Transcript Minerals
Rocks & Minerals Minerals Saddle-shaped pink dolomite crystals. What is a Mineral? Naturally Occurring Inorganic Solid Definite Chemical Formula Definite Crystal Structure Galena Beryl Naturally Occurring Formed by natural processes not in the laboratory. - Is an Ice Cube a mineral? - Is the ice on the windshield of a car a mineral? - What about the ice in your refrigerator? Inorganic Formed by inorganic processes; not living Does not contain chains of carbon atoms Solid Not gas or liquid H2O as ice in a glacier or a snowflake is a mineral, but liquid water in the ocean is not. The element mercury is a metal that’s a liquid at room temperature/pressure. Liquid mercury is NOT a mineral! Definite Crystal Structure Highly ordered atomic arrangement of atoms in regular geometric patterns Pyrite Fluorite K-spar Fluorite Kyanite 8 Tourmaline Crystal Structure of Ice Definite Chemical Formula Minerals are expressed by a specific chemical formula -Gold (Au) -Calcite (CaCO3) -Quartz (SiO2) -Pyrite (FeS2) Composition of the Earth’s Crust Eight Elements that make up over 98% of Earth’s Crust -Oxygen (O) -Silicon (SI) -Aluminum (Al) -Iron (Fe) -Calcium (Ca) -Sodium (Na) -Potassium (K) -Magnesium (Mg) Where Do Minerals Come From? Crystallize from magma and lava. Olive crystallizes from mafic magma. Precipitate from water due to evaporation. How Are Minerals Identified? Color Luster Hardness Streak Density Crystal Shape Cleavage and Fracture Special Properties Color Usually the first and most easily observed -Some minerals are always the same color -Some minerals can have many colors ROSE QUARTZ QUARTZ SMOKY QUARTZ Luster General appearance of a mineral surface in reflected light Glassy-Obsidian Hardness Resistance to scratching by different items; “scratchability” Mohs Hardness Scale >2 fingernail 3 penny ~5 Steel of a pocket knife 5.5 Window Glass 6.6 Steel of a file 7 quartz crystal Mohs Mineral Hardness Scale 1) Talc Softest 2) Gypsum 3) Calcite 1 5 4) Flourite 5) Apatite 9 2 6) Feldspar 6 7) Quartz 8) Topaz 3 7 9) Corundum 10) Diamond 10 Hardest 4 8 Streak The color of a finely powdered mineral Determined by rubbing the mineral on a piece of unglazed porcelain (streak plate) Density The amount of matter in a given space (Mass/Volume) Crystal Shape Minerals have a characteristic crystal shape resulting from the atomic packing of the atoms when the mineral is forming Cleavage and Fracture Cleavage is the tendency of a mineral to split or crack along parallel or flat planes One direction of cleavage = basal cleavage (biotite mica). Octahedral Cleavage forms bi-pyramids (Fluorite) Rhombohedral cleavage forms “smushed” cubes (calcite). Cleavage and Fracture Fracture occurs when a mineral breaks at random lines instead of at consistent cleavage planes. Conchoidal fracture is what gives quartz, obsidian, chert, and flint those supersharp edges! Quartz has no cleavage and instead exhibits conchoidal fracture. Special Properties Magnetism (Magnetite) Optical Properties (calcite and ulexite) Glowing under ultraviolet light (Fluorite) Salty taste (Halite) Smell (Sulfur) Magnetite Reaction to weak acids (Calcite) Economic Importance of Minerals Minerals are in many things we see and use everyday such as; bricks, glass, cement, plaster, iron, gold Every American Requires 40,000 Pounds of New Minerals per Year at this level of consumption the average newborn infant will need a lifetime supply of: -795 lbs of lead (car batteries, electric components) -757 lbs of zinc (to make brass, rubber, paints) -1500lbs of copper (electrical motors, wirings -3593 lbs aluminum (soda cans, aircraft) -32,700 lbs of iron (kitchen utensils, automobiles, buildings) -28,213 lbs of salt (cooking, detergents) -1,238,101 lbs of stone, sand, gravel, cement (roads, homes, etc.) Rocks Rocks Made of two or more different minerals that have been: cemented together squeezed and heated together melted and cooled together. Types of Rocks Igneous Sedimentary Metamorphic Igneous Rocks Most igneous rocks are produced deep underground by the cooling and hardening of magma Sedimentary Rocks Formed from the breaking apart of other rocks (igneous, metamorphic, or sedimentary rocks) and the cementation, compaction and recrystallization of these broken pieces of rock Fact about the Mississippi River Did You Know? The Mississippi River carries an average of 436,000 tons of sediment each day It moves an average of 159,000,000 tons of sediment a year Metamorphic Rocks Formed from heat and pressure changing the original or parent rock into a completely new rock. The parent rock can be either sedimentary, igneous, or even another metamorphic rock. The Rock Cycle The diagram of the rock cycle shows how the earth's rocks are changed again and again Classification of Igneous Rocks Composition-refers to the minerals that make up the rock Texture-shape, size, arrangement and distribution of minerals that make up the rock Composition Extrusive- Formed from lava; volcanic Obsidian Pumice Intrusive- Formed deep within the earth Granite Textures Glassy Obsidian Fine-grained Basalt Coarse-grained Granite Porphyritic Granite Classification of Sedimentary Rocks Clastic Rocks- Made of the fragments of previously existing rocks Organic Rocks- Come from organisms Chemical Rocks- Formed by inorganic processes such as evaporation Clastics Rocks Conglomerate Sandstone Mudstone Organic Rocks Limestone Coquina Fossiliferous Limestone Chemical Rocks Limestone Metamorphic Rocks Foliated- Parallel alignment of flattened mineral grains and pebbles Unfoliated-Rocks that are not banded and do not break into layers Foliated Gneisse Unfoliated Marble Distribution of Rocks in the U.S.