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MINERALS. What is a mineral? Minerals have a definite chemical composition unique to that mineral That chemical composition can determine what humans use that mineral for
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What is a mineral? • Minerals have a definite chemical composition unique to that mineral • That chemical composition can determine what humans use that mineral for • For example, the mineral gibbsite (Al(OH)3) can be processed to release the aluminum atoms within it to be used in manufacturing
5 Fundamental Mineral Characteristics • Definite chemical composition • Orderly arrangement of atoms • Naturally occurring • Inorganic • Solid
Definite Chemical Composition • The same elements will make up the same minerals • For example, table salt, or halite, is always NaCl…composed of a combination of sodium (Na) and chlorine (Cl) atoms
Orderly Arrangement of Atoms • Atoms are arranged in an orderly fashion so that a crystal forms • For example: halite crystals and the atoms that produce them
Naturally Occurring/Inorganic Solid • Was not produced by life processes or humans • Is not a liquid or a gas
How do minerals form? • Cooling and solidification of magma/lava
Precipitating out of a solution, such as when water evaporates leaving salt (halite) behind
Rocks Are Made Up of Minerals • This granite has several minerals within it
What are minerals made up of? • Minerals are a mixture of 1 or more elements • Certain elements contribute color to minerals, but color alone is not a definite way of identifying them • Many minerals contain the same elements • Use your ESRT to identify the elements
Mineral Identification: Appearance • Color and appearance can help identify some minerals, but it is usually not enough Pyrite Gold
Mineral Identification: Hardness • Hardness is a measure of how easily a mineral can be scratched • In our class “hard” minerals are able to scratch glass while “soft” minerals do not • Talc is a very soft mineral and can be scratched by a fingernail • Diamonds are very hard and can only be scratched by another diamond
Mineral Identification: Mohs Scale • The Mohs Scale assigns a number to a mineral’s hardness • A diamond is a ’10’ since it is the hardest mineral • Talc, being one of the softest, is assigned a ‘1’
Mineral Identification: Luster • There are two types of luster we are concerned with in this course: metallic and non-metallic • Metallic luster is when a mineral appears to be made of metal • Non-metallic luster can be a variety of other colors including minerals that look like glass
Mineral Identification: Streak • The streak of a mineral is the powder left behind when a mineral is crushed or is rubbed against an unglazed porcelain tile
Mineral Identification: Cleavage and Fracture • Cleavage and fracture describe how a mineral breaks • Cleavage is a mineral breaking along a flat plane • Fracture is uneven and random breaking
Mineral Identification: Density • Determining a mineral’s density sometimes help determine what it is • Recall: Density = mass/volume • Example: This galena sample is very dense because it contains a lot of lead
Mineral Identification: Reaction with Acid/Magnetic • Some minerals bubble when acid is dropped onto them • Other minerals are magnetic
Minerals Have a Variety of Uses • Jewelry • Electronics • Abrasives • Lubricants • A source of metal/other useful elements