Rock Identification

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Rock Identification
Click Here to Learn more about a specific rock.
Click Here to take a practice Rock ID Test
Learn Your Rocks
Rock ID Practice Test
Quartz Sandstone
Obsidian
Garnet Mica Schist
http//www.mlms.logan.k12.ut.us/mlowe/PowerPoints
/RockIDPracticeA.ppt
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Learn Your Rocks
Select a rock to learn more about it.
Gneiss
Conglomerate
Granite
Obsidian
Garnet Mica Schist
Rhyolite
Pumice
Quartz Sandstone
Quartzite
Fossillferous Limestone
Breccia
Gabbro
Mica Schist
Coquina
Andisite
Rock Salt
Marble
Scoria
Diorite
Basalt
Chalk
Slate
Shale
Agate
Chert
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Rock Review Practice Test
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Gneiss
A banded or foliated rock usually made from some
type of granite. Color will vary considerably
based on the amount and kind of minerals found in
the original granitic rock.





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Metamorphic
Particle Size, Texture
Foliated, Crystalline
Mineral Composition
Amphibole, Feldspar, Quartz
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Obsidian
A black, banded, or spotted hard volcanic glass
that is formed by very rapid cooling of lava.
Historically, many different peoples have used
the glass rock to fashion sharp tools such as
knives and spear points.





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Igneous, Extrusive
Particle Size, Texture
Compact Glassy
Mineral Composition
Silica Rich
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Pumice
A light, porous, fibrous, glassy lava, used in
solid form as an abrasive and in powdered form as
a polish and an abrasive. Sometimes its density
is low enough that it will float in water.
Pumice is lava that had a lot of gases in it and
cooled quickly on the surface of the earth.





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Igneous, Extrusive
Particle Size, Texture
Compact, Fibrous, Glassy
Mineral Composition
Silica Rich
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Conglomerate
A rock consisting of heterogeneous pebbles and
gravel embeded in a cement made of clay, silt and
sand particles.





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Sedimentary
Particle Size, Texture
Gravel and smaller sized particles
Mineral Composition
Varied, heterogeneous mixture
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Garnet Mica Schist
A mica rich leafed foliated rock that is formed
under great heat and pressure. Garnet crystals
have developed on the rock as it was being
formed. The rock may be silvery white to
various shades of grey and exhibit yellow to
brown tones depending on the oxidation of the
various minerals in the rock sample.





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Metamorphic
Particle Size, Texture
Leaf like foliation
Mineral Composition
Muscovite and Garnet
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Quartz Sandstone
A rock formed by the consolidation and compaction
of generally rounded sand particles cemented
together by clay, silt, or silica particles. The
color will vary based on the trace elements
present in the quartz sand particles. The rock
may show color banding and cross-bedding
patterns.





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Sedimentary
Particle Size, Texture
Sand size, crystalline
Mineral Composition
Quartz
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Fossillferous Limestone
A common sedimentary rock consisting mostly of
calcium carbonate which contains fossils of
various fresh and or salt water shell fish. It
is used as a building stone, and in the
manufacture of lime, carbon dioxide, and cement.





Acid Test
Reacts with Acid
Scratch Test
Will not scratch glass
Rock Type
Sedimentary
Particle Size, Texture
Sand size, smooth
Mineral Composition
Calcite
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Quartzite
A rock formed by the metamorphism of quartz
sandstone. Quartz is a very hard mineral
composed of silica. Quartzite can be a wide
variety of colors depending on what elements are
present in small amounts. Quartzite is very
prevalent and is found worldwide.





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Metamorphic
Particle Size, Texture
Non-foliated, Crystalline
Mineral Composition
Quartz
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Granite
A common hard igneous rock consisting mostly of
quartz, orthoclase or microcline, and mica.
Granite is used for building and paving.





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Igneous, Intrusive
Particle Size, Texture
Course grained, Crystalline
Mineral Composition
Quartz, Potassium Feldspar
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Rhyolite
A volcanic rock similar to granite in composite
that cooled much more rapidly than granite that
usually exhibits flow lines. Color may vary.





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Igneous, Extrusive
Particle Size, Texture
Fine grained
Mineral Composition
Light color indicates a felsic composition
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Diorite
Any of various intermediate to dark granite
textured crystalline rocks rich in plagioclase.





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Igneous, Intrusive
Particle Size, Texture
Course grained Crystalline
Mineral Composition
Amphibole, Intermediate Feldspar
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Breccia
Rock composed of sharp angled fragments embedded
in a fine grained matrix of sand, silt, and clay
particles. The sharp edged rock generally are
from a talus slope.





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Sedimentary
Particle Size, Texture
Gravel size to smaller angular broken rock
Mineral Composition
Large variety
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Shale
A rock composed of fine grained layers of
sediment. Shale is often embedded with Fossils
of plant and animal material.





Acid Test
No Reaction
Scratch Test
Will not scratch glass
Rock Type
Sedimentary
Particle Size, Texture
Clay sized particles
Mineral Composition
Clay minerals
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Slate
A fine grained, grayish metamorphic rock that
splits into smooth surfaced layers. It has been
used for blackboards, roofing material and
paving stones. It is generally made of
metamorphosed shale. .





Acid Test
No Reaction
Scratch Test
Will not scratch glass
Rock Type
Metamorphic
Particle Size, Texture
Foliated, fairly smooth
Mineral Composition
Clay minerals
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(No Transcript)
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Basalt
A hard dense igneous rock composed chiefly of
plagioclase, pyroxene And olivine and often
having a glassy appearance.





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Igneous, Extrusive
Particle Size, Texture
Fine grained Crystalline
Mineral Composition
Amphibole, pyroxene Intermediate Feldspar
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Rock Salt
A rock containing mostly halite, table salt, as
its main constituent. The color of the rock salt
can vary depending on the trace mineral present
In the sample. This is an evaporite in that it
is the salt left after the salt has evaporated
from saltwater. It is very tasty.





Acid Test
No Reaction
Scratch Test
Will not scratch glass
Chemical Sedimentary, Evaporite
Rock Type
Particle Size, Texture
Solid mass of inter-grown crystals.
Mineral Composition
Halite, trace minerals
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Agate
A fine grained variety of quartz with colored
banding. The colored banding results from the
presence of various trace elements. Agates have
been cut and polished to use for jewelry for some
time.





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Chemical Sedimentary
Particle Size, Texture
Micro-crystalline
Mineral Composition
Quartz, Trace minerals
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Marble
A metamorphic rock formed from limestone or
dolomite. Irregular Coloring is often present
because of trace elements in the marble. Marble
is often used for sculpting and as a building
material.





Acid Test
Reacts with acid
Scratch Test
Will scratch glass
Rock Type
Metamorphic
Particle Size, Texture
Non-foliated Crystalline
Mineral Composition
Calcite, Trace Elements
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Mica Schist
Medium to course grained metamorphic rocks
composed of laminated often flaky parallel layers
of micaceous rock.





Acid Test
No Reaction
Scratch Test
Will not scratch glass
Rock Type
Metamorphic
Particle Size, Texture
Foliated
Mineral Composition
Muscovite, Biotite
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Coquina
Cream to pale brown, porous, poorly cemented
organic limestone composed
of marine or freshwater mollusk shells and shell
fragments.





Acid Test
Reacts with acid
Scratch Test
Will not scratch glass
Rock Type
Sedimentary, Organic
Particle Size, Texture
Gravel size and smaller shell material
Mineral Composition
Calcite, Calcium Carbonate
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Chalk
A soft compact calcite with varying amounts of
quartz, silica, feldspar, and other mineral
impurities. Chalk is generally grey-white to
yellow- White in color. It is derived chiefly
from fossil sea shells.





Acid Test
Reacts with acid
Scratch Test
Will not scratch glass
Rock Type
Sedimentary, Organic
Particle Size, Texture
Fine particles, very soft
Mineral Composition
Calcium Carbonate, Calcite, Trace minerals
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(No Transcript)
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Gabbro
A course grained igneous rock composed chiefly of
calcic plagioclase
and pyroxene





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Igneous, Intrusive
Particle Size, Texture
Course grained, Crystalline
Mineral Composition
Calcic plagioclase, pyroxene
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Chert
A siliceous rock of chalcedonic or opaline silica
occurring in limestone. Color may vary
considerably. White to grey to black sample will
probably be flint. Yellow green brown and red
will probably be Jasper.





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Sedimentary
Particle Size, Texture
Dense smooth Fine Particles
Mineral Composition
Chalcedonic, opaline silica, color varies
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Scoria
A volcanic rock having vesicular structure due to
the gases that are moving through the lava as it
cools and solidifies. Scoria has basaltic
composition. It can vary in color from dark grey
to black or dark brown to reddish rust.





Acid Test
No Reaction
Scratch Test
Will scratch glass
Rock Type
Igneous, Extrusive
Particle Size, Texture
Rough grained, fine crystalline
Mineral Composition
Plagioclase feldspar, pyroxine
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Andesite
A A white to grey igneous rock that usually forms
on the surface in lava flows (extrusive) or
sometimes as dikes and sills (intrusive) under.






Acid Test
No Reaction
Scratch Test
Will scratch glass
Igneous, Extrusive or Dikes sills Intrusive
Rock Type
Particle Size, Texture
Fine grained, Crystalline
Plagioclase, Feldspar, amphibole, Pyroxene,
Biotite
Mineral Composition
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