1 Rocks and Minerals GOLD! (before processing) Just what are they?

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Rocks and Minerals

GOLD!(before processing)

Just what are they?

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•Mineral: A naturally created•crystalline solid •that was never alive: inorganic•with distinct properties

Opal!(Hydrous quartz)

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•Rocks : any naturally formed solid that is part of Earth, made up of one or more minerals. •All minerals are rocks but•not all rocks are minerals•EX: Coal is not a mineral

because it’s made of ancient plant material but it is a rock!

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Where do rocks and minerals come from?

• Inside of and on the Earth • They make up the solid

surface of the Earth called the • lithosphere

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What are rocks and minerals used for?• Write down 3 things you

think contain or use minerals

• Pencils, jewelry, computers, tile, pipes, insulation, dishes, glass, makeup, toothpaste, roofing, tires, rubber, magnets, paint, cans, batteries, cars mouthwash, glue, medicine, , solder, fuel, fertilizer, explosives, photography, plastic, false teeth, catlitter, silverware, drywall, radioactive spill cleanup

• You get the idea? • And oh yeah…

• 95% of all manmade things use minerals!• we need minerals to live!

•Drywall or “sheetrock” is made of the fire resistant mineral: Gypsum

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Mineral Composition•Minerals are composed of

elements and combinations of elements called• compounds•MOST of the Earth’s crust is

only made up of a few elements.

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DO NOW:• Turn to page 11 in your reference

tables •What are the 2 most

common elements in Earth’s Crust?•Oxygen and Silicon• Minerals formed from these

elements are called silicates

sound familiar?(non toxic . NOT with dopant cobalt)

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Turn to page 16 in your reference tables

What very common mineral has a composition of Silicon (Si) and Oxygen (0)

QUARTZ!

DO NOW:

More varieties of QUARTZ!

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•There are ~ 4 thousand minerals!•What can we do to separate and classify each mineral?•What characteristics can we use???

Time to Classify…

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1.Using observations come up with 10 ways to classify the samples given to you

2.Break up into groups

3.Record your results on one page to be turned in with your names

Classification Assignment

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Properties of Minerals• Common ways to classify

minerals. 1. Hardness: • Found by scratching

minerals of unknown hardness with minerals of KNOWN hardness (1812 Fredrich. Mohs)

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Softest1. Talc 2. Gypsum 3. Calcite 4. Fluorite 5. Apatite

6. Feldspar 7. Quartz 8. Topaz 9. Corundum 10. Diamond

Hardest

Moh’s Scale of Hardness

Many of the harder ones

are used as gemstones!

(they resist scratching)

An Uncut DiamondPowdered diamond

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Properties of Minerals2. Color: Light Colors (tan pink white)

often contain aluminum and silica.

Dark Colors often contain iron, magnesium or calcium

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Color is not a good ID characteristic to use aloneWHY NOT?

Many different minerals can have the same color!

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Properties of Minerals3. Streak: Color of a mineral

when powdered on a streak plate

•While a minerals color may

change

the streak color is unique (and

usually stays the same!!)

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Properties of Minerals4. Cleavage or Fracture: Property

of a mineral to split apart into neat smooth planes (cleavage) or to break into uneven pieces like glass (fracture)

cleavagefracture

Cleavage or fracture?Cleavage or fracture?Cleavage or fracture?Cleavage or fracture?

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The main reason minerals have different properties is due to their different atomic structures

SALTNaCl crystals

Carbon in sheets…

Carbon bonded equally in every direction

8 Allotropes of carbon

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•This minerals’ atoms are bonded in loose sheets, •So the mineral itself has•Sheet (Basal) Cleavage

Biotite mica

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Properties of Minerals5. Crystal Shape: If a crystal

has grown large enough, you can see different crystal

shapes based on what it’s atomic structure is

HexagonalQuartz

20Hexagonal StructureBeryl aka (Emerald)

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Atomic Structure•A mineral’s atomic (crystal)

structure determines it’s physical properties. •EX.•Cleavage (or Fracture)•Crystal shape•Hardness…etc.

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Crystal Structure•Different minerals exhibit

different crystal shapes• It depends on what elements

are present in the magma they form from.•Because some elements are

more likely to form bonds than others (chem. 101)

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Crystal Structure• If given enough time to grow

the crystal structure will become visible to the naked eye•Often a crystal will run out

of room or material or cool too fast • and remain somewhat smallEvaporite Gypsum in Mexico Crystal Cave

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Crystal Structure of Silicates

SiliconTetrahedron

The basic building block of silicates.How many sides?

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Single Chain Silicates

•The atomic structure is long chains, so given time the mineral’s form appears aslong chains or “fibers”

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26Splinter/Fibrous fracture

So due to it’s atomic structure this mineral’s physical form has

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Properties of Minerals6. Luster: Describes how a

mineral reflects (or doesn’t reflect) light

• EX: Metallic, Non-metallic

Chatoyancy

Shiny

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Properties of Minerals7. Other:• Radioactivity• Taste (like Halite:salt!)• Fluorescence (glows in

Ultraviolet light)• Smell like many sulfur

containing minerals!

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3 Methods of Mineral Formation• 1) From cooling and

solidifying magma (lava)• 2) As a precipitate from a

liquid; (like when sea water evaporates leaving salt!)• 3) From a solid TO another

solid. This takes a long time!

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Properties of Minerals worksheet then Lab

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Lets see what basic crystals look like

Mineral Crystals Lab