What is a mineral?

Properties of Minerals

Mineral

5 characteristics:

– naturally occurring (not

made by people)

– inorganic (cannot come

from living things)

– solid (definite shape and

volume)

– crystal structure (regular, repeating pattern)

Element

Compound

Crystal Shape

pure substance that cannot be broken down

makes up all minerals

made of one kind of atom (smallest part of an element)

two or more elements chemically combined

determined by arrangement of atoms

Silicate Minerals

Nonsilicate Minerals

contains a combo of silicon, oxygen, and one or more metals

make up more than 90% of crust

ex. quartz, feldspar, mica

does not contain compounds of silicon and oxygen

ex. copper, calcite, fluorite

Identifying Minerals

Color

Streak

-easily observed physical property

-only a few minerals ALWAYS have the same color

-color of a mineral’s powder

-streak color does not vary, even though physical color can

-observe by rubbing on porcelain tile

Luster

Density

-how light reflects off surface

-ex. shiny, metallic, glassy, earthy, waxy, pearly

-mass in a given space (M/V)

-density always stays same, no matter what size the mineral is

Hardness

Mohs Hardness Scale

-test invented by Friedrich Mohs

-ranks 10 minerals from softest (1) to hardest (10)

-scratch test

-softest = talc

-hardest = diamond

Cleavage

Fracture

splits easily along flat surfaces

-depends on how crystals are arranged

-ex. mica

-breaks apart in an irregular way

-shell shaped, jagged, crumble

-ex. quartz

Special Properties

-fluorescence: glows under UV light

-magnetism

-optical: bends light

-reactivity: reacts to acids

How Minerals Form

Crystallization

Geode

-atoms are arranged to form materials with a crystal structure

-forms two ways:

1. magma/lava

2. materials dissolved in water

-round, hollow rock

-lined with mineral crystals

Minerals from Magma/Lava

-form as hot magma cools inside crust; lava hardens on surface

-liquid to solid state

-size of crystals depends on rate at which magma cools

*deep below surface – cools slowly = large crystals

*close to surface – cools quickly = small crystals

Solution

Minerals from Solution

-mixture

-one substance completely dissolves in another

-elements and compounds dissolved in water leave a solution

-crystallization occurs

Formed from Evaporation

Formed from hot water solutions

-when solutions evaporate, water turns to gas and leaves minerals behind to crystallize

-ex. seas evaporate leaving behind gypsum and calcite

-magma heats ground water

-minerals dissolve in water

-as solution cools, minerals leave solution and crystallize

-ex. Gold, copper, sulfur, pyrite.

Vein -narrow channel of mineral different from surrounding rock

-solutions of hot water and metals flow thru cracks in rock

-metals crystallize into veins

-resembles streaks of fudge in ice cream

Mineral Resources

Gemstones

-hard, colorful mineral with glassy luster

-valued for color, luster, and durability

-mainly for jewelry and decoration

Metals -source of metals like aluminum, iron, copper, and silver

-useful for:

*stretching into wires,

*flattening,

*hammering without breaking

Other Uses

Ore

-used in foods, medicines, fertilizers

-ex. talc = talcum powder

quartz = glass & watches

gypsum = cement, stucco

-rock that contains metal or useful mineral

-metals & minerals can be separated from ore

Prospector

Mining

-anyone who searches for ore deposit

-look for certain features on earth and study maps of rocks

-three types:

strip mines

open pit mines

shaft mines

Strip Mines -earthmoving

equipment scrapes away soil to expose ore

Open Pit Mines -earthmoving equipment digs a big pit and removes ore deposits

Shaft Mines -network of tunnels that follow veins of ore

Smelting -process in which

metal is removed from rock (ore)

-ore is mixed with other substances and melted