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Earth and Space Science
Semester 2 Review
Part 2
Cleavage
- Minerals that split easily or break apart in one direction along a flat surface.
Core sample
- A cylindrical shape cut out of a rock or earthen surface that geologists can examine and study.
Crystal shape
-In minerals, a repeated crystal pattern is evident throughout with similar faces, edges and
corners.
-The pattern is one of the criteria or properties that give a particular mineral its identity.
Deposition
-The process that follows weathering and erosion in the formation of a Sedimentary Rock.
-Minerals and sediments are deposited in layers, often in the bottom of a body of water,
followed by their compaction and cementation.
Elements
-Natural and man-made substances with unique atomic structures that can be organized on the
Periodic Table.
-All minerals have a definite chemical composition.
-They either contain a pure element like silver or gold or have compounds of elements in
proportionate amounts like the silicates.
-The silicates are the most common minerals found on or in the crust.
-Silicate minerals are made of crystals formed by silicon and oxygen compounds.
Compounds
- A substance formed by one or more elements that are chemically combined.
-Most minerals are compounds of one or more elements.
Erosion
-The breakdown (Weathering (physical and chemical)) and transportation of sediments,
minerals and rocks by water, wind or ice.
Foliation
-When crystal grains of a Metamorphic Rock are arranged in parallel layers.
-Metamorphic Rocks with randomly arranged crystals are said to be non-foliated.
Hardness
- Used to identify a mineral’s identity.
-Geologist Moh developed a hardness scale starting with (1) Talc (softest) and ending with (10)
Diamond (hardest).
-Moh’s Hardness scale allowed Geologists to see that any mineral can scratch any other mineral
that is softer than itself.
Igneous
-One of three rock types.
-The name comes from the Latin word “ignis” which means fire.
- Igneous Rocks that form from magma beneath the Earth’s surface are called “intrusive”
igneous rocks.
-Igneous rocks that form from lava above the Earth’s surface are called “extrusive” igneous
rocks.
Landform
-Any feature on the Earth’s surface caused by erosion, sedimentation or plate movement.
- Some examples include hills, valleys, deltas, mountains or plateaus.
Lithification
-The process of forming a rock from sediments usually by compaction and cementation.
Metamorphic Rock
- A type of rock formed deep inside the Earth that changes an existing rock with tremendous
amounts of heat and pressure over millions of years.
Minerals
- Make up rocks.
-They are:
1. Naturally occurring.
2. Inorganic.
3. Solid.
4. Crystal structure.
5. Definite chemical composition.
Minerals
-Are identified by their:
1. Color.
2. Streak (Identify the color of a mineral on a Streak Plate).
3. Luster (How the mineral reflects light).
4. Density (volume displacement in water; Mass (g)/Volume (ml)).
5. Moh’s Hardness Scale.
6. Crystal structure (cubic, hexagonal, tetragonal and others).
7. Cleavage and fracture.
8. Special properties (glowing, magnetism).
Oxygen
- An abundant element that is found in the atmosphere, water and rocks.
Rock Cycle
-An endless cycle of rock formation and sedimentation that can veer toward many pathways.
-Pathways depend on the physical processes involved
cementation/heat and pressure/melting/cooling and hardening).
(deposition,
compaction,
Sedimentary Rock
-One of three rock types.
- They are found on or in the crust.
-They can be classified as either Clastic (particles and fragments are squeezed together) or
Organic (formed by remains of plants and animals) or Chemical (formed by mineral deposits left
when seas or lakes evaporate.
Silicon
-An element that can chemically combine with oxygen to form a silicate; a common mineral.
Streak
-The color of a mineral in a powder form. The color does not always appear as the actual color
of the mineral.
Weathering
-The physical (mechanical) and chemical breakdown of a mineral or rock into smaller pieces.
-Processes include freezing and thawing, hot and cold temperatures, ice, wind, water and acidic
and salty solutions.
- Plant roots are also factors that can affect weathering.
Identify physical properties of rocks.
-Geologists observe and study the rock’s mineral composition, color and texture (grain size).
-Some rocks have large size grains and are defined as “course-grained.”
- Igneous rocks form from the cooling of molten rock (magma or lava).
-Sedimentary rocks form from the particles of other rocks, the remains of plants and animals
and the formation of crystals from dissolved mineral solutions.
-Metamorphic rocks form from existing rocks when extreme heat and pressure are applied over
millions of years.
Describe the Rock Cycle.
-The Rock Cycle is a series of natural processes by which rocks slowly change from one kind of
rock to another.
-The processes include melting; weathering and erosion, deposition, compaction, cementation;
cooling and hardening; heat and pressure.
-The Rock Cycle can change any of the three rock types into another rock type or another rock
within the same rock type family (S., I. M.).
-Rocks change over time as well as the paths they take in the Rock Cycle.
Explain how erosion affects the Rock Cycle.
-Weathering and erosion breaks down rock particles of Sedimentary, Igneous and Metamorphic
rocks that are found mostly on or in the crust.
Identify silicon and oxygen as elements commonly found in minerals.
-The most common mineral found on or in the crust is the family of Silicate minerals which are
formed from the chemical bonding of the elements silicon and oxygen.
- Glass is made from silicates.
- The sand on the beach is classified as silicate minerals.
Describe how Igneous rocks with a large grain size form on Earth.
-Slow cooling magma form course grain (large) crystals inside the earth and are classified as
Intrusive Igneous rocks.
Given a table, compare the hardness of different minerals.
Moh’s Hardness Scale is 1-10, 1 (Talc) being the softest and 10 (Diamond) the hardest minerals.
-Each mineral can scratch a mineral with a lesser number.
-For example, a “2” can scratch a 1 but not a “3.”
Given a table, compare the density of different minerals.
-A Petrologist will measure the mass (g) of the mineral and then perform a volume
displacement procedure in water to determine how many ml the water rose.
- Mass (g)/Volume (ml) = Density of the mineral.
Compare the origin and chemical composition of I. M. and S. rocks.
Igneous
Metamorphic
Sedimentary
Extrusive-Formed by lava on the
Crust.
Formed by Heat and Pressure
beneath the Earth’s surface.
-Lava low in silica usually forms
dark colored rocks.
-Appearance, texture, crystal
structure and mineral content
change.
Clastic-rock fragments are
squeezed together.
-Can form out of all three rock
types.
-large and small particles.
-Extrusive Igneous rocks have a
fine-grained or glassy texture.
-Rapid cooling lava forms fine –
grain rocks with small crystals
(Exception is Volcanic glass like
Obsidian which has no crystal
structure.)
-Formed from Sediments found
on or in the crust.
-Classified by the arrangement of Examplesthe grains that make up the rock.
Foliated Crystals- grains
arranged in parallel layers.
Examples-
Organic – plant and animal
remains deposited in thick
layers.
ExamplesExamplesIntrusive-formed by magma in
the Crust.
-Magma high in Silica usually
forms light- colored rocks.
Nonfoliated Crystals- grains are
randomly arranged.
Chemical- occurs when minerals
in a solution dissolve and
crystallize because of
evaporation.
Examples-Intrusive rocks have larger
crystals than Extrusive Igneous
rocks.
Examples-
-Slow –cooling magma forms
course-grained rock with large
crystals.
Identify the processes responsible for the formation of sedimentary rocks.
-Weathering (physical, mechanical and chemical) and erosion; deposition; compaction; cementation.