Lesson 1Properties of Minerals

What is a mineral?

● A mineral must have 5 specific characteristics to be considered a mineral

a. Naturally occurring - formed by natural processes. b. Solid - must have a definite shape and volume. c. Crystal structure - the repeating pattern of a mineral’s particles form a solid called a

crystal.d. Inorganic processes - formed from materials that are not part of living things. e. Chemical composition - minerals always contain specific elements in specific

amounts.

What is a mineral?

● Almost all minerals are compounds○ In a compound, two or more elements are combined and end

up with the same properties ○ Cinnabar is made of sulfur (a yellow solid) and mercury (a

silver liquid) and looks like shiny red crystals!

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What is a mineral?

● Different minerals are made of different elements○ A crystal of quartz is made up of one atom of silicon and two

atoms of oxygen○ Garnet minerals are made up of three atoms of silicon for

every twelve atoms of oxygen

How are minerals identified? ● Geologists have identified more than 4,000 minerals● Each mineral has characteristic properties that are used to

identify it:○ Color - only a few minerals have their own unique color.○ Streak - the streak of a mineral is the color of its powder. The streak color and color

of the actual mineral are usually very different! ○ Luster - luster is how the mineral looks, either metallic or silky or waxy or glassy! ○ Hardness - the Mohs Hardness Scale is used to rank the hardness of minerals from

1-10 by using a scratch test.

How are minerals identified? ● Each mineral has characteristic properties that are used to

identify it:○ Density - the mass of the sample is divided by the volume. ○ Crystal structure - minerals have crystals that are shaped differently that are

classified by the number of faces or sides on the crystal.○ Cleavage & fracture - a mineral that splits easily along flat surfaces has a property

called cleavage. Minerals that split in very irregular patterns have a property called fracture.

○ Special properties - conducting electricity, glowing under UV light, or magnetism.

How do minerals form?

● A geode is a rounded, hollow rock that is lined with mineral crystals ○ Crystals form inside a geode when water seeps into a crack of the rock ○ Over time, crystallization occurs - the process where atoms are arranged to form a

substance that has a crystal structure

● Generally, minerals form in 3 ways:○ By organic processes○ From solutions○ As magma and lava cool

How do minerals form?

● Minerals form from organic processes○ Clams and corals produce shells made out of the mineral calcite

● Minerals form from solutions○ A solution is a mixture where one substance is dissolved in another○ When an element or compound is left in water, crystallization occurs○ When a solution evaporates, the water leaves behind crystals

● Minerals form from magma and lava○ As hot magma or lava cools to a solid state, they form crystals○ Size of crystals depends on how fast the magma cools, the amount of gas in the

magma, and the chemical composition of the magma

How do minerals form? Examples of minerals formed from each process

By evaporation By lava cooling By magma cooling By how water solutions

Halite, gypsum, calcite Leucite, olivine Quartz, feldspar, tourmaline, mica

Selenite, silver, gold, quartz

Where are mineral resources found? ● Earth’s crust is made of the rock-forming minerals

○ Less common minerals are not found in Earth’s crust, they are brought together in deposits■ An ore is a deposit of valuable minerals contained in rocks■ Ores are mined and the mineral is separated from the rock, like iron, lead, graphite, sulfur