Mineral and Rocks Unit

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Mineral and Rocks Unit

• Lessons Included
• Minerals
• Igneous Rocks
• Sedimentary Rocks
• Metamorphic Rocks

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Minerals
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Table of Contents

• Minerals Defined
• Mineraloids
• Industrial Minerals
• Biochemical Minerals
• Characteristics of Minerals
• Crust Composition
• Examples of Various Mineral Compositions
• Crystalline Form

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1. Minerals Defined

• a. A mineral is the basic material that makes
  up the earths crust and has the following
  characteristics
• Naturally occurring
• Inorganic
• Has a fixed chemical composition
• Has an orderly internal arrangement of atoms.

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1. Minerals

1. Mineraloids-Lack crystal structure (Examples
   include rare gemstones)
2. Industrial Minerals- Used for manufacture of
   physical materials.
3. Biochemical Minerals- Can be manufactured by
   organisms (Example Aragonite-Made by clams to
   produce their shells)

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2. Characteristics of Minerals

• Naturally Occurring- Formed as a result of
  natural processes in or on the earth
• Inorganic- Came from things that were never
  alive.
• Fixed Chemical Composition- Use of a chemical
  formula or symbol to represent what mineral is
  made of.
• 1. Some minerals found as pure elements (Cu, Ag),
  most are found as compounds (Calcite(CaCO3),
  Quartz(SiO2).

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3. Composition of Crust
98 of the crust is made of just 8 elements,
even though there are over 100 known elements (
Pg 11 of ESRT)
Element by Mass
Oxygen 46.40
Silicon 28.15
Aluminum 8.23
Iron 5.63
Calcium 4.15
Sodium 2.36
Magnesium 2.33
Potassium 2.09
Nitrogen
Hydrogen
Other 0.66
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Composition of Crust
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4. Examples of Various Mineral Compositions
Mineral Chemical Name Chemical Formula
Calcite Calcium Carbonate CaCO3
Galena Lead Sulfide PbS
Gypsum Calcium Sulfate-Water CaSO2 2H2O
Olivine Magnesium Silicate Mg2SiO4
K-Feldspar Potassium aluminum silicate KAlSi3O8
Pyrite Iron Sulfide FeS2
Quartz Silicon dioxide SiO2
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Pictures of Minerals
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5. Crystalline Form

1. Atoms or molecules of a mineral are the same
   throughout that mineral
2. There is a definite repeating pattern in
   minerals, if pattern is large enough to be seen
   it is called a crystal.
3. Internal structure determines outside structure.

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5. Crystalline Form Cont.

• d. The shape of the minerals crystals is a
  result of its atomic arrangement

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5. Crystalline Form

1. Atoms or molecules of a mineral are the same
   throughout that mineral
2. There is a definite repeating pattern in
   minerals, if pattern is large enough to be seen
   it is called a crystal.
3. Internal structure determines outside structure.

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5. Crystalline Form Cont.

• d. The shape of the minerals crystals is a
  result of its atomic arrangement

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Use your Earth Science Reference Tables (ESRT)
page 16 when identifying an unknown mineral!
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6. Identifying Minerals

• There have been over 2000 minerals identified.
• They can be classified by both physical and
  chemical properties.

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7. How to Identify Minerals

• Color- First property usually observed.
• Very unreliable way to identify minerals
• Many minerals come in a variety of colors
  (Quartz)
• Some minerals have same color (Pyrite (FeS2) and
  Gold (Au))
• Due to impurities

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The many colors of Fluorite
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7. Identifying Minerals

• Luster- The way a mineral reflects light from
  its surface.
• Nonmetallic-Glassy, brilliant, greasy, oily,
  waxy, silky or earthly.
• Metallic- Has metallic properties

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7. Identifying Minerals

• Streak- This is the color of the fine powder left
  when a mineral is scratched against an unglazed
  ceramic tile.
• Even if color of mineral changes (Quartz) the
  streak is always the same. (This is a very
  reliable way to identify minerals)

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7. Identifying Minerals

• Hardness- The ability for a mineral to resist
  being scratched.
• The hardness of a mineral is usually stated in
  terms of Mohs scale of hardness
• A harder material can always scratch a softer
  material but a softer one cant scratch a harder
  one.
• HANDOUT

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7. Identifying Minerals

• Cleavage- The tendency of a mineral to break
  parallel to atomic planes in its crystalline
  structure.
• Ex. Mica- Breaks in parallel layers

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7. Identifying Minerals

• Fracture- When minerals break unevenly because
  all planes are equally strong in all directions.
• Conchoidal- Smooth, curved break that looks like
  a shell
• Fibrous or splintery- Fibers
• Hackley- Jagged sharp edges (Native Metals)
• Uneven

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Mica
Halite
Galena, Pyrite
Calcite
Fluorite
Feldspar
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8. Alternate ways to Identify Minerals

1. Specific Gravity- This is a ratio off the density
   of a mineral compared to the density of water.
   (NO UNITS)
2. Chemical Tests- Use of HCl tests for calcium
   carbonate, if mineral contains it will bubble or
   effervesce. (Calcite, Dolomite)

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8. Alternate ways to identify Minerals

• c. Magnetism- Minerals that contain iron, copper
  or nickel will attract a magnet.

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9. Major Mineral Groups

1. Silicates- One ion of silicon is attached to 4
   ions of oxygen in the shape of a tetrahedron.
   Bonds are strong.
2. Sulfides- When 1 or more sulfur ions combine with
   a metallic ion (PbS, FeS, ZnS)

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9. Major Mineral Groups

• Oxides-Compounds in which Oxygen is joined with
  ions of other elements, usually metals.
  (Fe2O3,FeO).
• Carbonates and Sulfates- Minerals contain Oxygen,
  the oxygen ion join with other ions to form
  polyatomic ion
• Carbonate ion (CO3)-2
• Sulfate ion (SO4)-2
• HANDOUT

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8. Alternate ways to Identify Minerals

1. Specific Gravity- This is a ratio off the density
   of a mineral compared to the density of water.
   (NO UNITS)
2. Chemical Tests- Use of HCl tests for calcium
   carbonate, if mineral contains it will bubble or
   effervesce. (Calcite, Dolomite)

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8. Alternate ways to identify Minerals

• c. Magnetism- Minerals that contain iron, copper
  or nickel will attract a magnet.

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9. Major Mineral Groups

1. Silicates- One ion of silicon is attached to 4
   ions of oxygen in the shape of a tetrahedron.
   Bonds are strong.
2. Sulfides- When 1 or more sulfur ions combine with
   a metallic ion (PbS, FeS, ZnS)

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9. Major Mineral Groups

• Oxides-Compounds in which Oxygen is joined with
  ions of other elements, usually metals.
  (Fe2O3,FeO).
• Carbonates and Sulfates- Minerals contain Oxygen,
  the oxygen ion join with other ions to form
  polyatomic ion
• Carbonate ion (CO3)-2
• Sulfate ion (SO4)-2
• HANDOUT

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Remember

• Your ESRT pg 16 lists all the mineral information
  you will need to identify an unknown mineral
  sample!

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Igneous Rocks
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Table of Contents

• Formation of Igneous Rocks
• Characteristics of Igneous Rocks
• Texture
• Mineral Composition
• Textures of Igneous Rocks
• Intrusive
• Pegmatic (Very coarse grained)
• Phaneritic (Coarse grained)
• Extrusive
• Aphanitic (Fine Grained)
• Glassy
• Vesicular (Gas Bubbles)
• Pyroclastic (particles from volcano)
• Intrusive and Extrusive
• Porphyritic
• Mineral Composition
• Felsic
• Mafic
• How to Identify Igneous Rocks

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Igneous Rock ID ChartPage 6 of ESRT
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1. Formation of Igneous Rocks

• Form as the result of cooling or solidification
  of Magma.
• LIQUID HOT MAGMA
• Mixture of hot liquid rock, gases and crystals
• Less dense than surrounding rock so it moves
  upward
• Magma that reaches surface (lava) erupts and
  solidifies- Extrusive IR
• Magma that cools underground-Intrusive IR

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2. Characteristics of Igneous Rocks

• Texture- The size, shape and arrangement of the
  mineral crystals or grains of rocks.
• Slow cooling- Large Crystals, intrusively formed
• Rapid cooling- Small Crystals, extrusively
  formed
• b. Mineral Composition- Minerals that make up
  the rock. Made of a combination of 8. (Muscovite
  and biotite mica, Quartz, Potassium and
  Plagioclase Feldspar, Amphibole, Pyroxene and
  Olivine)

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Pictures of 8 minerals that comprise Igneous Rocks
Felsic
Mafic
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3. Textures of Igneous Rocks

• a. Intrusive (Plutonic) Magma trapped underground
  and solidifies. As a result of slow cooling large
  crystals are able to form.

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3a. Intrusive Igneous Rocks

1. Pegmatic (Very Coarse)- Crystals gt10mm, very slow
   cooling. (Pegmatite)
2. Phaneritic (Coarse) Crystals 1-10mm, slow
   cooling. Granite and (Gabbro)

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3. Textures of Igneous Rocks

• b. Extrusive (Volcanic) Formed from the rapid
  cooling of lava result the rock has a very fine
  structure and sometimes none at all

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3b. Extrusive Igneous Rocks

1. Aphanitic (fine texture) crystals lt1mm.(Rhyolite)
2. Glassy- Result of rapid cooling no visible
   crystals at all. (Obsidian)
3. Vesicular- Rapid cooling of gas filled lava, has
   holes. (Pumice)
4. Pyroclastic- Particles emitted from volcanoes.

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3c. Intrusive and Extrusive

• 1. Porphyritic- Has both small and large
  crystals. Result of cooling underground- Large
  Crystals (Phenocrysts) and rapid cooling above
  ground (Groundmass or matrix)

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4. Mineral Composition

1. Felsic Group- Igneous rock contains mostly
   Quartz, Potassium and Plagioclase Feldspar, tend
   to be light colored and low density.
2. Mafic Group- Igneous rock contains mostly
   Olivine, pyroxene, and amphibole, tend to be dark
   colored and higher in density.

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5. How to Identify Igneous Rocks

• Identify rocks color index
• Light Colored- Felsic
• Dark Colored- Mafic
• Identify mineral composition by Color index.
• Identify Rocks Texture
• Intrusive- large crystals
• Extrusive- Small or no crystals or gas bubbles.

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Sedimentary Rocks
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Table of Contents

• Sediments
• Sedimentary Rocks Defined
• Formation of Sedimentary Rocks
• 3 Types of Sedimentary Rocks
• a. Clastic
• Grain Size
• Grain Shape
• Grain Arrangement
• Chemical
• Organic
• How to Classify Sedimentary Rocks

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1. Sediments

• These are loose grains and chemical residues of
  Earth materials
• 1. Formed by
• Chemical and Physical weathering

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2. Sedimentary Rocks Defined

• a.These are rocks that form when sediments are
  compressed together or otherwise hardened , or
  when masses of inter-grown mineral crystals
  precipitate from water.

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3. Formation of Sedimentary Rocks

• Lithification- The hardening of sediment to
  produce rock. Usually occurs in layers.
• Compaction- Increased pressure from overlying
  sediment
• Cementation- Binding together of sediments
• Precipitation- When sea water evaporates leave
  aggregates of intergrown and interlocking
  crystals

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Sedimentary Rock Identification Chart (Page 7
ESRT)
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4. 3 types of sedimentary rocks

• a.CLASTIC formed from fragments of other rocks
• Sandstone, Conglomerate
• b.CHEMICAL formed from the mineral precipitates
  of evaporated seawater
• Rock Salt
• c.ORGANIC formed from the remains of plants
  animals with rock fragments
• Coal, Fossil Limestone

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4a. CLASTIC

• Formed when rock fragments sediment are carried
  deposited by WIND, GLACIERS, RUNNING WATER
• Sediments are DEPOSITED, then COMPACTED finally
  CEMENTED together

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4a1. Grain Sizes of Clastic Sedimentary Rocks

• Based on Wentworth scale
• Gravel- Grains gt2mm (Boulders, pebbles)
• Sand- Grains 1/16mm to 2mm (Sandbox)
• Silt- 1/256mm to 1/16mm (too small to see)
• Clay- lt1/256mm (too small to see)

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Pictures of Rocks With Specific Grain Size
Grain Size Sediment Rock name
Larger than 2mm Gravel Conglomerate
2mm to 0.06mm Sand Sandstone
0.06 to 0.002mm Silt Siltstone
Smaller than 0.002mm Clay Shale
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4a2. Grain Shape of Clastic Sedimentary Rocks

• Grain Shape- Sediments can be transported over a
  great distance by wind water and ice.
• Angular- Transported short distance
• Rounded- Traveled longer distance
• Well Rounded- Traveled very long distance.

Well Rounded--------------------------------------
--------------------Angular
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4a3. Grain Arrangement of Clastic Sedimentary
Rocks

• Grain Arrangements- Different velocities of wind
  and water currents capable of transporting and
  separating different densities and sizes of
  sediments
• Poorly Sorted- Many different sizes
• Well Sorted- All grains same size

Poorly Sorted-------------------------------------
-----------Well Sorted
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Stream Velocity versus Particle Size
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4b. CHEMICAL

• Formed when dissolved minerals in seawater are
  deposited (seawater evaporates, leaving the
  minerals behind)
• Usually old swamps, seas, or lakes evaporate
• Also known as CRYSTALLINE because of the fine
  crystals
• Limestone, Rock Salt, Rock Gypsum (sheetrock)

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Salt Mines - Rock Salt is being formed as the
salt water evaporates from the sea.
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Devils Golf Course millions of years ago
this was a sea of salt water. It has been
evaporating over time
and has formed pockets of chemical limestone,
rock salt, and rock gypsum!
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4c. ORGANIC

• Formed from the remains of plants animals that
  are compacted
• Fossil Limestone formed when shell remains of
  marine organisms are cemented in fragments
• Shells are made of CALCITE which reacts with acid
  and is a natural cement

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Brachiopod fossils in limestone
Imprint of a leaf
Trilobite fossils over 250 MILLION years old!!!
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If peat at the bottom of a swamp is buried
compressed, coal may form
Coal note distinct layering of peat
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5. How to Classify Sedimentary Rocks

• Determine rocks general composition (Clastic,
  Organic or Chemical)
• Describe rocks texture
• Grain Size
• Grain Shape
• Grain Arrangement
• Determine rocks name by using flow chart

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Metamorphic Rocks
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Table of Contents

• Metamorphic Rocks Defined
• Ways Metamorphic Rocks form.
• Heat
• Pressure
• Chemical Activity
• Types of Metamorphism
• Regional
• Contact
• Textures of Metamorphic Rocks
• Foliated
• Non-Foliated
• How to identify a Metamorphic rock using the
  handout.

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1. Metamorphic Rocks Defined

1. Metamorphic- From Greek meaning of changed
   form.
2. Metamorphic Rocks are rocks changed from one form
   to another by heat, pressure or the action of hot
   fluids.

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1. Metamorphic Rocks Defined

• c.Every metamorphic rock has a parent rock in
  which it can come from it can be
• Igneous, Sedimentary or even metamorphic.
• d. Examples
• Conglomerate? Metaconglomerate
• Sandstone? Quartzite
• Limestone? Marble

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2. Ways Metamorphic Rocks Form

• Heat-
• Expansion? atoms move apart? bonds stretched and
  weakened
• Extreme heat? Result of deep burial? Magma
  formation? New minerals made
• Pressure-
• Compaction? atoms move closer? stress causes
  bonds to break

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3. Types of Metamorphism

• Contact- Occurs locally, over short periods of
  time and adjacent to Igneous Intrusions.
• Intensity is greatest at contact between parent
  rock and intrusive magma. Intensity decreases
  with increasing distance.
• (High Grade)-Gneiss, Schist, phyllite, Slate-(Low
  Grade)? SHALE (SR)

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3. Types of Metamorphism

• Regional-Occurs over large areas, accompanied by
  folding rock layers and mountain building.
• Causes- Large igneous intrusions that form and
  cool over long periods.

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4. Textures of Metamorphic Rocks

• Two main groups Foliated or Non foliated
• Foliated- Mineral Alignment Mineral are in layers
  usually Mica
• Banding- Alternating layers of different colored
  minerals (Distorted by heat and pressure)

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More foliation slate phyllite
Foliation note the scratches in the rock
this is mineral alignment!
Excellent example of banding distortion this
is GNEISS ?
Banding mica schist
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Metamorphic mountains formed from regional
metamorphism
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Alaskas Copper Mountain contact metamorphism
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4a. Foliated Metamorphic Rock Texture

1. Slaty rock Cleavage- Very flat, parallel, closely
   spaced shear planes. (Slate)
2. Phyllite Texture- Wavy or wrinkled foliation-
   Rock has metallic luster. (Phyllite)

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4a. Foliated Metamorphic Rock Texture

• 3. Schistosity- Scaly or glittery layering of
  platy minerals (Schist)
• 4. Gneissic Banding- Alternating layers or
  lenses of light and dark medium to coarse grained
  minerals. (Quartz, Feldspar-Light bands,
  Ferromagnesium Dark bands

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4. Textures of Metamorphic Rocks

• Nonfoliated- No obvious layering
• Crystalline- Medium to coarse grained of
  intergrown, equal sized visible crystals (Marble)
• Microcrystalline- Fine grained intergrown
  crystals. (Hornfels)
• Sandy- Medium to coarse grained fused sand sized
  grains. (Quartzite)
• Glassy- No visible grains. (Anthracite coal)

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5. How to Identify Metamorphic Rocks

1. Determine if rock is foliated or non-foliated and
   what other textual features are present.
2. List minerals in order of increasing abundance.
3. Determine Metamorphic rock name
4. Find out what parent rock is

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