Introduction to Minerals

Objectives What are minerals? What characteristics do all minerals share? What roles have minerals played in our civilization? Where do minerals come from and what are the processes by which minerals form? What are the major groups of minerals?

What are minerals? atoms. Minerals are a type of matter and we know that all matter is made of? But more specifically, a minerals must meet five criteria to be called a mineral… atoms.

SOLID Characteristic #1 All Minerals are… Which of the following could be a mineral?

Characteristic #2 Inorganic= were never alive All minerals are Which of the following could be a mineral? Inorganic- was never alive Organic- is currently alive

Characteristic #3 All minerals occur naturally. If that is true, which of the following is not made of minerals?

Characteristic #4 All minerals have a definite chemical composition. This means that in each individual mineral, certain types of atoms will come together (bond) in certain ways Ex. this is similar to how 2 hydrogen's and one oxygen come together to form the most important molecule on Earth! O H H

Characteristic #5 The atoms in minerals are arranged into orderly structures called crystals. Cubic Tetragonal Orthorhombic Hexagonal

Why are minerals important to learn about? A huge portion of Earth is made of minerals. Most rocks are a combination of minerals. Minerals provide nutrients to living things (like us) that allow us to live and thrive. Many of the things we use every day are manufactured using minerals. Can you think of any examples?

***You should see lots of different minerals in every single rock Minerals and Rocks Coal Gneiss Scoria Rocks are combinations of minerals Minerals are individual crystals of all the same stuff ***You should see lots of different minerals in every single rock

Examples: Amethyst Calcite Garnet Galena Gold Pyrite ***Notice how each is one single type of crystal! Amethyst Calcite Garnet Galena Gold Pyrite

Where do minerals come from? Mineral crystals can form in two ways: From stuff dissolved in liquids (Evaporation & Hot Water) From Cooling Magma & Lava

Minerals & Crystals from Magma & Lava Extrusive Cooling: Lava cools Fast (Short Time = Small Crystals) Minerals form from hot magma as it cools inside the crust, or as lava hardens on the surface. When these liquids cool to a solid state, they form crystals. Size of the crystal depends on time it takes to cool down. Intrusive Cooling: Magma cools slowly (Long Time = Large Crystals)

individual crystals in Rhyolite Minerals Crystal Size When the hot material cools fast, it has smaller crystal size. When it cools slowly, it has large crystals. Granite You can see individual crystals in Granite =cooled slowly Rhyolite You can’t see many individual crystals in Rhyolite =cooled very fast

Minerals formed by Evaporation Some minerals form when solutions/mixtures evaporate: When water evaporates, it leaves behind the stuff that’s dissolved in it. Longer it takes to evaporate, the larger the crystal. i.e. salt & water – ocean, Halite, Gypsum, Calcite. **All the white stuff = salt mineral crystals that formed when the water of this lake evaporated. The mineral material was left behind

These salt crystals formed from salt water because as the water evaporated, the salt wasn’t dissolved anymore. So the chemical energy in salt takes over and crystals form.

3,000 minerals exist on Earth Only around 20 are considered common These minerals form rocks 10 of these make up 90% of Earth’s crust. Quartz, orthoclase, Plagioclase, Muscovite, Biotite, Calcite, Dolomite, Halite, Gypsum, and Olivine/Pyroxene/Amphiboles.

Basic Properties Used to Identify: Color Cleavage Hardness Streak Luster Density Crystal Shape

A black light really brings it out! Special Properties Some minerals display strange properties. These can include: Magnetism, fluorescence, and reactivity. Fizzing! These minerals glow in the dark. A black light really brings it out! The minerals in this rock react with acid The particles of minerals of this rock act like magnets

Rocks are made from Minerals Rocks are nothing more than a mixture of different mineral crystals. ***All three minerals are combined in a Granite rock Granite Quartz + Biotite + Feldspar = (mineral) (mineral) (mineral) (Rock) This is Continental Crust

Rocks are made from Minerals ***Both minerals combined make Basalt Pyroxene + Olivine = Basalt This is Oceanic Crust (mineral) (mineral) (rock)

Two Main Groups of Minerals Silicate Minerals 96% of Earth’s crust Composed of silicon (Si) and oxygen (O) Quartz is pure Si and O, others contain other elements as well. Non-Silicate Minerals 4% of Earth’s crust Includes: Carbonates, Halides, Native elements, Oxides, Sulfates, and Sulfides.

Chemical composition Native elements Gold, Silver, Sulfur Au, Ag, S Pyrite, Galena FeS, PbS Sulfides Hematite, Magnetite Fe2O3, Fe3O4 Oxides SiO2 KAl2(AlSi3O10)(OH,F,Cl)2 KAlSi3O8 Quartz, Mica, Feldspar Silicates

Silic- is for Silicon (s) Silicates Silic- is for Silicon (s) -ate is a suffix for “oxide “ Silicates are “oxides of silicon” Look at the reference table and calculate the weight of silicon and oxygen.

Silicates Mica Quartz Can you find the “silica” ? SiO2 KAl2(AlSi3O10)(OH,F,Cl)2 Can you find the “silica” ?

Silica Structure 4 oxygen atoms for every 1 silicon atom

Amphibole (Hornblende) Complexity Temp. Olivine Pyroxenes (Augite) Amphibole (Hornblende) Micas Feldspar, Quartz

How can 2 minerals with the same composition be so different? Graphite Diamond Chemical formula: C Chemical formula: C How can 2 minerals with the same composition be so different?

“Internal Arrangement of Atoms” controls most physical properties! What’s the point here? “Internal Arrangement of Atoms” controls most physical properties!

Review of Concepts: 1. Minerals can be identified by examining….. Physical Properties, including…. Luster, Hardness, Cleavage, Color, Streak, Density…. 2. Minerals are classified according to their….. Chemical Composition, including groups like…. Native Elements, Sulfides, Oxides, and the all important SILICATES 3. The “Basic Building Block” of the Silicate Minerals is…..

Review of Concepts: (continued) 4. The physical properties of minerals are generally controlled by….. Crystalline Structure…. …or the “orderly internal arrangement of the atoms”! What do graphite and diamond have in common?…… Identical Chemical Composition…. What accounts for the differences between graphite and diamond? ….the “orderly internal arrangement of the atoms!