GEO 102 Lecture 8 Outline of Last Lecture I What the earth is made of Outline of Current Lecture II How to ID a mineral III How geologists ID a mineral IV Families of minerals and how they form V Types of rocks Current Lecture How do you ID a mineral Properties mass hardness luster shape cleavage Etc like in your lab section Don t be fooled by color size etc How do geologists ID a mineral In the field we use the same techniques you do in your lab section In the lab we use other properties These 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 chemical composition structure Light bends according to the way a substance changes the light waves Diffraction is the way a wave is interfered with by a material Families of Minerals silicates largest group Harder minerals Common Quartz feldspar garnet Some subfamilies are important Clay minerals carbonates carbon Oxygen soft rock not near as common as silicates but are abundant above the Earth Made by animals and humans and almost always form on the Earth s surface Softer Less common Calcite aragonite sea shells Mineral Groups carbonates CaCO3 and variants Important for deciphering earth history Often produced by organisms Coral sea shells microrganisms etc Much of Alabama is made of carbonates Practical Mineralogy Only a few minerals make up most of the Earth s solid materials Quartz potassium Feldspar Plagioclase Feldspar Olivine Pyroxene Amphibole Mica Calcite How do they form Several ways from cooling magma from solution in water solution in other fluids in or around living cells Rocks Igneous rocks rocks that form from magma intrusive Rocks that form from lavaextrusive From magma or lava Metamorphic Altered through heat and or pressure Sedimentary Reformed bits of other rocks broken down or from solution
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