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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