Sulfates - contains metal cations bonded 5. Halides - contains halogen ion (F or Cl) to sulfate anions (SO4) that are the halide salts. CDADeLeon_EarthSci_Rocks and Minerals 7  Mineral Groups 6. Carbonates - contains carbonic ions 7. Native Metals - contains single metal (CO3) and bonds to Calcium or Magnesium elements. CDADeLeon_EarthSci_Rocks and Minerals 8 Common Minerals 1. Silicon and oxygen combine to form a structure called the siliconoxygen tetrahedron. Silicates are made of silicon and oxygen. They are the most common group of minerals on Earth. Most silicate minerals crystallize from cooling magma. 2. Carbonates are minerals that contain the elements carbon, oxygen, and one or more other metallic elements. 3. Oxides are minerals that contain oxygen and one or more other elements, which are usually metals. CDADeLeon_EarthSci_Rocks and Minerals 9  4. Sulfates and sulfides are minerals that contain the element sulfur. 5. Halides are minerals that contain a halogen ion plus one or more other elements. 6. Native elements are minerals that only contain one element or type of atom. CDADeLeon_EarthSci_Rocks and Minerals 10 Important Mineral Families of the Crust CDADeLeon_EarthSci_Rocks and Minerals 11 Properties of Minerals 1. Luster - used to describe how light is reflected from the surface of a mineral. 2. Streak - the color of a mineral in its powdered form. CDADeLeon_EarthSci_Rocks and Minerals 12 Properties of Minerals 3. Breakage - used to describe how the mineral sample will tend to break Cleavage – minerals break evenly at Fracture – minerals tend to break unevenly parallel directions. at different directions CDADeLeon_EarthSci_Rocks and Minerals 13 Types of Cleavage Types of Fractures CDADeLeon_EarthSci_Rocks and Minerals 14 Properties of Minerals Small amounts of different elements can give the same mineral different colors. Streak is the color of a mineral in its powdered form. Luster is used to describe how light is reflected from the surface of a mineral. Crystal form is the visible expression of a mineral’s internal arrangement of atoms. CDADeLeon_EarthSci_Rocks and Minerals 15 Properties of Minerals The Mohs scale consists of 10 minerals arranged from 10 (hardest) to 1 (softest). Hardness is a measure of the resistance of a mineral to being scratched. You can test hardness by rubbing a mineral against another mineral of known hardness. One will scratch the other, unless they have the same hardness. CDADeLeon_EarthSci_Rocks and Minerals 16  Cleavage is the tendency of a mineral to cleave, or break, along flat, even surfaces. Minerals may have cleavage in one or more directions. Minerals that do not show cleavage when broken are said to fracture. Fracture is the uneven breakage of a mineral. Density is a property of all matter that is the ratio of an object’s mass to its volume. Some minerals can be recognized by other distinctive properties. CDADeLeon_EarthSci_Rocks and Minerals 17 Properties of Minerals 4. Hardness - is a measure of the resistance of a mineral to being scratched. CDADeLeon_EarthSci_Rocks and Minerals 18 Formation of Rocks Rocks are formed from aggregates of minerals or solid materials (e.g., natural glass or organic materials) CDADeLeon_EarthSci_Rocks and Minerals 19 Rock-Forming Elements CDADeLeon_EarthSci_Rocks and Minerals 20 Types of Rocks CDADeLeon_EarthSci_Rocks and Minerals 21  Igneous Rocks The rock cycle represents the alteration of rock- forming minerals above and below the Earth's surface. A molten rock material, magma, cools (crystallization) to form igneous rocks. If magma is extruded onto the surface it is called lava. Cooling above the surface yields rocks with fine textures, while those that form from slow cooling beneath the surface typically have large crystals. CDADeLeon_EarthSci_Rocks and Minerals 22 Igneous Rocks Igneous rock may remelt when exposed intense heat to form magma again, or be changed into metamorphic rock. Igneous rocks may also be exposed to weathering, erosion and deposition to form sediment, fragments of weathered rock and the precursor for sedimentary rock. CDADeLeon_EarthSci_Rocks and Minerals 23 Cooling of the magma initiates the crystallization of elements contained within the molten rock. The rate of cooling determines the degree to which crystals can grow. Those that form by slow cooling have large crystals and are described as being coarse-grained. Fine-gained igneous rocks form by more rapidly cooling when the molten material is exposed at the surface. As a result, crystals don't have a chance to grow very large. CDADeLeon_EarthSci_Rocks and Minerals 24 Intrusive Igneous Rock When magma intrudes into pre-existing rock it cools rather slowly because the surrounding host or country rock, as it is called, insulates the magma. As a result, crystals grow larger giving the rock mass a coarse texture. Such intrusive igneous, or plutonic rocks where the mineral grains are easily seen with the unaided eye are called porphyritic. CDADeLeon_EarthSci_Rocks and Minerals 25 Extrusive Igneous Rocks Rock Fine-grained rocks form if molten rock cools rapidly when it is extruded onto the surface. Basalt is a common extrusive igneous rock. Some fine grained rocks forming at the edge of a lava flow have small holes or vesicles which are void spaces left by escaping gasses. Very rapid cooling can produce rocks with a glassy texture such as obsidian. CDADeLeon_EarthSci_Rocks and Minerals 26 Igneous Rocks Igneous Rocks are formed from the cooling of magma. CDADeLeon_EarthSci_Rocks and Minerals 27 CDADeLeon_EarthSci_Rocks and Minerals 28 CDADeLeon_EarthSci_Rocks and Minerals 29  Sedimentary Rocks are formed when sediments Sedimentary Rocks undergo compaction and cementation Chemical Sedimentary Rocks Organic Sedimentary Rocks – Clastics Sedimentary Rocks – made up of compacted – made up of compacted made up of compacted biogenic materials chemical materials broken rocks CDADeLeon_EarthSci_Rocks and Minerals 30  Sedimentary Rock As sediments accumulate they are subjected to compaction and cementation to form sedimentary rock. Sedimentary rocks may be broken down by weathering and erosion to be deposited as sediment, exposed to intense heat and melting to return to magma, or be changed into a metamorphic rock. CDADeLeon_EarthSci_Rocks and Minerals 31  Sedimentary rocks are those formed from the compaction and cementation of fragments of pre-existing rocks called CLASTS, or plant and animals remains. The exogenic processes of weathering and erosion create the raw materials for sedimentary rocks. Earth material is loosened and moved from higher to lower elevations where it is deposited as transportation agents like water, wind or gravity lose their energy to move sediment. Streams and rivers transport sediment to lakes or oceans, or deposits it on nearby floodplains where it accumulates. CDADeLeon_EarthSci_Rocks and Minerals 32  Sedimentary Rock Process 1. Erosion involves weathering and the removal of rock. When an agent of erosion—water, wind, ice, or gravity— loses energy, it drops the sediments. This process is called deposition. Sediments form when solids settle out of a fluid, such as water or air. 2. Compaction and cementation change sediments into sedimentary rock. Compaction is a process that squeezes, or compacts, sediments. Cementation takes place when dissolved minerals are deposited in the tiny spaces among the sediments. CDADeLeon_EarthSci_Rocks and Minerals 33  The many unique features of sedimentary rocks are clues to how, when, and where the rocks formed. The oldest layers in sedimentary rock formations are at the bottom. Fossils are found in sedimentary rocks and can provide much information about the rocks that contain them. CDADeLeon_EarthSci_Rocks and Minerals 34 CDADeLeon_EarthSci_Rocks and Minerals 35 CDADeLeon_EarthSci_Rocks and Minerals 36 CDADeLeon_EarthSci_Rocks and Minerals 37 CDADeLeon_EarthSci_Rocks and Minerals 38  Metamorphic Rocks are formed when rocks undergo Metamorphic Rocks heat and pressure Foliated Metamorphic Rocks Non-Foliated Metamorphic Rocks - Has a banded or layered - Does not have a banded texture appearance CDADeLeon_EarthSci_Rocks and Minerals 39 CDADeLeon_EarthSci_Rocks and Minerals 40  Metamorphic rocks Metamorphic rocks are those that have been altered by exposure to heat and/or pressure. The pressure can be created by the weight of material lying above them. The collision of lithospheric plates creates pressure and heat that alters rock. If entirely melted, the rock material forms magma. Erosion and weathering breaks down metamorphic rocks to form sediment, which can be compacted into sedimentary rock. CDADeLeon_EarthSci_Rocks and Minerals 41 Metamorphic Rocks Metamorphism A solid-state process that transforms minerals into more stable forms Agents of Metamorphism Heat Pressure Chemically-active fluids From: http://www.windows2universe.org/earth/geology/images/temp_pr essure.gif  Effects of the different metamorphic agents Heat Promotes the growth of minerals Pressure Reduces minerals to more compact forms Deforms the original proportions of the rocks Chemically-active fluids From: Varies depending on the http://www.msnucleus.org/membership/html/jh/earth/metamorphic/imag es/rxcycle01.gif nature of the fluid Foliation Round grains can become flattened Sheet silicate minerals can have a preferred orientation  Textures of metamorphic rocks 1. Foliated – exhibits a pervasive planar structure known as foliation which is due to the nearly parallel alignment of minerals and/or compositional and mineralogical layering in the rock 2. Non-foliated – no preferred mineral orientations; metamorphism leads to transformation of one mineral to another Foliation Foliated rocks Non-foliated rocks CDADeLeon_EarthSci_Rocks and Minerals 49 CDADeLeon_EarthSci_Rocks and Minerals 50 Types of Rocks CDADeLeon_EarthSci_Rocks and Minerals 51  Types of Rocks CDADeLeon_EarthSci_Rocks and Minerals 52 The Rock Cycle Video CDADeLeon_EarthSci_Rocks and Minerals 53  Rock Cycle CDADeLeon_EarthSci_Rocks and Minerals 54  Igneous Rocks = formed Processes in the from the cooling of Magma Rock Cycle Sediments = small fragments formed from weathering of rocks Magma = formed when rocks become molten Sedimentary Rocks = Metamorphic Rocks = formed from compaction formed when rocks and cementation of undergo heat and pressure sediments CDADeLeon_EarthSci_Rocks and Minerals 55 CDADeLeon_EarthSci_Rocks and Minerals 56  Rock Cycle 1. When magma cools and hardens beneath the surface or as the result of a volcanic eruption, igneous rock forms. 2. Eventually, sediment is compacted and cemented to form sedimentary rock. Sedimentary rocks buried deep within Earth’s surface are subjected to great pressure and high temperatures. 3. Under extreme pressure and temperature conditions, sedimentary rock will change in metamorphic rock. CDADeLeon_EarthSci_Rocks and Minerals 57  Processes driven by heat from Earth’s interior are responsible for forming both igneous and metamorphic rocks. Weathering and the movement of weathered materials are external processes powered by energy from the sun and by gravity. Processes on and near Earth’s surface produce sedimentary rocks. CDADeLeon_EarthSci_Rocks and Minerals 58 CDADeLeon_EarthSci_Rocks and Minerals 59 Earth’s Mineral Resources  A renewable resource can be replenished over fairly short time spans such as months, years, or decades. By contrast, a nonrenewable resource takes millions of years to form and accumulate.  Population growth and a higher standard of living are depleting existing resources. Fossil fuels include coal, oil, and natural gas. A fossil fuel is any hydrocarbon used as a source of energy. Some energy experts believe that fuels derived from tar sands and oil shales could become good substitutes for dwindling petroleum supplies. Mining tar sand has significant environmental drawbacks. Oil shale has less heat energy than crude oil and is costly to process. Tar sand Oil Shale Gold  Some of the most important mineral deposits form through igneous processes and from hydrothermal solutions. Ore is a useful metallic mineral that can be mined at a profit. Gold, silver, copper, mercury, lead, platinum, and nickel are examples of metallic minerals produced by igneous processes. Most hydrothermal deposits are formed by hot, metal- rich fluids left by magma. Placer deposits are formed when eroded heavy minerals settle quickly from moving water.  Metallic Mineral Resources Metals that are hard and conduct electricity and heat with characteristics of lustre or shine Silver, Chromium Tin,Nickel Copper ,Iron, Lead ,Aluminium Gold Zince  Non Metallic Mineral NONMETALLIC MINERAL RESOURCES are extracted and processed either for the nonmetallic elements they contain or for their physical and chemical properties. NONMETALLIC MINERAL RESOURCES are useful for building materials, industrial minerals, and manufacturing chemicals and fertilizers.  NON METALLIC MINERAL RESOURCES Limestone for cement Marble , Asphalt , Salt, Sulfur , Asbestos Guano, Gypsum Phosphate , Silica NON METALLIC MINERAL RESOURCES  Coal Coal is a sedimentary deposit composed predominantly of carbon that is readily combustible Coal is a black or brownish black with a high amount of carbon and hydrocarbons Coal takes millions of years to form  Petroleum /Crude oil Is a naturally occurring liquid found beneath the earth’s surface that can be refined into fuel. A fossil fuel created by the decomposition of organic matter over time and used as fuel to power vehicles, heating units , and machines  Natural Gas Called FOSSIL GAS or METHANE GAS consisting of methane (95%) A fossil fuel formed when layers of organic matter ( primarily marine microorganisms) decompose under anaerobic conditions and are subjected to intense heat and pressure underground over millions of years By products of processed natural gas include ethane, propane,butane , pentanes