Rocks & Minerals
Mineral - a naturally occurring, inorganic solid that has a crystalline structure and a definite chemical composition For the Love of God A platinum cast of a skull from an actual person that lived between 1720 and 1810. He was a 35 year old man from Europe. The teeth are original. The skull is covered with 8,601 flawless diamonds. Cost 14 million to produce. Sold for 50 million in 2007.
Naturally occurring: not man-made copper and zinc are both minerals; brass (a mixture of copper and zinc) is not a mineral
Inorganic: not from anything that was at one time living gold is a mineral; coal is not a mineral
Crystal structure: the particles line up into a regular, repeating structure
Definite chemical composition: made up of specific elements in a set amount (Ruby = Al 2 O 3 )
Properties of Minerals 1) Color - many minerals have the same color (ex. gold and fool s gold), so color is rarely enough information to identify a mineral
occasionally, color is enough (malachite and azurite)
2) Streak - the color of a mineral s powder; tested with a streak plate
3) Luster - the way a mineral reflects light from its surface (ex. metallic, glassy, waxy, dull, earthy)
4) Density - (mass/volume) can be used to identify minerals (density of gold = 19.93 g/cc; fools gold = 5 g/cc)
5) Hardness - determined by a scratch test; a mineral can scratch any mineral softer than itself, but will be scratched by any mineral that is harder
Mohs hardness scale ranks 10 minerals from softest to hardest
6) Crystal structure - shape of the mineral s crystals
7) Fracture and Cleavage - the way a mineral breaks apart fracture: irregular break; jagged, rough surface
Cleavage: splits easily along flat surfaces
8) Special properties - magnetism, fluorescence, radioactivity, reaction to acids
4th Quarter Extra Credit Opportunity 20 points extra credit for a package of cookies Due: Thursday, March 24th
For each sample: # Name Picture (colored) At least two distinguishing properties Example: #11 sulfur Bright yellow Doesn t scratch glass
Rock Formation - rocks are a mixture of minerals and other materials
some rocks contain only one type of mineral; others are made of many different minerals combined together All minerals are rocks, but not all rocks are minerals.
Igneous Rock - forms from cooling magma or lava Extrusive rock forms from lava that cools on the earth s surface (ex. basalt, obsidian, pumice)
Intrusive rock forms from magma that hardens beneath the Earth s surface (ex. granite) Intrusive rock usually has larger grains than extrusive rock since it takes longer to cool (more time for crystals to grow)
Igneous rocks are used as building materials because they are hard, dense, and durable
Sedimentary Rock - forms when sediment (small, solid pieces of material that come from rocks or living things) is pressed and cemented together
5 steps of sedimentary rock formation: 1) Weathering - rocks are broken down into sediments by physical and chemical processes
5 steps of sedimentary rock formation: 1) Weathering - rocks are broken down into sediments by physical and chemical processes 2) Erosion - sediments are carried from their source
5 steps of sedimentary rock formation: 1) Weathering - rocks are broken down into sediments by physical and chemical processes 2) Erosion - sediments are carried from their source 3) Deposition - sediments are deposited in a new area
5 steps of sedimentary rock formation: 1) Weathering - rocks are broken down into sediments by physical and chemical processes 2) Erosion - sediments are carried from their source 3) Deposition - sediments are deposited in a new area 4) Compaction - sediments are squeezed together under the pressure new layers of sediment above
5 steps of sedimentary rock formation: 1) Weathering - rocks are broken down into sediments by physical and chemical processes 2) Erosion - sediments are carried from their source 3) Deposition - sediments are deposited in a new area 4) Compaction - sediments are squeezed together under the pressure new layers of sediment above 5) Cementation - dissolved minerals crystallize and glue particles of sediment together
3 Types of Sedimentary Rocks Clastic Rock forms when rock fragments are squeezed together; the fragments can be very small or quite large ex. shale (from clay), sandstone, conglomerate (rounded rocks), and breccia (rock fragments with sharp edges)
Organic Rock forms when the remains of plants and animals are deposited in thick layers ex. coal (from swamp plants) and limestone (from coral and shells)
Chemical rock forms when minerals dissolved in solution crystallize (water evaporates or minerals precipitate out of solution) ex. rock salt, some limestone
Sedimentary rocks are also used as building materials (Limestone) (Sandstone)
Metamorphic Rock - forms from an existing rock changed by extreme heat and pressure deep within Earth s crust
Foliated rocks have mineral grains arranged in parallel layers or bands ex. gneiss (from granite), slate (from shale)
Nonfoliated rocks have mineral grains arranged randomly ex. quartzite (from sandstone), marble (from limestone)
Metamorphic rocks are important materials for building and sculpture
The Rock Cycle - a series of processes that slowly changes rock from one kind to another
Fossils - the preserved remains or traces of living things; usually found in sedimentary rock
most fossils form when living things die and are buried by sediments the sediments slowly harden into rock and preserve the shape of the organism
Types of Fossils Mold and cast: a mold is a hollow area in the sediment in the shape of a dead organism; a cast is a solid copy of an organism s shape, formed when minerals seep into the mold
petrified fossil - forms when minerals replace all or part of an organism (ex. petrified wood)
carbon film - an extremely thin coating of carbon on rock
trace fossils - provide evidence of the activities of prehistoric organisms - ex. dinosaur footprint
preserved remains - actual remains of an organism encased in tar, amber, or ice which prevent the organism from decaying fully (ex. mosquito, woolly mammoth)
Paleontologist a scientist who studies fossils
Relative Age of Rock - the age of a rock compared with other rocks
Law of Superposition - in horizontal layers of sedimentary rock, each layer is older than the layer above it and younger than the layer below it
Unconformity - a place where an old, eroded rock surface is in contact with a new rock layer; caused by erosion, faults, and folding
Index fossils - if the same type of fossil is found in rock layers in different areas, those layers are the same age
an index fossil must be widely distributed and represent a type of organism that existed only briefly
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Igneous Inter-grown Crystals Bubbles Glassy Sedimentary Layers Fossils Fragments Metamorphic Warped/Distorted Dense Foliation/Bands Hints for Classifying Cookies
Igneous Granite Pumice Obsidian Sedimentary Sandstone Limestone Conglomerate Metamorphic Marble Slate Gneiss Rock Examples