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Learn about the characteristics of minerals, including their formation, properties, and how to identify them. Explore the common elements found in minerals and discover the physical properties that can help in mineral identification.
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What is a Mineral? • Naturally occurring, inorganic solid with a crystal structure and definite chemical composition. Pyromorphite
What do all minerals have in common? All: • Are formed by natural processes. • Are NOT alive and NEVER were alive • Have a definite volume and shape • Are elements or compounds with a unique chemical makeup (2 or more elements) • Are made up of particles that are arranged in a pattern that is repeated over and over (called a CRYSTAL)
How do minerals form? • 1) Cooling of magma (hot, liquid rock and minerals inside the earth (from the mantle)) • Fast Cooling = No Crystals (mineraloids) • Medium Cooling = small crystals • Slow Cooling = large crystals
How do minerals form? • 2) Elements dissolved in liquids (usually water) • 3) Changes in pressure and temperature • 4) formation of hydrothermal solutions -when hot solutions touch existing minerals, chemical reactions take place and form new minerals.
.What element are diamonds made from? • . What do all crystals have in common?
Groups of Minerals • Minerals are grouped by the elements they are made of. Beryl (Emerald) Calcite Amethyst
MICA Quartz
BariteBaSo4 Barite on CalciteBaSo4 / CaCO3
Silver Copper Diamond Gold Iron Ruby
QUIZ BREAK
How many mineral groups can you name? Can you tell me some of the examples?
Physical Properties of Minerals(can be used to identify the mineral) Color • Can be misleading • Can vary with the type of impurities
Physical Properties of Minerals(can be used to identify the mineral) Streak • The color of the powdered form of the mineral • The color of the streak can be different than the mineral • Minerals must be softer than the streak plate
Streak…can help identify quartz BUT... http://www.childrensmuseum.org/geomysteries/cube/b3.html
Physical Properties of Minerals(can be used to identify the mineral) Luster • Surface reflection • metallic = shiny like metal • non-metallic = dull, non-shiny surface Pyrite has a metallic luster Calcite has a non-metallic luster
Physical Properties of Minerals(can be used to identify the mineral) Hardness • How easily a mineral scratches materials • Mohs Hardness Scale • Scale from 1 (softest) to 10 (hardest) • Test by seeing if the mineral can scratch different objects (like human fingernail, copper, penny, glass, steel file)
Find out more… • “Electronic” Hardness Test http://www.childrensmuseum.org/geomysteries/cube/b2.html
Physical Properties of Minerals(can be used to identify the mineral) Cleavage & Fracture • The way the mineral breaks • Cleavage—minerals break along smooth, flat surfaces and every fragment has the same general shape • Fracture—minerals that break at random with rough or jagged edges
Crystal form • If space is not restricted, a mineral will exhibit a crystal pattern with a definite number of sides and specific angles.
1. 4. 3. 2. Cleavage or Fracture?
Physical Properties of Minerals(can be used to identify the mineral) Other Properties • Specific gravity (*excellent clue to mineral’s identity) • Attraction to magnets • Bending of light • Reaction with hydrochloric acid • Smell & taste http://www.childrensmuseum.org/geomysteries/cube/b4.html
. If a mineral can scratch your fingernail, the mineral is _______________ than your fingernail. • 2. What is luster?