EAR 110 1st Edition Lecture 7Outline of Previous Lecture:I. Divergent Boundary ReviewII. Ocean-Ocean convergent boundaryIII. Ocean-Continent Convergent boundaryIV. Continent-continent convergenceV. Transform BoundaryVI. Plate MovementVII. Geometry of plate boundariesVIII. Earth’s Magnetic FieldIX. Evidence for plate tectonicsX. Formation of linear islands and seamount chainsXI. Why is South America lopsided?Outline of Current Lecture:I. IntroductionII. MineralsIII. RocksIV. Crystalline structureV. Atomic scale of mineral cleavage Chapter 4: Earth MaterialsI. Introductiona. Regions of earth are composed of different materials i. Example: landscape is mostly granite with some small pockets of tourmaline, also some loose sedimentb. These differences in material can be observed at different scalesi. Landscape scaleii. Outcrop scale – example: granite looks all the same compositioniii. Close up scale – example: distinguish individual minerals in graniteiv. Thin section (microscope) – example: see mineral crystalsII. Mineralsa. Definitioni. Solidii. Naturally occurringiii. Inorganiciv. Ordered internal structure1. Determines how material breaks, strength, external appearance etc.v. Specific chemical compositionb. Distinguishing propertiesi. Crystal formii. Cleavage or no cleavageThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.iii. Color1. Gives insight into composition of mineral2. Trace amounts of different elements can change coloriv. Luster1. How light interacts with mineral2. Example: greasy, metallic, chalkyc. Tests performed on minerals for properties and identificationi. Hardness (Moh’s scale of hardness)ii. Effervescence1. Is a property of minerals when HCl (acid) fizzes when in contact a. Example: calciteiii. Streak (color left on ceramic plate)iv. Magnetism v. Density/specific gravityIII. Rocksa. Definitioni. Aggregate of one or more mineralsb. Typesi. Crystalline 1. Composed of visible or microscopic crystals2. No open pore spaceii. Clastic1. Composed of pieces of rock2. Generally porous3. Example: sandstone conglomerate: granite clasts surrounded by sandstoneIV. Crystalline structure a. What controls a crystal’s shape?i. Sizes and packing of atoms; the way ions are arranged in materialii. Example: halite (NaCl, salt) - internal structure is cubic – creates cubic cleavageb. Crystalline structurei. Is the orderly arrangement of atoms in a repeating patternii. Cation = positively charged ioniii. Anion = negatively charged ionc. How are atoms arranged in a mineral?i. In cubes – cubic crystals1. 8 oxygen atoms around a single cation in the center of the cubeii. tetrahedron crystals (pyramids)1. Most common is silicates – one silicon atom in center of 4 oxygen atomsiii. Octahedrons (double pyramids)V. Atomic Scale of Mineral cleavagea. Some bonds in mineral may be stronger than othersi. Mineral will break along weak bondsii. If long lines of weak bonds  forms sheets or planar cleavageb. If bonds are equal in strength, mineral will break along multiple planesc. If no cleavage and the mineral breaks in nearly any direction, called fractured. Directions of cleavagei. One dominant direction – sheets (example: biotite or mica)ii. 2 dominant directions1. Perpendicular (right angles)2. Non perpendicular iii. 3 dominant planes1. Perpendicular (cubes, halite)2. Non perpendicular (at an angle;