Download Rocks and Minerals

Gary Vorwald
NYS Rock & Mineral Supervisor
Paul J. Gelinas JHS
[email protected]
Event Description
 Participants will demonstrate
their knowledge of rocks and
minerals in this station-based
event.
 A team of up to 2
 Approximate time: 40 – 50
Minutes
Event Parameters
 Each team may bring:
 one magnifying glass
 One 3-ring binder (1 inch) containing
information in any form from any
source
 Materials MUST be 3-hole punched
and inserted into the rings (sheet
protectors allowed)
The Competition
 Station Event: 15-24 stations with
samples & questions
 Equal time intervals will be
allotted for each station.
 When the signal is given,
participants will begin work at
their initial station.
Participants may not move to the
next station until prompted to do
so, may not skip stations, nor
return to any previously-visited
station
Mineral and Rock Stations
The Competition
 HCl will not be provided, nor may it be brought to, or be
used during the competition.
 Written descriptions as to how a specimen might react
were it to be tested with HCl may be provided.
The Competition
 Identification will be limited to specimens appearing on
the Official Science Olympiad Rock and Mineral List
(see www.soinc.org)
 Other rocks or minerals may be used to illustrate key
concepts.
 Tournament Directors may include up to five additional
specimens important to their own state.
 If additional specimens are to be included, all teams must
be notified no later than 3 weeks prior to the competition.
2017 Rock & Mineral List
 Available at: https://www. soinc.org
 Students should place list in front of notebook
 Minerals are organized by mineral family
 Consists of:
 59 Minerals
 7 Metamorphic Rocks
 10 Igneous Rocks
 17 Sedimentary Rocks (or varieties)
Native Elements
16. Copper
18. Diamond
25. Gold
26. Graphite
50. Silver
54. Sulfur
Sulfides
12. Bornite
15. Chalcopyrite
23. Galena
40. Pyrite
52. Sphalerite
Halides
22. Fluorite
30. Halite
Oxides / Hydroxides
8. Bauxite
17. Corundum
24. Goethite/
Limonite
Minerals
Silicates
6. Augite
10. Beryl
20. Epidote
Carbonates, Borates
32. Hornblende
5. Aragonite
33. Kaolinite
7. Azurite
38. Olivine
13. Calcite
39. Opal
19. Dolomite
49. Rhodonite
36. Malachite
51. Sodalite
59. Ulexite
53. Staurolite
55. Talc
Phosphates, Sulfates
56. Topaz
4. Apatite
57. Tourmaline
9. Barite
58. Tremolite
14. Celestite
Garnet group
2. Almandine
31. Hematite
35. Magnetite
Gypsum varieties:
27. Alabaster
28. Satin Spar
29. Selenite
Mica Group
11. Biotite
34. Lepidolite
37. Muscovite
Quartz varieties
41. Agate/Onyx
42. Amethyst
43. Chalcedony
44. Citrine
45. Crystal
46. Jasper
47. Milky Quartz
Feldspar - Plagioclase
48. Rose Quartz
Series
1. Albite
Feldspar – potassium
feldspar
3. Microcline
[Amazonite]
21. Orthoclase
Specimen numbers are the
same as in previous and
current Science Olympiad
Rock and Mineral Kits that
may be ordered from Wards
Science Olympiad Kits.
*
Additional Minerals (Nationals only)
 Actinolite
 Kyanite
 Labradorite
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[plagioclase feldspar series]
Pyrolusite
Rhodochrosite
Rutile
Spodumene
Stilbite
Turquoise
Zircon
Labradorite feldspar
Kyanite
Zircon
Rhodochrosite
Rocks
Sedimentary (cont)
Metamorphic
60. Gneiss
61. Marble
62. Phyllite
63. Quartzite
64. Schist [Garnet]
65. Schist [Mica]
66. Slate
Igneous
67. Andesite
68. Basalt
69. Diorite
70. Gabbro
71. Granite
72. Obsidian
73. Pegmatite
74. Pumice
75. Rhyolite
76. Scoria
Sedimentary
78. Arkose
80. Breccia
81. Chert
Coal Varieties:
77. Anthracite
79. Bituminous
86. Lignite
82. Conglomerate
84. Diatomite
85. Dolomite Rock or Dolostone
86. Lignite Coal
Limestone varieties:
87. Chalk
83. Coquina
89. Fossiliferous limestone
90. Oolitic limestone
91. Travertine
92. Sandstone
93. Shale
Coaching Tips:
 Choose team members from different grade
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levels to avoid having to train a completely
new team the following year.
Experience is a true advantage for those teams
that remain on or near the top for many years
running!
Have your team practice with many real
samples
Compile a notebook that is easy to find
information
Visit local museums, mineral shows, etc.
Coaching Tips: Notebooks
 Participant notebooks are an integral part of the R & M
Event.
 The goal for permitting resources is to encourage
conceptual development in lieu of memorization of facts.
 Notebooks provide a framework for learning,
understanding, and quick reference.
 Participant-developed binders are generally more helpful
during the event than field guides.
 Field guides are not permitted during the competition this
year
Coaching Tips: Notebooks
 Survey: Any size binder OR 1-inch binder (recommended
by Earth Science Committee)
 Participants who construct their own note-books are
generally better prepared.
 Due to time constraints, a well-organized notebook
provides a much more efficient resource than most others.
Coaching Tips: Notebooks
 Notebooks provide an opportunity to organize facts in a
personalized format.
 Notebooks provide an opportunity to include information
from many sources.
 Notebooks provide a quick and easy means of checking
participant progress.
 WARNING! Events that permit resources are generally
much more challenging than those that do not. This is
done purposely!
Suggested Notebook Contents
 Devote one page to each Rock or Mineral specimen.
Alphabetize mineral section by mineral name; rocks by
type, then alphabetical. Each page should include, but is
not limited to:
a. One or more colored images
b. Mineral Group or Rock classification
c. Environment(s) of formation
d. Properties of the specimen
e. Formula or composition
f.
Commercial use
(Avoid too much info that results from printing web pages;
info should be easy to find & understand)
Suggested Notebook Contents
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(Alphabetized) glossary of important terms
Mohs scale of hardness
Mineral flow chart or ID Chart with Properties
Rock charts: igneous, sedimentary, and metamorphic
Bowen’s Reaction Series chart
Rock cycle diagram
Diagrams of common mineral crystal forms & habits
State Minerals
Resources
 Rock & Mineral kits
 Wards Science Rock and Mineral Kit
 Science Olympiad Rock & Mineral Kit (OLY01)
 ESES, P.O. Box 503, Lee’s Summit, MO 64063
 $85/kit including shipping (purchase orders or check)
Other Worlds Educational Enterprises –
Rock and Mineral CD, Exam packets, Rock and Mineral Kits
http://www.otherworlds-edu.com/RocksAndMinerals.htm
 Rock & Mineral Guides
 (Audubon, Simon & Schuster, Petersen, Golden)
 Science Olympiad Store
 http://store.soinc.org/default.aspx
• Science Olympiad Student Center
• Wiki - http://scioly.org/wiki/Rocks_and_Minerals
• Practice exams
• Scioly.org Test Exchange:
http://scioly.org/wiki/Test_Exchange
• Test Exchange Archive –
http://scioly.org/wiki/index.php/2014_Test_Exchange
• North Carolina Science Olympiad
http://www.sciencenc.com/event-help/rocksandminerals.php
• National Science Olympiad – event info
• https://www.soinc.org/rocks_minerals_c
Websites
Mineral & Gemstone Kingdom - general info on thousands of minerals and gems
http://www.minerals.net/
Mineral & Locality Database http://www.mindat.org/
USGS Educational Resources for Secondary Grades (7–12) – click on Rocks and Minerals
to get dozens of links http://education.usgs.gov/secondary.html#rocks
Rocks for Kids – info on mineral properties & characteristics
http://www.rocksforkids.com/RFK/identification.html
Geoman’s Mineral & Rock Charts
http://jersey.uoregon.edu/~mstrick/MinRockID/MinRockIndex.html
3 Basic Types of Rocks (Ask GeoMan)
http://jersey.uoregon.edu/~mstrick/AskGeoMan/geoQuerry13.html
James St John, Ohio State University Homepage – go to his links for Common Rocks,
Common Minerals, and Sediments for good descriptions & images
http://www.newark.osu.edu/facultystaff/personal/jstjohn/Documents/Home-page.htmmes
Sample Event Questions
STATION 1
1. Identify Mineral A.
A. Emerald
B. Beryl
2. Identify Mineral B.
A. Hornblende
B. Augite
C. Tourmaline
D. Olivine
C. Apatite
D. Tourmaline
E. Apatite
E. Topaz
Sample A
(Beryl)
3. Observe the properties of the minerals. Which statement best
describes the differences between them?
A.Sample A has about the same density as Sample B.
B.Sample A is harder than Sample B.
C. Sample A has a sub-metallic luster while Sample B is vitreous.
D. Sample A is hexagonal while Sample B is a prismatic crystal.
4. What is a use for Mineral B?
A.Fine quality crystals are cut into faceted semi-precious gems.
B.It is used as an abrasive because of its extreme hardness.
C. It is a common rock-forming mineral found in many igneous and
metamorphic rocks.
D. It is a source of beryllium.
Sample B
(Tourmaline)
STATION 2
5. What is the texture of igneous Rock A?
A.fine-grained
C coarse-grained
B. glassy
D. vesicular
6. What is the name of Rock B?
A.Gabbro C. Diorite
B.Granite D. Andesite
Sample A (Obsidian)
7. What is the name of Rock C ?
A.Gabbro C. Diorite
B.Granite D. Andesite
Sample B (Granite)
8. Which rock cooled at the fastest rate?
A
B
C
9. Which minerals are characteristic of Rock C?
A. Orthoclase feldspar & quartz
B. Plagioclase Feldspar & Olivine
C. Quartz & Olivine
D. Plagioclase Feldspar & Hornblende
Sample C (Diorite
Mineral Definition
More than 4,000 naturally occurring
minerals—inorganic solids that have a
characteristic chemical composition
and specific crystal structure—have
been found on Earth.
A substance needs to meet the
following criteria to be considered a
mineral:
 Naturally occurring
 Inorganic
 Solid
 Definite chemical composition
 Orderly internal crystal structure
Physical Properties of Minerals
 Each mineral has
different physical
and chemical
properties which
allow it to be
identified.
 Many of the more
common properties
are addressed in the
following slides.
Mineral Properties
Color
Color varieties of corundum
(sapphire)
Some Minerals Have a Distinct Color
Azurite
Copper
Pyrite
Gold
Sulfur
Malachite
Color
- tourmaline
Color may be
helpful but other
properties are
needed because:
The same mineral
has many color
varieties
Color
Halite
Selenite Gypsum
Different
minerals
have the
same color
or are
colorless!
Calcite
Quartz
Luster
the way a mineral reflects light
 Two General Types: Metallic & Nonmetallic

Metallic – shines like a metal
Can be dull metallic as
in magnetite
Luster
 Nonmetallic – doesn’t shine like a metal; many types including
adamantine, vitreous (glassy), dull/earthy, silky, waxy, resinous, pearly,
& greasy
Adamantine
Vitreous (glassy)
Silky
Earthy (dull)
Waxy
Resinous
Cleavage vs Fracture
-the way a mineral breaks when stressed
Cleavage – breakage in flat
surfaces along planes of weakness
Several basic forms based on #
directions
 One direction (basal)
 Two directional
 Three directional (not at right
angles; rhombic)
 Three directional (right
angles or cubic)
 Octohedral (4 – directions)
Cleavage examples:
Basal (Muscovite)
Cubic (Galena)
Two Directions (Feldspar)
Rhombohedral
(Calcite)
Octohedral (Fluorite)
Types of Fracture
-breaks in random directions (no planes of weakness)
Conchoidal (shell
like) - Quartz
Hackly (jagged edges) - Copper
Fibrous (narrow splinters) - asbestos
Uneven - Kaolinite
Hardness – minerals ability to resist scratching
Moh’s Scale of
Hardness
Relative scale
1 is softest; 10 is
hardest
Harder minerals
will scratch softer
ones
http://www.mineralogicalassociation.ca/young/images_page/Hardness.jpg
Streak
- powdered color of a mineral; non-metallic minerals usually have white or
no streak; metallic minerals have colored streak
Streak Color for a Few Common Minerals
Black - Graphite
Black - Pryite
Black - Magnetite
Black - Chalcopyrite
Gray - Galena
Limonite - Yellow-brown
Hematite - Red-brown
Specific Gravity or Density
S.G. - Ratio of density of mineral
compared to density of water
Can be determined by weighing
mineral suspended in water
Can also be calculated by
determining the mass and volume
of a mineral (density)
Light - Minerals with S.G. less
than 2
Medium – S.G. 2-4.5
Heavy – S.G. Greater than 4.5
Most silicates are 2.5-3.0
Most metallic minerals are heavy
Gold has a S.G. of 19.3!
Crystal Form (system) – the geometric shape that
crystals form in ideal conditions; there are 6 generally accepted
forms based on symmetry, but these are very difficult to
determine without advanced study. In NYS, we will only require
two of these: cubic (isometric) and hexagonal.
Cubic - pyrite
Hexagonal quartz
Crystal Systems
All minerals can be divided into
one of six crystal systems
based on symmetry. These
systems use three or four
imaginary lines, called axes, to
define the system based on the
length of the axis and the angle
that the axes intersect.
Understanding crystal systems
is very complex, and often can
not be determined by simple
observation of a crystal.
Students should be able to
indicate the crystal system for
each mineral based on their
research and their notes.
Identifying crystal systems will NOT
be required in New York
competitions except for isometric
(cubic) and hexagonal.
Mineral Habit – visible external shape of a mineral
Examples include acicular, bladed, prismatic, hexagonal, cubic,
rosette, botryoidal, striated, massive, radiating, twinning, &
granular.
 Twinning - staurolite
Acicular (needlelike) - actinolite
See Crystal Habit in Wikipedia for examples
http://en.wikipedia.org/wiki/Crystal_habit
Mineral Habits
 Botryoidal - hematite
 Bladed - kyanite
 Prismatic
Massive
 Rosette – barite rose
Transparency (diaphaneity)
Transparent
Translucent
Opaque
Special Properties
Magnetism magnetite
Double Refraction (birefringence)
- calcite
Fluorescence
Mineral
Properties are
determined by
the arrangement
of the atoms
Chart at right shows the
atomic arrangement of
several silicate minerals
and how it influences
breakage patterns
(cleavage or fracture)
Mineral Classification
– minerals are grouped into families based on chemical composition
 Native elements – minerals made
of a single element. Ex. copper, gold,
graphite, sulfur, silver
 Oxides – combination of a metal &
oxygen, common ore minerals. Ex.
Hematite (Fe), corundum (Al)
 Silicates - made from metals
combined with silicon and oxygen;
largest group of minerals; silicon
tetrahedron structure, most
common mineral family, many
subgroups; some are very complex.
Ex. Quartz, feldspars, micas, olivine,
hornblende, tourmaline, garnets,
augite, talc, epidote, etc.
 Sulfides: compounds of a metal
with sulfur, common ore minerals.
Ex. Galena (Pb), Sphalerite (Zn),
Pyrite (Fe), Chalcopyrite & Bornite
(Cu, Fe)
Mineral Classification – cont.
 Sulfates : compounds of sulfur with
metals and oxygen; contain SO4 ;
often form in evaporite
environments. Ex. Gypsum
(calcium), barite (barium), celestite
(strontium)
 Carbonates – minerals made of
carbon, oxygen, and a metallic
element (contain CO3); most fiz in
acid. Ex. Calcite, dolomite,
malachite.
Phosphates: contain PO4 ; not
as common. Ex. Apatite
Halides – form from halogen
elements (chlorine, fluorine) with
metallic elements. Usually very
soft and easily dissolved in water.
Ex. Halite (NaCl) and fluorite.
Formation of Minerals
Minerals form in a variety of ways in different
environments.
Crystallization from melt (igneous rocks)
Precipitation from water
 Evaporation of sea water forming chemical sedimentary rock such as
gypsum rock salt
 Hydrothermal ore deposits (ex. gold veins)
Chemical alteration during weathering or metamorphism
Precipitation from a vapor – ex. Sulfur in a volcanic region
Minerals as Resources (uses)
 Know how minerals are used and how they are non-renewable resources
 Ores - a mineral that contains enough of an element to make it economically
feasible to extract and process.
 Ex. Pyrite (sulfur), Galena (lead), Hematite (iron), Bauxite (aluminum),
Sphalerite (zinc)
 Minerals are used in every day life for everything from food supplements,
manufacturing, jewelry, building materials, electronics, ornamental objects,
etc. Students should know the uses of every mineral on list.
 Websites:
Northwest Mining Association
http://www.nwma.org/education/Uses%20for%20Minerals.htm
Geology .com
http://geology.com/minerals/
Gem Minerals
 Semi-precious vs
precious stones
 Mineral & their
gem varieties
ex. Beryl:
Aquamarine –
blue-green
Emerald – green
Morganite – pink
Corundum:
Sapphire –blue,
multiple colors
Ruby - red
Rocks
 A rock is an aggregate of one or more minerals.
 Rocks are the building blocks of the Earth's crust.
Rocks
 Igneous - crystallized from hot, molten rock
Examples: granite, basalt, pumice, obsidian
 Sedimentary - fragments of sediment laid down by
water or wind are compressed or cemented over
time
Examples: sandstone, shale, limestone
 Metamorphic - rocks changed by heat and or
pressure or chemical activity
Examples: gneiss, schist, slate, marble
Rock Cycle
http://rst.gsfc.nasa.gov/Sect2/rock_cycle_800x609.jpg
Igneous Rocks
 The term igneous means "fire-formed."
Igneous rocks crystallized from hot, molten magma or lava,
as it cooled.
 Magma is hot, molten rock beneath the surface of the
Earth.
 Lava is hot, molten rock that has flowed out and onto the
surface of the Earth.
 Igneous rocks make up more than 90% of Earth's crust, by
volume.
Igneous Rocks
Classified by Texture and Composition
 Texture of a rock is a description of its grain size. The rate
of cooling influences the texture of igneous rocks.
 Composition of a rock depends on the minerals it
contains
Extrusive rocks (volcanic) - cooled quickly at earth’s
surface): textures include fine grained (aphanitic), glassy,
vesicular (holes from gases)
Intrusive rocks (plutonic) cooled slowly beneath earth’s
surface from magmaslow cooling = coarse grained
Igneous Rocks
Igneous Rock Textures
 Glassy – cools very
fast; no crystals ex.
obsidian & pumice
 Fine grained
Obsidian showing glassy
texture
Pumice has glassy texture
but often doesn’t look like
glass due to holes from gases
(Aphanitic) – crystals
or grains smaller than 1
mm; cools relatively
fast from lava ex.
Basalt, rhyolite,
andesite
Basalt with illustrating uniform
appearance of fine grained texture
Basalt magnified 30 x under
microscope showing fine
crystals
Igneous Rock Textures

Coarse grained
(Phaneritic) – crystals
or grains larger than 1
mm; cools slowly from
magma, allowing
crystals to form. Ex.
Granite, Diorite,
Gabbro.
Granite showing coarse grained
texture with visible mineral crystals
Pegmatite is very coarse
grained, with minerals larger
than 10 mm. Pegmatites are
often the source of gem
minerals. Specimen at left
contains albite, muscovite,
and a garnet crystal.
Igneous Rock Textures
Vesicular – fine grained or glassy
rocks with holes from gases; rocks
solidify very quickly. Ex: scoria, vesicular
basalt, pumice
Porphyritic – a mix of some coarse
grained minerals in a fine matrix.
Porphyry deposits are formed when a
column of rising magma is cooled in two
stages. In the first stage, the magma is
cooled slowly deep in the crust, creating
the large crystal grains. In the final stage,
the magma is cooled rapidly at relatively
shallow depth or as it erupts from a
volcano, creating small grains that are
usually invisible to the unaided eye.
Igneous Environments of Formation
Environment of Formation:
Extrusive (Volcanic)
 Extrusive or volcanic rocks form from lava, which cooled
quickly on the Earth's surface.
Extrusive Rocks &
Types of Volcanic Eruptions
Mafic Lava
 Effusive eruptions with lava flows and little gas
 Oceanic crust
 Hot Spots
 Create shield volcanoes
 Rocks formed include basalt, scoria, basalt glass
 Ex. Hawaii
Felsic/Andesitic Lava
 Explosive eruptions with lots of





gas, volcanic ash, and pumice
Pyroclastic flows
Continental crust
Ocean/Continent subduction
zones
Create strato-volcanoes
Rocks formed include pumice,
rhyolite, andesite, obsidian
 Ex. Mt. St Helens (above right)
 Mt. Pinatubo (bottom right)
Intrusive Igneous Rocks
 Intrusive or plutonic igneous rocks formed from
magma which cooled deep beneath the surface of
the Earth.
 Examples: gabbro, diorite, granite
Igneous Rocks
Igneous Rocks – Composition

Felsic (or sialic) - Rich in silicon, oxygen, and
aluminum. Tends to have light-colored minerals
such as quartz and potassium feldspar.
Examples: granite, rhyolite.

Intermediate - Intermediate in composition
between felsic and mafic. Mixture of light and
dark minerals. Examples: diorite, andesite.

Mafic - Iron and magnesium rich. Typically
dark-colored. Examples: gabbro, basalt.
Composition of Igneous Rocks
Bowen’s Reaction Series
Intrusive Formations
http://www.geogrify.net/GEO1/Lectures/Landforms/IgneousProcess.html
Batholith - Creates topographic highs in
mountainous regions. Landforms "massive" in
character - lacking linear ridges & valleys. Rocks
are coarse to very coarse grained; often granites
and other phaneritic felsic rocks.
Example: Idaho Batholith (16,000 mi2); Sierra
Nevada Mountains (Yosemite)
Text From:
http://earthonlinemedia.com/ipg/outlines/lecture_igneous_rocks.html
Exposed Batholith
at Yosemite
National Park,
Sierra Nevada
Mountains,
California
 Dike - Magma cools in fractures
that cut across host rock. Form
linear ridges when exposed .
 Laccolith - Magma cools between
layers and warps overlying host
rock into mushroom shape. Forms
domes
 Sill - Magma cools between layers
of host rock. Example: Palisades
Sill
Dikes cutting across existing rocks
Sill intruded parallel to rock layers
Eroded laccolith
Sedimentary Rocks
 Sedimentary rocks cover about 75% of the world's
land area.
 Sedimentary rocks form when loose sediment
(gravel, sand, silt, or clay) becomes compact-ed
and/or cemented to form rock.
 The process of converting sediment to sedimentary
rock is called lithification.
 Sediment is deposited in horizontal layers called
beds or strata.
Distinguishing Characteristics of Sedimentary
Rocks
Layers of
sediments
Fossils
Grains
cemented
together
Textures of Sedimentary Rocks
Clastic – compacted & cemented rock
fragments; sediment derived from continents.
examples:


Shale, sandstone, conglomerate, breccia
Chemical/Biochemical (Crystalline) – examples:


Gypsum, rock salt, dolostone, travertine limestone
Organic (Bioclastic): examples:


Limestone (oolitic, fossil); Coal (bituminous,
anthracite)
Sedimentary Rocks
New York State Earth Science Reference Tables
Mesa Community College Sedimentary Rock Classification:
http://www.mesacc.edu/sites/default/files/pages/section/academic-departments/physical-science/geology/images/sedimentaryrkid1.jpg
Clastic
 Inorganic
 Composed of clay minerals,





quartz, feldspar, other mineral &
rock fragments
Formed by compaction &
cementation of grains
Rock fragments
Continental Environments
include rivers, alluvial fans,
desert sand dunes, deltas,
beaches, lakes
Rock type depends on grain size
Fossils may be present,
particularly in shale and
sandstone
Breccia – angular
fragments; mixed pebble
size and smaller
Sandstone – sand
sized; mostly quartz
Conglomerate – rounded
fragments; mixed pebble
size and smaller
Shale – clay sized
particles
Organic Sedimentary Rocks
 Formed from remains of
plants or animals
 Often monominerallic
 If limestone, fizz in acid
 Many types of
limestones due to
various environments
 May or may not have
visible fossils
Coal
 Composed of carbon
 Coal forms by compression and
carbonization of plant material
 Bituminous Coal is most common
 Most coal formed 300 million year
ago in swamp environments
where vegetation was abundant
 Anthracite Coal is the most pure
form of coal (92-98% carbon) and
burns the most efficiently. It
formed during mountain building
episodes when bituminous coal
was under heat and pressure. It is
often considered a metamorphic
rock, but is still found in
sedimentary sequences of
sandstone and shale.
Bituminous Coal
Anthracite Coal
Types of Limestone
 Composed of
calcum carbonate
(calcite or
aragonite)
 Most formed in
marine
environment from
skeletal remains
(shells, algae,
forams)
 Size of grains &
types of fossils
indicates
environment
Coquina – composed of shell
fragments 2mm or larger; forms
in high energy, shallow marine
environment (beach)
Fossil Limestone – any limestone
containing fossils; may be fine grained
or coarse grained; usually shallow
marine
Oolitic Limestone – formed from small spherical grains (oolites) with
concentric layers; formed in very shallow marine, high energy
intertidal environment or sometimes on lakebed by wave action.
Right: enlarged view of modern oolites from the Bahamas
Travertine
 Limestone formed from
precipitation of calcite or aragonite
in springs or caverns
 Often appears as layers of crystals
 It is a chemical/crystalline form of
limestone
 Often used as building material
Hand sample of travertine showing crystalline layers
Travertine terraces at Mammoth Hot Springs,
Wyoming
Stalactites in a cave are composed of travertine
Chalk & Diatomite
 Chalk and Diatomite are organic
sedimentary rocks composed of the
shells of microscopic one celled
photosynthetic protists
 Both rocks are light colored and
powdery
 Chalk is a type of limestone,
formed from forams and coccoliths
 Chalk is composed of calcite and
will bubble with acid
 Diatomite is composed of the
remains of diatoms
Chalk is composed of coccoliths
(microscope view on right)
 Diatom skeletons are composed of
opal (silica); diatomite is less dense
than chalk and will not bubble with
acid
 Chalk formed in moderately deep
marine environments
 Diatomite formed in lake or marine
environments
Diatomite is composed of diatoms
(microscopic view on right)
Chemical Sedimentary Rocks
 Crystalline rocks composed of one
mineral
 Rock salt (Halite) and Gypsum
form by the evaporation of water
(usually seawater) and the
precipitation of dissolved minerals.
 Chemical sedimentary rocks that
form by the evaporation of water
are called evaporites.
Rock Salt (Halite)
Rock Gypsum (alabaster)
Geology students walking on evaporitic
deposit of salt in western US
Chemical Sedimentary Rocks : Chert & Dolostone
 Chert is a fine grained silica rich
microcrystalline sedimentary rock. It
is composed of quartz (SiO2). It often
occurs as nodules in limestone or chalk
where it is believed to be a replacement
mineral. It occurs in layers as a primary
deposit in some areas. The banded iron
formations of Precambrian age are
composed of alternating layers of red
chert (jasper) with hematite.
 Chert comes in many colors, and the
dark grey to black form is often called
flint.
Chert specimens showing
different color varieties. Top
right: flint nodule in chalk.
Left: Banded iron with red
chert (jasper) and iron oxide
 Dolostone is composed of the mineral
dolomite and is often described as a
“non-descript” rock; looks like
driveway gravel.
 Most dolostone formed when
magnesium replaced calcium in
limestone or lime mud before
lithification.
 Often has vugs with dolomite crystals
Dolostone – looks fine grained and non-descript.
Right: vug in dolostone with dolomite crystals.
Sedimentary Environments
Rock Type, Fossils, & Sedimentary Structures Help Indicate Environment
Metamorphic Rocks
 Metamorphic rocks form when preexisting rocks (igneous, sedimentary, or
metamorphic) are exposed to high
temperatures and pressures under the
Earth's surface.
 The word metamorphic means "changed
form.”
 Metamorphic rocks can form from
sedimentary, igneous, or metamorphic
rocks
 Metamorphism causes changes in the
texture and mineralogy of other rocks.
 Metamorphism results from:
1.
High temperatures,
2.
High pressures, and
3.
Chemical reactions
Metamorphic Rock Classification
Metamorphic Textures:
Foliated
• Mineral grains are aligned
perpendicular to pressure
• Ranges from low grade with
microscopic grains (slate) to
high grade with large banding
Nonfoliated
Marble
Quartzite
Composition: calcite
Composition: quartz
Origin: metamorphism of
limestone
Origin: metamorphism of
sandstone
Identification: acid test;
softer than glass
Identification: harder than
glass
Grade of Metamorphism
Slate
Phyllite
Garnet Mica Schist
Gneiss
Low Grade ------------------------Medium Grade --------------------High Grade
Grade of Metamorphism
Grade of metamorphism depends on depth
and pressure
Types of Metamorphism
Contact metamorphism
Alteration of rock by heat adjacent to
hot molten lava or magma.
Economically important as setting for
metallic ores – gold, silver, copper, lead,
zinc, etc.
Regional metamorphism
large scale; associated with mountain
building
Grade increases with increasing depth
and pressure
Rocks are foliated (minerals are
aligned perpendicular to pressure)
Metamorphism - occurs with mountain building due to
plate collisions
Regional metamorphism often results in deformation
Contact Metamorphism
Igneous Intrusions cause contact
metamorphism
Metamorphic Minerals
 Common Metamorphic Minerals
Some pre-existing minerals, unstable at the higher
temperature and pressure conditions, transform into new minerals. Others recrystallize and
grow larger. Metamorphic rocks tend to be dominated by minerals you already know: feldspar,
quartz, muscovite, biotite, amphibole, and calcite/dolomite.
However, a few minerals are found exclusively or mainly in metamorphic rocks:
 Garnet – most common in metamorphic rocks; some in igneous rocks. Almandine is found in
schist, gneiss, and pegmatites.
 Staurolite – indicates intermediate to high grade regional metamorphism
 Kyanite - formed from high pressure metamorphism of clay minerals; found in gneisses and
schists
 Tremolite – forms from metamorphism of sediments rich in dolomite and quartz
 Talc – forms from metamorphism of magnesian minerals such as serpentine, olivine, pyroxene,
amphibole in the presence of carbon dioxide and water.
 Wollastonite – forms from thermal metamorphism of impure limestone or dolostone