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Aim: How do minerals form?

Do Now:
1) What is the smallest thing on Earth?

2) What is the largest thing that you know of?

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Objectives:

How do minerals form?

What are the properties of minerals?

How do we identify minerals?

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Atoms

Atoms – basic building blocks for all earth materials; consist of 3 basic components: protons, neutrons, electrons

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Atoms combine to form Elements

Elements – fundamental component that can not be broken down into other substances by ordinary chemical processes

Elements combine to form minerals

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General Facts About Minerals

2,000 + minerals have been identified

A few are “native elements” -- made of only one element, such as sulfur, gold. copper, and graphite (carbon)
Most are compounds, especially the silicate group (Si, O).
Other important groups are oxides, carbonates, and sulfides.

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Gold (Au)

Silver (Ag)

Platinum (Pt)

Diamond (C)

Graphite (C)

Sulfur (S)

Copper (Cu)

MINERALS

NATIVE ELEMENTS

Copper

Silver

Gold

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Mineral Criteria

1. Crystalline solid – atoms have specific arrangement or crystal structure

2. Naturally occurring – not manufactured

3. Have a definite chemical composition – may be a single element or combination

4. Inorganic – minerals not made by living things (organic)

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MINERAL FORMATION

CRYSTALLIZE FROM MAGMA or LAVA solidification of liquid magma/lava to solid with a definite internal arrangement of atoms into a regular repeating pattern

PRECIPITATE FROM SOLUTION dissolved minerals come out of solution (water) to form solids

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Minerals are identified by their Physical Properties

Crystal Form – determines physical properties
Color
Streak
Luster – metallic, non-metallic
Hardness – Mohs Hardness Scale (1-10)
Cleavage
Fracture
Acid Test for carbonate minerals

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A mineral’s physical properties are controlled by its internal arrangement of atoms

regularly repeating, orderly pattern

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The most common crystalline structure

Silica-oxygen tetrahedron – basic building block for silicate minerals

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Silica tetrahedron combine several different ways

Five major types of silicate minerals based on their structure

Isolated tetrahedron
Single chain

C) Double chains

D) Sheet silicates

E) 3-D framework silicates

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Minerals can have the same chemical composition (Carbon) but different physical properties because of their crystal structure

Diamond Graphite

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Page 220-222

Define

Color
Streak
Hardness
Luster
Density
Cleavage / Fracture
Crystal structure

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Exit Slip

What are the 2 ways that minerals form?

What is an atom?

What is a compound?

Why do compounds give minerals their shape?

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Class Flow

Students get binders out.
Complete labs
Density Demo
Write observations in notes
Take notes on power point
Create foldable with properties of minerals
Pass minerals around check whether cleavage or fracture.
Hand in mineral paper

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Learning Target #5: What are the properties of minerals?

Essential Question: What will I look for when I identify a mineral?

Do Now: Complete your labs.

The parts you have missed on the density lab have been highlighted in red.

There will be 10 points taken off your grade each time you hand in an incomplete lab.

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Let’s wrap up the lab.

WHAT REALLY IS DENSITY???

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Minerals

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Which diamond is real?

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COLOR

Color is not usually a definitive property of a mineral.
Some minerals have characteristics colors
Others vary due to chemical differences or impurities (atoms mixed inside the main elements)
However most minerals have a variety of colors.

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Some Colors of Quartz

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STREAK

For opaque minerals, if you rub the sample across a streak plate, it will leave a colored powder. This streak is distinctive for minerals and is used to identify minerals.

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Varieties of Hematite – all same color streak

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HARDNESS – Mineral’s resistance to scratching or abrasion. Minerals with higher numbers will scratch minerals below

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LUSTER – Does this look like it could be made from a hard metal?

Describes how light reflects off the surface

Categories: Metallic or Non-metallic

Metallic – luster of metal – shines like a hard metal

(light does not penetrate)

Many non-metallic minerals are SHINY because they are transparent or semi-transparent

Non-metallic: vitreous or glassy; silky; pearly; greasy; waxy, dull; earthy

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Examples of metallic luster

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Pyrite (FeS₂)

Galena (PbS)

More Examples of Metallic Luster

PYRITE

GALENA

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Example of non-metallic luster

Vitreous--quartz

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Example of non-metallic luster

Silky--example plagioclase feldspar

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Non-metallic and metallic luster – earthy hematite – metallic hematite

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Cleavage and Fracture

Some minerals split along flat surfaces (called cleavage planes) when struck hard--this is called mineral cleavage
Other minerals break unevenly along rough or curved surfaces--this is called fracture
A few minerals have both cleavage and fracture ( mica )

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Cleavage – due to weak bonds in the crystal structure

FLUORITE

HALITE

Halite (NaCl)

Fluorite (CaF₂)

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Cleavage

BIOTITE

MUSCOVITE

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Rose Quartz – Conchoidal Fracture

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Conchoidal Fracture - Quartz

Obsidian

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Cleavage or Fracture?

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lCleavage or Fracture?

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ClCleavage or Fracture?

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