1. Structure ofthe Earth

2. The Minerals Minerals are a collection of one ormore elements that are stacked neatlytogether in a form called crystalstructure. They are stable at roomtemperature, has an ordered atomicstructure and representable by achemical formula. 3. How minerals are beingformed? Minerals are formed either by highheat and high pressure existingbeneath the lithosphere or by naturalprocess like evaporation andprecipitation. Halite and gypsum areformed through evaporation. 4. General properties ofMinerals Minerals are solid. Minerals have a definite chemicalcomposition. Minerals have a definite shape. Minerals are inorganic. When minerals dissolve in liquid, itloses its crystalline property and thuscease to exist as mineral. 5. Physicalproperties ofMinerals 6. 1. Color the first thing to be noticed in amineral. Basic way of identifying mineralsare by color.Galena isblackElbaite is turquoise green.Apatite islemon yellow 7. 2. Streaks refers to the color of thepowder on a mineral when rubbed in ahard, white piece of unglazed porcelain. 8. 3. Hardness the ability of one mineral to scratchanother. The softer mineral gets scratched. Thehardest mineral is diamond and the softest is talc. 9. 4. Luster refers to the ability of minerals toreflect light.5. Cleavage is the flat surface alongwhich minerals split.This sample of fluorite shows a smoothcleavage face on the left where themineral broke along the plane of its cubiccrystal structure. 10. 6. Texture refers to how minerals feel tothe touch. 11. Classification of Minerals Silicates compounds of silicon andoxygen. Makes up 96% of the earthscrust. Carbonates compounds formed withthe carbonate group. It is the principalmineral in limestone. Calcite is the mostcommon example of a mineral whichbelong to the carbonates. Sulfates are compound formed withsulfate group. Gypsum is the mostabundant rock forming sulfate. 12. Halides compounds formed fromhalogen and sodium, potassium orcalcium. Halite is the most commonexample as it is a table salt or sodiumchloride. Oxides compounds of oxygen and otherelements. Most common are the oxides ofiron and aluminum. Hermatite is ferricoxide. Sulfides are minerals containing one ormore metals combined with sulfur. 13. Crystal Systems The crystal pattern of minerals iscontrolled by the internal arrangementof the atoms that make up the mineral.Some examples of these crystalstructures are quartz which has ahexagonal (six-sided) crystal andhalite which has a cubic crystal. 14. Crystal Systems 15. Most Common Crystals 16. Rocks Makes up the solid part of the earthscrust. Usually made up of one or moreminerals. Some are made by only onemineral. Coal is special kind of rock. 17. 3Classifications ofRocks 18. Igneous Rocks The word igneous comes from aGreek word which means fire. Oldest of all types of rocks. Contains no fossils. Rarely reacts with acid. Usually has no layering. Usually made of of two or moreminerals. May be light or dark-colored. Has glass fibers. 19. Examples of Igneous Rocks:Granite composed of quartz, feldspar, mica, andhormblende. Granite forms as magma cools farunder the earths surface. It cools very slowly.Basalt dark-colored, fine grained extrusiverock. The mineral grains are so fine that theyare impossible to distinguish with the nakedeye or even a magnifying glass.Gabbro dark-colored, coarse-grainedintrusive igneous rock. Composed mostly ofplagioclase feldspar with small amount ofpyroxene and olivine. 20. Rhyolite very closely related to granite only that ithas much finer crystals. These crystals are so smallthat they cannot be seen by the naked eye. Rhyolitecooled much more rapidly than granite giving it aglassy appearance.Pumice light-colored, frothy volcanic rock.Formed from lava that is full of gas. Duringeruption, as the lava hurtles through the air, it coolsand the gases escape leaving the rock full of holes.Obsidian very shiny natural volcanic glass.When an obsidian breaks, it fractures with adistinct conchoidal fracture. Obsidian isproduced when lava cools very quickly that nocrystals can form. 21. Two Types of Igneous rocks: Intrusive igneous rocks that coolsslowly deep beneath the earths surface.The slow cooling results to formation oflarge crystals. Granite is an example ofan intrusive igneous rock. Extrusive igneous rocks that cools veryquickly as the lava is erupted or magmareaches the surface. Obsidian and basaltare two examples of extrusive igneousrocks. They are commonly shiny andglassy. 22. Sedimentary Rocks Formed through erosion and otherweathering agents such as wind, water andice. Often contains fossils. Reacts with acid. Has layers, flat or curved. Composed of pieces cemented or pressedtogether. Has great color variety. Has pored between pieces. May have cross-bedding, mud cracks, wormburrows, raindrop impressions. 23. Examples of SedimentaryRocks: 24. Conglomerate a clastic sedimentary rock that is formed from thecementing of rounded cobble and pebble sized rock fragments.Formed by river movement or ocean wave action. Chert a very hard sedimentary rock that is commonly found innodules in limestone. Chert is dark gray to light gray in color. Itprobably formed from the remains of ancient sea sponges or otherocean animals fossilized. Limestone the most abundant of the non-clastic sedimentary rocks.Limestone is produced from the mineral calcite and sediment. Sandstone is a clastic sedimentary rock that forms from thecementing together of sand sized grains forming a solid rock. Shale - Shale, common name applied to fine-grained varieties ofsedimentary rock formed by the consolidation of beds of clay or mud.Most shales exhibit fine laminations that are parallel to the beddingplane and along which the rock breaks in an irregular, curvingfracture. Shales are usually composed of mica and clay minerals. Arkose - a coarse-grained sedimentary rock rich in feldspar andquartz. 25. Three Types of SedimentaryRock: Clastic rocks - form from clasts, orbroken fragments, of pre-existingrocks and minerals. Chemical rocks - form when mineralsprecipitate, or solidify, from a solution,usually seawater or lake water. Organic rocks - form fromaccumulations of animal and plantremains. 26. Metamorphic Rocks Comes from Greek words meaning changeand form. Formed deep in the earth where hightemperature, great pressure, and chemicalreactions cause one type of rock to changeinto another type of rock. Metamorphic rocks begin to form at 12-16kilometers beneath the earths surface. They begin changing at temperatures of 100degrees Celsius to 800 degrees Celsius. Reacts with acid. Rarely has pores or openings. May have bent or curved foliation. 27. Examples of MetamorphicRocks: 28. Marble metamorphosed limestone or dolomite. Comes inmany color (white, red, black, mottled and banded, gray, pink,and green.) Slate a fine-grained metamorphic rock with perfect cleavagethat allows it to split into thin sheets. Slate usually has a lightto dark brown color. Schist a medium grade metamorphic rock. It is moresubjected to more heat and pressure than slate, which is alow grade metamorphic rock. Gneiss a high grade metamorphic rock. It is more subjectedto heat and pressure than schist. Quartzite composed of sandstone that has beenmetamorphosed. Quartzite is much harder than the parentrock, sandstone. It forms from sandstone that has come intocontact with deeply buried magmas. 29. The Rock Cycle 30. Fossils Fossil, remains or traces of prehistoric plantsand animals, buried and preserved insedimentary rock, or trapped in organicmatter. Fossils representing most livinggroups have been discovered, as well asmany fossils representing groups that arenow extinct. Fossils range in age from 3.5-billion-year-old traces of microscopiccyanobacteria (blue-green algae) to 10,000-year-old remains of animals preserved duringthe last ice age. Paleontologists (scientistswho study prehistoric life) use fossils to learnhow life has changed and evolved throughoutearths history. 31. Body Fossils It refers to the preserved remains ofan animal or plants body. The most common body fossilsinclude bones, teeth, eggs and skin.But the skin is less dense compared tothe three mentioned body fossils andthat it is easily decomposed. 32. Trace Fossils Trace fossils are everything else thatthe dinosaurs and our ancestors leftbehind that are not part of their bodyincluding footprints, egg shells, nests,and game trails. Scientists are able to learn additionalinformation about dinosaurs fromthese traces that they cannotaccurately gain from body fossilsalone. 33. FossilizationProcesses 34. Carbonization Plants are most commonly fossilized throughcarbonization. In this process, the mobile oilsin the plants organic matter are leached outand the remaining matter is reduced to acarbon film. Plants have an inner structure ofrigid organic walls that may be preserved inthis manner, revealing the framework of theoriginal cells. Animal soft tissue has a lessrigid cellular structure and is rarely preservedthrough carbonization. Althoughpaleontologists have found the carbonizedskin of some ichthyosaurs, marine reptilesfrom the Mesozoic Era (240 to 65 millionyears before present), the microscopicstructure of the skin was not preserved. 35. When plants are preserved through carbonization, the oils in the plantgradually leach out, leaving a carbon film. The rigid walls of plant cellspreserved in this manner reveal the original cellular structure of the ancientplant. 36. Petrifaction Another common mode of preservation ofplants is petrifaction, which is thecrystallization of minerals inside cells. One ofthe best-known forms of petrifaction issilicification, a process in which silica-richfluids enter the plants cells and crystallize,making the cells appear to have turned tostone (petrified). Famous examples ofsilicification may be found in the petrifiedforests of the western United States (PetrifiedForest National Park). Petrifaction may alsooccur in animals when minerals such ascalcite, silica, or iron fill the pores and cavitiesof fossil shells or bones. 37. Replacement Replacement occurs when an organism is buried inmud and its remains are replaced by sulfide (pyrite) orphosphate (apatite) minerals. This process mayreplace soft tissue, preserving rarely seen details ofthe organisms anatomy. X-ray scanning of someGerman shales from the Devonian Period (410 millionto 360 million years before present) have revealedlimbs and antennae of trilobites (extinct ocean-dwellingarthropods) and tentacle arms of cephalopods (highlydeveloped mollusks) that have been pyritised(replaced by pyrite). Paleontologists have used mildacids to etch the phosphatized fossil remains ofancient fish found in Brazil to reveal structures such asgills and muscles. Although mineral replacement israre, fossils created in this way are important in helpingpaleontologists compare the anatomical details ofprehistoric organisms with those of living organisms. 38. Recrystallization Many animal shells are composed of themineral aragonite, a form of calciumcarbonate that breaks down over millions ofyears to form the more stable mineral calcite.This method of preservation, calledrecrystallization, destroys the microscopicdetails of the shell but does not change theoverall shape. Snail shells and bivalve shellsfrom the Jurassic Period (205 million to 138million years before present) and later are stillcomposed principally of aragonite. Most oldershells that have been preserved haverecrystallized to calcite. 39. Soft-tissue Preservation The soft tissues of animals are preserved only underextremely unusual conditions, and the preserved tissueusually lasts for only a short period of geological time. In theSiberian permafrost (earth that remains frozen year-round),for example, entire mammoths have been preserved in ice forthousands of years. The remains of the mammoths lastmeals have sometimes been preserved in the stomachs,allowing paleontologists to study the animals diet. Mummification may occur in hot, arid climates, which candehydrate organisms before their soft tissue has decayedfully. The skin itself is preserved for only a short time, but theimpressions of the skin in the surrounding sediment can bepreserved much longer if the sediment turns to rock.Paleontologists have found skin impressions of dinosaurspreserved by this method. 40. Organic Traps Whole organisms may become trapped and preserved in amber,natural asphalt, or peat (decaying organic matter). Amber is thefossilized remaining part of tree sap. When sap first flows from thetree, it is very thick and sticky, so as it runs down the trunk, it maytrap insects, spiders, and occasionally larger animals such aslizards. These organisms can be preserved for millions of years withdetails of their soft tissue, such as muscles and hair-like bristles, stillintact. Natural asphalt (also called tar) is a residue from oil that has seepedto the earths surface from deposits in the rock below. When anasphalt pit is covered by water, thirsty animals that come to the pit todrink may become trapped in the sticky substance and bepreserved. One well-known example of such an area is the La BreaTar Pits of the Pleistocene Epoch (1.6 million to 10,000 years beforepresent) in Los Angeles, California. Animals may also be preserved in peat, although the acidicenvironment of this decaying organic matter may cause bones tolose their rigidity. Some human remains have been found in peatbogs in Denmark (2000 years old) and England (2200 years old). 41. Paleontologists can learn about prehistoric life by studying the remains ofancient insects, such as this midge fly, trapped in tree resin when they werealive. The resin eventually hardens and fossilizes into amber. Occasionallywhole organisms are preserved in this manner. 42. Molds and Casts Acidic conditions may slowly dissolve awaythe skeleton of fossil animals preserved inrock, leaving a space where the organismused to be. The impression that is left in therock becomes a mold. This processcommonly occurs in fossil shells where thecalcite shell dissolves easily. The impressionof the outside of the shell is the externalmold. Sometimes the inside of the shell isfilled with sediment before the shell isdissolved, leaving an internal impression ofthe shell called an internal mold. If the spacewhere the shell used to be is then filled witha new mineral, the replica of the shell formsa cast. 43. Although trilobites became extinct about 250 million years ago, theirfossilized casts can be found in rock formations. This silica shale formationshows several trilobites. Because these primitive arthropods were typicalorganisms of the Paleozoic era, a paleontologist may use them to determinethe relative age of the rock strata. 44. Track and Trails When animals walk through softsediment such as mud, their feet, tails,and other body parts leave impressionsthat may harden and become preserved.When such an impression is filled with adifferent sediment, the impression formsa mold and the sediment that fills themold forms a cast. Molds and casts ofdinosaur tracks are relatively commonand help paleontologists understand howthese creatures moved. 45. When dinosaurs walked through soft sediments or mud, the groundoccasionally hardened quickly enough to preserve their footprints.Paleontologists use dinosaur footprints to learn about how dinosaurswalked and their patterns of movement. These prints, found in Arizona,were made by a theropod dinosaur from the Jurassic Period. Mosttheropods walked on two legs and were carnivorous. 46. Most Abundant Fossils: 47. Geologic Timeline