Minerals:
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inorganic, solid materials found in nature
o Inorganic = NOT made by plants or animals
Have an orderly arrangement of atoms that create a crystal shape that are different for each
mineral (like a snowflake)
How do minerals form?
1. The COOLNG of magma or lava (melted rock material)
a. As it cools, the atoms combine in orderly patterns forming minerals
b. Can happen UNDER the Earth’s surface (MAGMA) and ABOVE Earth’s surface (LAVA)
2. Evaporation: Dissolved minerals can crystallize when water evaporates.
3. Precipitation:
a. Rain, Slow, Sleet, etc.
b. Water can only hold so much dissolved mineral, so the extra mineral SEPARATES and
forms a solid.
Formation Clues:
You can tell how a mineral is formed from how it looks.
1. Formed from Slow cooling magma: large mineral grains that fit together like a puzzle.
2. Formed from Open pockets within rocks: large, perfect crystals (the minerals had a lot of space
to grow)
Properties of Minerals:
You can identify minerals based on their properties:
1. Crystals
a. Any solid that has an orderly pattern of atoms is a crystal
i. ALL MINERALS HAVE THIS
b. Crystals have faces.
i. You can identify different types of minerals by the number of faces they have
2. Cleavage and Fracture:
a. Cleavage: If a mineral splits into pieces with smooth, regular planes that reflect light
b. Fracture: If a mineral splits into pieces with jagged edges, that looks like a block of
cheese
 Scenario: If you hit a mineral with a sledge hammer:
i. The pieces break off with smooth edges = CLEAVAGE
ii. The pieces break off with rough edges (CHEESE) = FRACTURE
3. Color:
a. Color is not the best indicator because sometimes the minerals can be in the form of
different colors.
4. Streak and Luster:
a. When you scrape a mineral against an unglazed white tile it produces a streak of color.
i. This streak of color is NOT always the same as the color of the mineral. This
streak is the TRUE color of the mineral.
b. Luster: How does light reflect from the surface of a mineral?
i. Shiny, dull, pearly?
5. Hardness:
a. The Mohs scale: classifies minerals from 1(softest) - 10 (hardest).
b. You can tell how hard a mineral is by scratching one mineral on a 2nd mineral as long as
you know the 2nd mineral’s hardness.
c. DIAMOND is the hardest mineral (LEVEL 10 Hardness)
6. Specific Gravity
a. Weight of a mineral compared to the weight of an equal volume of water.
b. Example: “Pyrite is 5 times heavier than water”
7. Other Properties:
a. Magnetic: Some minerals will have magnetic properties to metal
b. Fizz: Some minerals, when put into a liquid, will fizz.
c. Taste: Some minerals have distinct tastes (SALT is a mineral!)
The Most Common Minerals:
 Rock forming Minerals: minerals that form the rocks which make up mountains
 SILICATES: made up of Silicon and Oxygen
 Carbonates: made up of Carbon and Oxygen
 Gems:
 rare minerals that can be cut and polished, and are expensive
 Example: Diamond, Garnet
 Ores:
 Contain substances that can be sold
 Many metals come from ores
i. IRON (Scrap metal) – from Hematite
ii. Lead (for batteries) – from Galena
 We get Ores through MINING, which is the process of extracting ores from Earth.
 Ore Processing: we heat up the mined ore to get rid of unwanted substances, then
refine and purify the mineral.
Rocks:
I. Igneous Rocks: (GRANITE)
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When melted rock cools
o Extrusive: ON Earth’s surface
 Usually formed from Lava and have a smooth, glossy appearance.
 How?
 Volcanoes erupt and shoot out lava
 Fissures (crack in Earth’s surface that Lava comes up out of)
o Intrusive: BELOW Earth’s surface
 From MAGMA
 How?
 When huge globs of magma from within Earth’s surface is forced
upward towards the Earth’s crust, but does not make it.
Chemicals within the melted rock determine its’ color
o Intrusive = Light color
 Ex: Granite
o Extrusive = Dark color
 Ex: Basaltic
II. Sedimentary Rocks:
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Pieces of broken rocks, shells, mineral grains, and other materials
Example: Sand at the beach
Can be carried around by mudslides, glaciers, waves and rivers.
1. Detrital Rocks:
 Grains or minerals that have moved and been deposited by water, ice, gravity, or wind.
 Identify: to use the size of the grains that make up the rock
1. Shale: Smallest, clay
2. Siltstone: Rough, silt sized grains
3. Sandstone: Larger, sand-sized grains
4. Pebbles: Largest
2. Chemical Rocks:
 Form when seawater (with dissolved minerals) evaporates.
o Mineral-rich water from geysers, hot springs, or salty lakes evaporates.
3. Organic Rocks:
 Formed over millions of years.
 When living matter dies, it piles up and then is compressed into rock.
o COAL is the organic rock from PLANTS when they die.
o If it happens in the ocean, we get LIMESTONE (organic rock)
4. Fossils:
 Remains or trace of a once living plant or animal
o Dinosaur bone, footprints, etc.
What can Change Rocks?
 Heat from magma/lava
 Pressure
 Weathering/erosion
III. Metamorphic Rocks:
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New rocks formed from existing rocks by HEATING or SQUEEZING (increased pressure).
o NOT BY MELTING
2 types:
1. Foliated: visible layers or elongated grains of minerals
a. GNEISS (from granite), SLATE
2. Nonfoliated: no visible layers or elongated grains
The Rock Cycle: a way to describe how different rocks are related to each other.
*remember the chart in the textbook.