MODULE II Earth Science PDF

Earth Science Governor Pack Road, Baguio City, Philippines 2600 Tel. Nos.: (+6374) 442-3316, 442-8220; 444-2786; Science, Technology, Engineering and, 442-2...

Earth Science Governor Pack Road, Baguio City, Philippines 2600 Tel. Nos.: (+6374) 442-3316, 442-8220; 444-2786; Science, Technology, Engineering and, 442-2564; 442-8219; 442-8256; Fax No.: 442-6268 Email: [email protected]; Website: www.uc-bcf.edu.ph Mathematics MODULE II GRADE 11 Outline: 1. Minerals a. Mineral Properties b. Mineral Groups 2. Rocks a. Rock Classification b. Rock Cycle Learning Objectives: After completing the module, the students should be able to:  demonstrate understanding about physical and chemical properties of minerals and will be able to identify certain minerals using specific tests;  identify some common rock-forming minerals;  identify and describe the three basic rock types;  establish relationships between rock types and their mode of origin and environments of deposition/formation; and  understand the different geologic processes involved in rock formation. MINERALS AND ROCKS Mineral is a naturally occurring (not man-made or machine generated), inorganic (not a by- product of living things), solid with an orderly crystalline structure and a definite chemical composition. Minerals are the basic building blocks of rocks such as salt (halite), graphite, diamond, and gold. MINERAL PROPERTIES 1. Luster - It is the quality and intensity of reflected light exhibited by the mineral. a. Metallic – generally opaque and exhibit a resplendent shine similar to a polished metal b. Non-metallic – vitreous (glassy), adamantine (brilliant/diamond-like), resinous, silky, pearly,dull (earthy), greasy, among others. 2. Hardness - It is a measure of the resistance of a mineral to abrasion. The Mohs Scale of Hardness Friedrich Mohs in 1812 measures the scratch resistance of various minerals from a scale of 1 to 10, based on the ability of a harder material/mineral to scratch a softer one. Figure 1.Mohs Scale of Hardness Source: http://www.instructables.com/id/How-to-identify-a-Mineral/step3/Hardness/ (8/30/2015)  Earth Science Governor Pack Road, Baguio City, Philippines 2600 Tel. Nos.: (+6374) 442-3316, 442-8220; 444-2786; Science, Technology, Engineering and, 442-2564; 442-8219; 442-8256; Fax No.: 442-6268 Email: [email protected]; Website: www.uc-bcf.edu.ph Mathematics MODULE II GRADE 11 3. Color and streak a. Color maybe a unique identifying property of certain minerals. A lot of minerals can exhibit same or similar colors. Individual minerals can also display a variety of colors resulting from impurities and also from some geologic processes like weathering. Examples of coloring: quartz can be pink (rose quartz), purple (amethyst), orange (citrine), white (colorless quartz) b. Streak on the other hand, is the mineral’s color in powdered form. It is inherent in almost every mineral, and is a more diagnostic property compared to color. Note that the color of a mineral can be different from its streak. Examples of streak: 1. Pyrite (FeS2) exhibits gold color but has a black or dark gray streak. 2. Hematite (Fe2O3). Figure 1.Color vs streak of a hematite (Fe2O3). Source: http://www.instructables.com/id/How-to-identify-a-Mineral/step6/Streak/ (8/30/2015) 4. Crystal Form/Habit ◦ The form reflects the supposedly internal structure (of atoms and ions) of the crystal (mineral). It is the natural shape of the mineral before the development of any cleavage or fracture. The crystal forms also define the relative growth of the crystal in 3 dimension which are its length, width and height. Examples : prismatic, tabular, bladed, platy, reniform and equant. ◦ A mineral that do not have a crystal structure is described as amorphous. Figure 2.Crystal form / habit. Source: http://www.slideshare.net/davidprestidge/earth-lecture-slide-chapterfive page 46 of 74 (8/30/2015) 5. Cleavage – the property of some minerals to break along specific planes of weakness to form smooth, flat surfaces. ◦ Cleavage is the weak plane that developed after the crystal is formed. These planes exist because the bonding of atoms making up the mineral happens to be weak in those areas. ◦ Cleavage is different from habit; the two are distinct, unrelated properties. Although both are dictated by crystal structure, a crystal habit form as the mineral is growing, relying on how the individual atoms in the crystal come together.  Earth Science Governor Pack Road, Baguio City, Philippines 2600 Tel. Nos.: (+6374) 442-3316, 442-8220; 444-2786; Science, Technology, Engineering and, 442-2564; 442-8219; 442-8256; Fax No.: 442-6268 Email: [email protected]; Website: www.uc-bcf.edu.ph Mathematics MODULE II GRADE 11 6. Fracture - Some minerals may not have cleavages but exhibit broken surfaces that are irregular and non-planar. Quartz for example has an inherent weakness in the crystal structure that is not planar. Examples of fracture are conchoidal, fibrous, hackly, and uneven among others. 7. Specific Gravity - The ratio of the density of the mineral and the density of water - This parameter indicates how ma ny times more the mineral weighs compared to an equal amount of water (SG 1). For example, a bucket of silver (SG 10) would weigh ten times more than a bucket of water. 8. Others - There are certain unique properties of minerals that actually help in their identification (e.g. magnetism, odor, taste, tenacity, reaction to acid, etc.). Magnetite is strongly magnetic; sulfur has distinctive smell; halite is salty; calcite fizzes with acid as with dolomite but in powdered form. Example: magnetite is strongly magnetic sulfur has distinctive smell halite is salty calcite fizzes with acid MINERAL GROUPS The most stable and least ambiguous basis for classification of minerals is based on their chemical compositions. Figure 3. Mineral Groups 1. Silicates ◦ Are minerals containing the two most abundant elements in the Earth’s crust, namely, silicon and oxygen. When linked together, these two elements form the silicon oxygen tetrahedron – the fundamental building block of silicate minerals. ◦ Over 90% of rock-forming minerals belong to this group. ◦ Aside from Si (46.6 % by wt.) and O (27.7%), the other most common elements that make the earth’s crust are Al (8.1), Fe (5.0), Ca (3.6), Mg (3.1), Na (2.8) and K 2.6). Ex. olivine, quartz 2. Oxides - They are minerals composed of oxygen anion (O2-) combined with one or more metal ions. Ex. magnetite, hematite 2. Sulfates - Sulfates are minerals containing sulfur and oxygen in the form of the (SO4)- anion. Ex. Gypsum  Earth Science Governor Pack Road, Baguio City, Philippines 2600 Tel. Nos.: (+6374) 442-3316, 442-8220; 444-2786; Science, Technology, Engineering and, 442-2564; 442-8219; 442-8256; Fax No.: 442-6268 Email: [email protected]; Website: www.uc-bcf.edu.ph Mathematics MODULE II GRADE 11 3. Sulfides - Are minerals containing sulfur and a metal; some sulfides are sources of economically important metals such as copper, lead, and zinc. 4. Carbonates - Carbonates are minerals containing the carbonate (CO3)2- anion combined with other elements 5. Native Elements - Are minerals that form as individual elements. a. Metals and Inter-metals – minerals with high thermal and electrical conductivity, typically with metallic luster, low hardness EX. (gold, lead, copper) b. Semi-metals – minerals that are more fragile than metals and have lower conductivity. Ex. (arsenic, bismuth) c. Nonmetals – nonconductive Ex. (sulfur, diamond) 7. Halides - Halides are minerals containing halogen elements combined with one or more metals. ROCKS CLASSIFICATION Rocks are natural substances consisting of aggregate minerals clumped together with other minerals through natural processes. They are like other minerals are a product of a natural cyclic process. TYPES OF ROCKS 1. Igneous Rocks - Rocks that are formed from the solidification of molten rock material (magma or lava). - Magma is a molten rock material beneath the surface of the earth while lava is a molten rock material extruded to the surface of the earth through volcanic or fissure eruptions. - Molten rock material can solidify : a.below the surface of the earth (plutonic igneous rocks/intrusive ignoeus rocks) or b.at the surface of the Earth (volcanic igneous rocks/extrusive igneous rocks). - Minerals are formed during the crystallization of the magma. - Note that the rate of cooling is one of the most important factors that control crystal size and the texture of the rock in general. Figure 4. Lava and Magma 2. Sedimentary - These are rocks that formed through the accumulation, compaction, Rocks and cementation of sediments. - They generally form at surface or near surface conditions. - Sedimentary processes at or near the surface of the Earth include: 1. weathering of rocks, 2. sediment transport and deposition, 3. Compaction, and 4. Cementation  Earth Science Governor Pack Road, Baguio City, Philippines 2600 Tel. Nos.: (+6374) 442-3316, 442-8220; 444-2786; Science, Technology, Engineering and, 442-2564; 442-8219; 442-8256; Fax No.: 442-6268 Email: [email protected]; Website: www.uc-bcf.edu.ph Mathematics MODULE II GRADE 11 - Factors in sedimentary processes: weathering and transport agents (water, wind ice). - Fossils: remains and traces of plants and animals that are preserved in rocks Two Types: 1. Non-clastic / Chemical/Biochemical evaporation and precipitation from solution or lithification of organic matter. They are classified as evaporites (halite, gypsum and dolostone), precipitates (limestone) and bioclastics (coal, coquina).The chart below summarizes the features of the non-clastic rocks. Figure 5. Non-clastic rocks 2. Clastic/terrigenous - grains, matrix and cement are the components of clastic rocks.Clastic rocks are commonly classified based on particle size. - Clastic rocks with volcanic origin (e.g. pyroclastics) and may have undergone some stages in the sedimentary processes could be classified as sedimentary rock (e.g. volcanoclastic rocks). - The presence of variable grain sizes (including matrix and cement) is indicative of sedimentary differentiation which is actually a function of processes happening in different sedimentary environments. - Table below shows the different clastic rocks. Figure 6. Clastic Rocks  Earth Science Governor Pack Road, Baguio City, Philippines 2600 Tel. Nos.: (+6374) 442-3316, 442-8220; 444-2786; Science, Technology, Engineering and, 442-2564; 442-8219; 442-8256; Fax No.: 442-6268 Email: [email protected]; Website: www.uc-bcf.edu.ph Mathematics MODULE II GRADE 11 3. Metamorphic - Are rocks that form from the transformation of pre-existing rocks Rocks (igneous, sedimentary, or metamorphic rocks) through the process of metamorphism. - Metamorphism can involve changes in the physical and chemical properties of rocks in response to heat, pressure, and chemically active fluids. - They are commonly formed underneath the earth through metamorphism Two Kinds 1.Contact metamorphism ◦ Heat as the main factor: occurs when a pre-existing rocks get in contact with a heat source (magma) ◦ Occurs on a relatively small scale: around the vicinity of intruding magma ◦ Creates non-foliated (crystals arranged in random manner) metamorphic rocks (e.g. hornfels) 2.Regional metamorphism ◦ Pressure as main factor: occurs in areas that have undergone deformation during orogenic event resulting in mountain belts ◦ Occurs in a regional/large scale ◦ Creates foliated (crystals aligned in layers) metamorphic rocks such as schist and gneiss ◦ Non-foliated rocks like marble also form thru regional metamorphism, where pressure is not intense, far from the main geologic event. ◦ Below is a table of the different common metamorphic rocks. Figure 7. Different Common Metamorphic rocks  Earth Science Governor Pack Road, Baguio City, Philippines 2600 Tel. Nos.: (+6374) 442-3316, 442-8220; 444-2786; Science, Technology, Engineering and, 442-2564; 442-8219; 442-8256; Fax No.: 442-6268 Email: [email protected]; Website: www.uc-bcf.edu.ph Mathematics MODULE II GRADE 11 THE ROCK CYCLE - Rock cycle is a model that describes all the processes by which rocks are formed, modified, transported, decomposed, melted and reformed. - It is also defined as constant recycling of minerals and it illustrates how geologic processes occurring both underneath and on the Earth’s surface that changes a rock from one type to another. Figure 9.The Rock Cycle Source: http://rockcycle8.wikispaces.com/rock+cycle Reference Material/s: Leopoldo de Silva, Ph.D. (2016)Teaching Guide for Senior High School Earth Science, Commission on Higher Education,C.P. Garcia Ave., Diliman, Quezon City Gheoeiochta, S(2020) Geological Survey: The Rock Cycle.Ireland.Retreived from: http://rockcycle8.wikispaces.com/rock+cycle