Geology PDF - Minerals and Properties

Geology - study of earth, geoscience, primary earth science, how earth is formed; structure, composition, types of processes RECALL: RECALL Minerals - the building blocks of rocks ★Mineral - natural, inorganic(no carbon, hydrogen bonds) , solid, it possess an orderly internal structure of...

Geology - study of earth, geoscience, primary earth science, how earth is formed; structure, composition, types of processes RECALL: RECALL Minerals - the building blocks of rocks ★Mineral - natural, inorganic(no carbon, hydrogen bonds) , solid, it possess an orderly internal structure of atoms, definite chemical composition ★Mineraloid - it has no ordered atomic structure and lacks definite chemical composition Ex. pele’s hair, libyan desert glass, tektites Classification of Minerals -they r organized according to anion (or group) ‘cause it has the biggest effect on the properties ★Silicates -silicon and oxygen combine to form a structure called silicon-oxygen tetrahedron, this structure provides the framework of every silicate mineral(ex. olivine) ☆Isolated tetrahedra - simplest silicate structure, bonded to iron/magnesium ☆Chain Silicates - single-chain, one oxygen from each tetrahedron is shared with adjacent tetrahedra(ex. pyroxenes) ☆Sheet Silicates - arranged in sheets, each tetrahedron shares three oxygen with adjacent tetrahedra, all sheet silicates have water(OH-) ☆Feldspar - group of very abundant frameworks in the earth’s crust, classified using a ternary(3-fold) system with three end-member, each end-member at one corner, distance represents the relative abundance ☆Quartz - contains only silica tetrahedra, each silica tetrahedron is bonded to four other tetrahedra, making three dimensional framework, 1 silicon : 2 oxygen, its hardness and the fact that it breaks irregularly is because of its strong covalent/ionic bonds ★Carbohydrates - contain the elements carbon, oxygen, and one or more other metallic elements ★Oxides - contain oxygen and one or more other elements(usually metals) ★Sulfates and Sulfides - contain the element sulfur ★Halides - halogen ion plus one or more other elements ★Phosphates - phosphate plus one or more other elements(this makes up the enamel of your teeth) ★Native Elements - single element, such as gold, copper, silver or sulfur Physical Properties of Minerals ★Crystal Systems 5-Orthorhombic 1-Cubic 6-Monoclinic 2-Tetragonal 3-Hexagonal 7-Triclinic 4-Trigonal(Rhombohedral) ★Luster - how a mineral’s surface reflects light, how the interior of the mineral may refract or bend light helps identify minerals ★Metallic Luster - reflectivity and brightness of metal, are always opaque, smoother surface, the brighter their luster, the higher they reflectivity, colors similar to native metals ★Non-Metallic Luster ☆Vitreous Luster - similar to glass, “glassy”, 70 % of minerals can exhibit this ☆Dull Luster - “earthy”, nonreflective, rough, porous, granular surface, scatters light instead of reflecting  ☆Greasy Luster - appears to be coated with a thin layer of oil or grease ☆Pearly Luster(nacreous) - similar to pearl, often on cleavage surface, light enters the mineral and reflects from multiple atomic planes, out of focus glow of light. ☆Resinous Luster - name refers to appearance of resin secreted by conifer trees ☆Silky Luster - many parallel fibers or parallel crystals that are bound together and reflect light ☆Waxy Luster - appearance: surface of candle, translucent, direct light upon them produces soft waxy glow ☆Adamantine Luster - highest luster, similar to vitreous, more reflective, no sharp division between adamantine and vitreous, like a diamond Properties of Minerals ★Color - some minerals can be recognized by their color, some minerals can occur in a variety of different colors due to impurities in the chemical makeup of the mineral ★Streak - The color of the streak left by the mineral is sometimes different from the mineral itself Streak test (steak plate)- rubbing the mineral on a porcelain plate ★Hardness - a measure of a mineral’s resistance to abrasion, scaled 1(softest) to 10(hardest) ★Cleavage - can be observed in minerals that tend to break along one or more flat surfaces ☆Perfect - minerals break easily along flat surfaces and are easy to spot ☆Good -minerals do not have such well-defined cleavage planes and reflect less light ☆Poor - toughest to recognize, can be spotted by small flashes of light in certain positions ☆Cleavage planes - individual planes may extend across the whole mineral or more commonly, they may be slightly offset from each other ☆Basal cleavage - one cleavage direction ★Fracture - the tendency of a mineral to break along curved surfaces without a definite shape ★Specific gravity - relative weight of the mineral to an equal volume of water ★Tenacity - how well a mineral resists breakage ☆Brittle - mineral crushes to angular fragments ☆Malleable - can be modified in shape without breaking, and can be flattened to a thin sheet ☆Sectile - can be cut with a knife into thin shavings ☆Flexible - mineral bends but does not regain its shape once released ☆Elastic - mineral bends and regains its original shape when released ★Acid Test - when carbonates are treated with cold, dilute hydrochloric acid, they will effervesce, foam, and bubble and give off carbon dioxide gas. When sulfides are they will give off a rotten egg odor ★Fluorescence - some minders will fluorescence in brilliant colors when vied with ultraviolet light, uv is normally visible to the human eye, UV the source can damage eye ★Gem - a mineral or rock that is rare and has a value Ex. birthstones Petrology - the study of rocks; igneous, metamorphic, and sedimentary, the processes that form and transform them ★Mineralogy - the study of chemistry, crystal structure and physical properties of the mineral constituents of rocks ★Rock - is any naturally occurring solid mass or aggregate of minerals or mineraloid matter, can be categorized by minerals included, chemical composition, and the way in which it formed, can be classified as igneous, sedimentary, and metamorphic ★Igneous rocks - form when hot, molten rock crystallizes and solidifies, classified according to where it solidifies, texture, and chemical composition ☆Extrusive(volcanic) rocks - forms when lava cools and becomes solid ☆Intrusive(plutonic) rocks - forms when magma solidifies within the crust Naming and identifying Igneous rocks in terms of texture ★Texture - size, shape, and arrangements of its mineral grains, or crystals ★Aphanitic - magmas that rapidly cooled, fast cooling prevents crystal from growing very large ★Phaneritic - magmas that slowly cooled, slow cooling gives crystals enough time to grow ★Porphyritic - large crystals are set in finer-grained, or glassy groundmass, occur in course, medium, caused by the varied rate of cooling ★Glassy - cooling that was extremely fast, no crystals could form Pyroclastic(fragmented) - texture occurs when explosive eruptions blast the lava into the air resulting in fragmental, typically glassy material which fall as volcanic ash, lapilli and volcanic bombs ★Vesicular - rock being pitted with many cavities(vesicles) at its surface and inside Naming and Identifying Igneous Rocks in terms of Composition ★Felsic rocks - rich in feldspar and silica ★Mafic rocks - high magnesium and iron contents ★Untramafic rocks - especially high magnesium and iron concentration ★Intermediate rocks - between those of granite and basalt Bowen’s Reaction Series - important tool in the study of igneous rocks, can be used to identify the original composition of the magma and the conditions under which it cooled and solidified Sedimentary rocks - formed by compaction and cementation(lithification) of mineral organic particles at the earth’s surface Sedimentation - name for the processes that cause these particles to settle in place Types of Sediments ★Lithogenous sediments- land via rivers, ice, wind, and other processes ★Biogenous sediments - from organisms like plankton, when their exoskeleton break down ★Hydogenous sediments - chemical reactions in water ★Cosmogenous sediments - derived from extraterrestrial sources, 2 forms: microscopic spherules(asteroid) and large meteor debris ★Formation -Erosion and transportation - eroded sediments end up in the water and begin to settle down -Deposition - with time more sediments are added to newly formed sedimentary layers -Compaction - the release of moisture from the sedimentary layers makes the layer compact -Cementation - salt crystals glue the layers to form more compact sedimentary rocks ★Clastic Sedimentary Rocks - composed mainly of minerals transported as solid fragments and then cemented together by minerals that precipitated from solution, composed of particles of weathered rocks; sain grains, pebbles, silt, gravel, and clay, make up 85% of sedimentary rocks ★Organic Sedimentary Rocks - form from the accumulation and lithification of organic debris such as leaves, roots, and other plant or animal matter, rocks that were once swampy sediments or peat beds contain carbon and are black soft and fossiliferous ★Bioclastic sedimentary rocks - wholly or partially comprised of compacted plant or animal remains, often have fossils within them upon discovery ★Metamorphic - started as some other type of rock, has been substantially changed, forms when rocks are subjected to high heat, high pressure, hot mineral-rich fluids Types of Metamorphism ★Contact Metamorphism - occurs when magma moves into rock, changes are driven by a rise in temperature, commonly occurs without deformation, occurs near a body of magma ★Burial Metamorphism - occurs when sedimentary rocks that had undergone diagenesis are buried even deeper ★Regional Dynamothermal Metamorphism -results in large scale deformation and high grade metamorphism, produces the greatest volume of metamorphic rock, occurs in areas of active subduction and mountain building ★Hydrothermal Metamorphism - occurs along mid-ocean ridge spreading centers where heated seawater percolates through hot, fractured basalt, a chemical reaction between heated seawater and basalt results in metamorphism, can occur on continents where crustal rocks are metamorphose by invading hot fluids associated with igneous ★Cataclastic Metamorphism - high pressure results from crushing and shearing of rock during tectonic movement, producing sheared highly deformed rocks called mylonites Agents of Metamorphism ★Heat - provides the energy needed to drive chemical reactions ★Pressure - causes a more compact rock with greater density Types of Metamorphic Rock ★Foliation - the pattern of aligned crystals that results,when a rock is acted upon by a pressure that is not the same in all directions or by a shear stress minerals can become elongated, Types of Foliated Rocks -slate -phyllite -schist -gneiss ★Nonfoliated rocks - forms under low-pressure conditions or under the effects confining pressure, which is equal in all directions Weathering and Erosion ★Weathering is the physical break-down (distingration) and chemical alteration (decomposition) of rocks and minerals at or near Earth’s surface. MECHANICAL WEATHERING ★Frost Wedging is the process by which water seeps into cracks in a rock, expands on freezing, and thus enlarges the cracks ★Salt crystal growth - often occurs when groundwater moves into empty pores or spaces of rock by capillary action. As the water evaporates, salt crystals grow and accumulate, putting pressure on the rock and causing it to break apart. Rocky shorelines and arid regions are common setting for this process ★Pressure-Release Fracturing or Sheeting - when a rock that forms under greatpressure is brought to the surface and overlying rock is eroded away, fractures willform parallel to the outer surface of the rock ★Abrasion - occurs when rocks and sediment grinding against each other wear awaysurfaces. This happens as wind and water rush over rocks. The rocks becomesmoother as rough and jagged edges break off. ★Thermal Expansion and Contraction Thermal expansion - occurs when you heat a material and it gains more internal energy, and as the atoms within the material move around faster, and the material expands. Thermal contraction occurs when you cool the material down, and the atoms don't have that much energy. CHEMICAL WEATHERING ★Oxidation - occurs when oxygen combines with another substances. Sometimes a change in the color of a rock is an indication that oxidation has occurred. One common example of oxidation rust ★Dissolution - occurs when calcite (like limestone) are especially vulnerable to chemical weathering. Carbonic acid slowly dissolves the limestone and enlarges cracks, ultimately enlarging them to such an extent that caverns are formed. ★Hydrolysis - a new solution (a mixture of two or more substances) is formed as chemicals in rock interact with water. In many rocks, for example, sodium minerals interact with water to form a saltwater solution. ★Erosion - is the geological process in which earthen materials are worn away and transported by natural forces such as wind or water. A similar process, weathering, breaks down or dissolves rock, but does not involve movement. agents of Erosion Water (Fluvial) example: rain, streams and rivers and ocean dynamics Wind (Aeolian) Gravity Ice (Periglacial and Glacial) Pedology ★Pedology - is a branch of soil science focusing on the formation, morphology, and classification of soils as bodies within the natural landscape. With few exceptions, Earth’s land surface is covered by regolith (rhegos = blanket; lithos= stone), a layer of rock and mineral fragments produced by weathering ★Soil Texture - refers to the proportions of different particles sizes