Transcript Chap5_Minerals

Ch 5- Minerals
Minerals
Ch 5, p. 103
QOD- What is a mineral?
 Question set- #1-10 today. Show me when
you finish 1-10 and then keep in notebook.
 REMEMBER: LAB TOMORROW!
– Missing contracts
– Shoes & Lab Safety Rules
Sep 14
 QOD- What are the seven physical
properties used to identify minerals?
1. Review of Identifying Metals Lab
2. Video Clip- Minerals
3. Notes & Questions- ch 5 minerals
4. Keep the questions in your notebook
5. Test 4 – 5 Wednesday
Sep23 Earth Systems
 Test- chapters 4 & 5 is Thursday!
 Today– Ch 5 notes
 Tomorrow– Last day to turn in mineral projects
 Wednesday: Crystal Growing-!
– Bring 1 pound (2 cups) sugar
– Wear close toed shoes
 Thursday- test ch 4-5
Is it a Mineral?
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Is it inorganic?
Does it occur naturally?
Is it a crystalline solid?
Consistent chemical composition?
Must answer yes to all 4 questions for it to
be a mineral
10 Most common minerals
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Quartz
Calcite
Orthoclase
Dolomite
Plagioclase
Halite
Muscovite
 Gypsum
 Biotite
 Ferromagnesian
minerals
 These make up 90%
of Earth’s mass
Mineral Groups
 Silicates
– 96% of Earth’s crust
– Contains Si (silicon) and O(oxygen) quartz
– Can have other elements also
– Feldspar –
 Orthoclase if K (potassium),
 Plagioclase if Na (sodium) or Ca
(calcium)
– Ferromagnesian minerals – rich in Fe (iron)
Orthoclase - Lorenzenite
Plagioclase - Albite
Ferromagnesian - Olivine
• Mineral Groups
 Nonsilicate Minerals
– Do not contain
Si and O
 Can contain one or
the other, but not both
– Six groups
 Carbonates
 Native elements
 Halides
 Oxides
 Sulfates
 Sulfides
Carbonate - Calcite
Halide - Halite
Native Elements Gold
Oxides - Hematite
Sulfides - Galena
Sulfates - Gypsum
Crystalline Structure
 Crystal – atoms, ions, or molecules are
arranged in a regular, repeating pattern
 Silicate crystal structure
– Silicon – oxygen tetrahedron
– 1 Si with 4 O’s around it (illustrated in the book)
– Basic building block of silicates
– Can be connected 6 different ways
Silicate Tetrahedron
Crystalline Structure
 Nonsilicate crystals
– Diverse chemical composition leads to variety of
crystal structures
– Cubes, hexagonal prisms…
– Crystal structure influences physical properties
 Native elements are dense due to compact crystal
structure
Physical Properties
of Minerals
 Mineralogist
– Examine, analyze, and classify minerals
 Result from chemical composition and
crystal structure
 Can be useful in identifying minerals
Physical Properties
1) Color
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Not reliable for ID purposes (subjective)
Small amount of impurities can affect color
Weathered surfaces may hide color
Only look at fresh surfaces
Color
Physical Properties
2) Streak
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Color of mineral in powder form
Streak plate – unglazed ceramic tile
Streak color may differ from mineral color
Metallic minerals – darker streak
Nonmetallic minerals – lighter streak
Streak
Physical Properties
3) Luster
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Light reflected from mineral’s surface
Metallic luster – shiny surface
Nonmetallic luster
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Glassy
Waxy
Pearly
Brilliant
Dull / Earthy
Metallic Luster
Glassy Luster
Quartz
Waxy Luster
Variscite
Pearly Luster
Talc
Brilliant Luster
Diamond
Dull / Earthy Luster
Psilomelane
Physical Properties
4) Cleavage / Fracture
– Cleavage
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Splitting along specific lines of weakness
Forms smooth, flat surfaces
– Fracture
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Break unevenly into pieces
Forms curved, irregular surfaces
Conchoidal fractures – curved surface
Cleavage - Calcite
Fracture
Conchoidal
Fracture
Irregular
Physical Properties
5) Hardness
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Ability to resist scratching
Mohs Hardness Scale
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Scale of 1 to 10
1 = Talc
10 = Diamond
Glass is about a 5
Mohs Hardness Scale
Physical Properties
6) Crystal Shape
– 6 Basic shapes
– Certain minerals always form crystals with the
same shape
7) Density
– Ratio of mass to volume
– Can help identify minerals
Crystal Shapes
Physical Properties
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Fluorescence and phosphorescence
Chatoyancy and asterism
Double refraction
Magnetism
Radioactivity
Diamond fluorescence with ultraviolet light
Phosphorescence
– over time on a
watch face
Chatoyancy
Asterism
Double Refraction
Crystal Growing Lab- Wedn.
 Bring 1 pound (2 cups) sugar
 Wear close toed shoes