3. Luster The way in which light is reflected from the surface a. Metallic - shines like polished metals, rust, heavy b. Nonmetallic - no metallic luster 1) glassy, clear 2) pearly, white 3) greasy 4) dull 5) earthy nonmetallic metallic
4. Hardness a. the resistance of a mineral is compared to glass by scratching it against a glass plate (5.5) b. hardness of a mineral is determined by Moh's Scale of Hardness (1 – 10)
5. Cleavage The tendency of a mineral to split along flat, even surfaces.
Fracture -Uneven breakage of a mineral. (minerals that do not have cleavage have this!)
Other Properties: a. Magnetic b. React with dilute hydrochloric acid by effervescing bubbles c. Taste (salty) d. Fluorescence e. Double refraction f. Radioactive
Minerals Relationship to Rocks: Minerals form rocks. Most rocks are composed of one or more minerals Monominerallic - composed of one mineral Polyminerallic - composed of more than one mineral 10 - 15 minerals form most all of the rocks on Earth, they are called rock-forming minerals.
Silicates minerals (SiO 4 )– two minerals combine to form a compound. When they combine they create a structure called the Silicon-Oxygen Tetrahedron
3 Rock Types: IgneousSedimentary Metamorphic Rocks are classified based on their: Origin In other words, what environment did they form in??? Crystals Sediments Recrystallized crystals
Igneous Rocks Formed by cooling and solidification of lava or magma. Lava: extrusive Magma: intrusive
Igneous Rocks A. Igneous Rocks Intrusive- cools and solidifies from magma (beneath Earth’s surface), making larger crystals due to slow cooling. Granite (coarse crystal texture)
Extrusive – cools and solidifies from lava (at or near Earth’s surface), making smaller crystals due to faster cooling. Obsidian (glassy texture)Pumice (glassy texture with vesicles)
Igneous Rock Characteristics Felsic- forms light-colored rocks that are high in Al, low density. Mafic- forms dark-colored rocks that are high in Mg and Fe, high density. Vesicular- gas bubbles or air pockets.
Cooling Time Graph (the longer it takes to cool, the bigger the crystals!) As time increases, crystal size increases.
Name a very light-colored, glassy, extrusive rock with bubbles.
Metamorphic Rocks Form from metamorphism (change) that is caused by heat and pressure. Usually form deep in the Earth's crust Causes a change in the rocks 1. makes the rock more dense 2. separates the rock into layers (banding)
Metamorphic rocks have been changed from a pre-existing rock. Caused by extreme heat and/or pressure. (regional) Happens over wide “regions.” Caused by contact with extreme heat from a nearby volcano (contact). Occurs when the rock is in close contact with volcanic heat.
Types of Metamorphic Rocks: 1. Contact Metamorphic - Rocks that form from being close to a heat source (magma) 2. Regional Metamorphic a. caused mainly by pressure b. usually cover large areas c. form during tectonic activity d. most metamorphic rocks are formed from regional metamorphism
Metamorphism happens where lava or magma touches other rocks. What will this limestone rock metamorphose into?
Classification of Metamorphic Rocks Non-foliated - no visible layers (distorted crystals) Marble
Foliated Metamorphic Rock – mineral alignment a. visible layers in the rock b. form from extreme pressure which flattens the minerals into layers c. different mineral densities may produce alternating light and dark bands of minerals (banding) A “GNEISS” ROCK
Sedimentary Rocks: Rocks formed from sediments on Earth’s surface.
Sedimentary Rocks form from sediments that go through cementation & compaction EXAMPLES OF SEDIMENT SIZE FROM LARGEST TO SMALLEST
Three main types 1. Clastic - made from other existing rock fragments. Clastic rocks are identified by the size of the fragments. 2. Chemical - form from minerals once dissolved in water. 3. Organic - formed from once living organisms.
Features of Sedimentary Rocks: Stratification - layering of rocks caused by different types of sediments being deposited
Fossils – only found in Sedimentary Rocks. These are the imprints left by a once-living organism.
1. Made from sediments or rock material that has been broken down in some way. 2. Sedimentary rocks are usually formed under water. 3. Often layered. 4. Are the only rocks that contain fossils! Key Features of Sedimentary Rock
5.Clastic (fragmental) – made by compaction and cementation of sediments. See Earth Science References Tables
Chemically formed rocks: Evaporites 1. Formed when water carrying minerals evaporates and leaves the minerals behind. 2. Are identified by the minerals present (such as halite forms Rock Salt) See Earth Science Reference Tables
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