Chapter 2 School Of Rocks PDF

CHAPTER 2 SCHOOL OF MARJORIE P. JOMOC, LPT ROCKS  LESSONS The Rock and Rock-Forming 01 Rock Cycle 02 Minerals Endogenic 03 Exogenic Process 04 Processes...

CHAPTER 2 SCHOOL OF MARJORIE P. JOMOC, LPT ROCKS  LESSONS The Rock and Rock-Forming 01 Rock Cycle 02 Minerals Endogenic 03 Exogenic Process 04 Processes 05 Plate Motion  1 The Rocks & Rock Cycle  LESSON OBJECTIVES ❑ Identify the common rock-forming minerals using their physical and chemical properties. ❑ Classify rocks into igneous, sedimentary, and metamorphic.  WHAT IS ROCK? ❑A rock is a naturally- occurring, coherent aggregate of minerals such as natural glass or organic matter. ❑ Rocks are found in the lithosphere, which is derived from the Greek word lithos which means “stone”.  WHAT IS ROCK CYCLE? ❑ The rock cycle is a model that describes all the processes by which rocks are formed, modified, transported, decomposed, melted and reformed. ❑ These processes occur both on Earth`s surface and underneath.  IGNEOUS ROCKS ❑ Igneous Rocks are formed through the cooling of magma or lava. ❑ The term “igneous” is based from the Latin ignis, which means “fire”. ❑ It forms at much higher temperatures.  IGNEOUS ROCKS ❑ Below the surface, from slowly cooling magma; DIORITE rocks formed have good crystallization (coarse- GRANITE grained); may become plutonic rocks or intrusive igneous rocks. SYENITE  IGNEOUS ROCKS ❑ On the surface, from rapidly or fast- cooling ANDESITE lava; rocks formed have no visible crystals (fine- grained); may become BASALT volcanic rocks or extrusive igneous. RHYOLITE  IGNEOUS ROCKS ❑ On the surface, from ❑ The formation of the consolidation of pyroclastic rocks is a particles erupted by hybrid of igneous and explosive volcanic sedimentary activity; may become processes. pyroclastic igneous rocks like ignimbrite, scoria, pumice, tuff and volcanic breccia.  IGNIMBRITE SCORIA PUMICE EXAMPLES  SEDIMENTARY ROCKS ❑ Sedimentary Rocks are the ❑ The term was derived from products of the lithification of Latin sedentarius, which particles produced by the means “sitting”, as these weathering and erosion of sediments will eventually be other preexisting rocks. deposited and remain until ❑ Aside from rock particles, they are transformed into they may also be comprised of sedimentary rocks. mineral fragments and organic ❑ It forms at much lower material known as “sediments”. temperature than igneous rocks. EXAMPLES  SEDIMENTARY ROCKS ❑ From the cementation of sediments that have been deposited, buried, and SANDSTONE compacted over a long period of time, this type of SHALE rock called clastic, can be differentiated based on the size of the sediments or clasts in the rocks. CONGLOMERATE  SEDIMENTARY ROCKS ❑ From the precipitation of ❑ Once the solution is minerals from ions in solution; saturated, the rocks that are exposed to water precipitation of and oxygen can slowly experience chemical changes minerals like calcite such as oxidation (rusting) and and halite can occur, hydrolysis through time. leading into the ❑ These processes break down formation of chemical rocks into their chemical sedimentary rocks. components -- ions.  CALCITE HALITE EXAMPLES  SEDIMENTARY ROCKS ❑ From the compaction and cementation of plant COQUINA and/or animal remains, these types of rocks are called bioclasts. ORGANIC LIMESTONE  METAMORPHIC ROCKS ❑ Metamorphic Rocks are ❑ These processes are formed when preexisting or collectively known as parent rocks (whether metamorphism which igneous, sedimentary or means “change in form”. even metamorphic) are ❑ It usually occurs altered by heat, pressure underneath the surface, and the chemical activity of although not as deep as fluids. the igneous environment.  METAMORPHIC ROCKS ❑ When the dominant factor is pressure, due to volcanic activity, ❑ The term comes from the the flat and/or elongated mineral Latin folium which means components of the preexisting “leaf” where the flat leaves rocks react by aligning are on top of each other. perpendicular to the axis of the ❑ This type of pressure. metamorphism is called ❑ It result in a layered or banded regional metamorphism. appearance in the rocks called foliation, and these types of rocks are called foliated metamorphic rocks. EXAMPLES  METAMORPHIC ROCKS ❑ When the dominant altering ❑ It results in rocks like factor is heat, usually from direct marble and quartzite that contact between an older rock are called nonfoliated material and an intruding body metamorphic rocks. of magma, the parent rocks may undergo a fundamental change in texture due to recrystallization, this process is called contact metamorphism.  QUARTZITE MARBLE EXAMPLES  CLASSIFICATION OF ROCKS TEXTURE 01 It refers to the size, shape, and arrangement of mineral grains and other constituents which are controlled by processes involved in the formation of the rock. COMPOSITION 02 The minerals composition in rocks is taken as the natural expression of composition.  Size APHANITIC ❑ Aphanitic rocks have grains that are too small to see or identify PHANERITIC ❑ Phaneritic rocks have grains which are big enough to see.  PHANERITIC ROCK APHANITIC ROCK EXAMPLES ❑ In igneous rocks, the difference between aphanitic is at grain size of 1/16 mm. a. If the grain size is larger than 1/16 mm, the rock is phaneritic. b. If the grain size is less than 1/16 mm, the rock is aphanitic ❑ In sedimentary rocks, the difference between aphanitic and phaneritic is set at 1/256 mm. ❑ In metamorphic rocks, the difference between aphanitic and phaneritic cis less quantifiable. ROCK CYCLE AS BIOGEOCHEMICAL CYCLE Rock-Forming Minerals 2  WHAT IS MINERALS? ❑ Each mineral is unique but they generally exhibit the following characteristics: a. They are naturally-occurring chemical compounds b. They are inorganic c. They are homogeneous solids d. Each mineral has a definite chemical composition e. Each mineral`s structure arranges atoms in a crystalline pattern.  EXAMPLES GRAPHITE GOLD DIAMOND COPPER  PHYSICAL PROPERTIES LUSTER COLOR ▪ It refers to the quality of light on the ▪ A mineral`s color is caused by the surface of a rock, crystal or mineral. absorption, or lack thereof, of visible ▪ A mineral with high luster is light by their crystalline structure. reflective. ▪ Most minerals have color in various ▪ It describes a mineral`s luster as hues, hence cannot be distinguished greasy, silky, metallic, earthy and by color alone. vitreous. EXAMPLES  PHYSICAL PROPERTIES STREAK HARDNESS ▪ It refers to the color of the ▪ It is the mineral`s ability to resist powdered mineral produced when it scratching or abrasion. is dragged across an unweather ▪ Hardness is determined by surface. comparing the relative hardness of ▪ Streak color is particularly useful in an unknown specimen with another distinguishing metallic and mineral with known hardness. nonmetallic minerals. EXAMPLES  MOHS SCALE OF HARDNESS INDEX MINERAL SCALE COMMON OBJECTS Diamond 10 Corundum 9 Topaz 8 Quartz 7 Steel File (6.5) Orthoclase 6 Glass (5.5) Apatite 5 Knife Blade (5.1) Fluorite 4 Wire Nail (4.5) Calcite 3 Penney (3.5) Gypsum 2 Fingernail (2.5) Talc 1 EXAMPLES  PHYSICAL PROPERTIES CLEAVAGE ▪ It is the tendency of a mineral to split, or cleave, along planes of weakness. ▪ Minerals that break easily and cleanly along one or more planes are said to have good cleavage. ▪ If the break is not define, the cleavage is classified as poor.  PHYSICAL PROPERTIES FORMULA: SPECIFIC GRAVITY Specific Gravity = ▪ It is a measure of relative density of mass of mineral a mineral. mass of equal volume ▪ It is determined by comparing its of water relative mass to water. ▪ A mineral with a specific gravity of 3.0 is three times (3x) heavier than an equal volume of water. EXAMPLES EXAMPLES THANK YOU!