PreQuiz
1. Describe the strength of bonds between atoms
in a solid.
2. What is a mineral?
3. True or False: Only eight elements make up
the bulk of the minerals found in Earth’s crust.
4. What is the most common mineral group?
a. carbonates
b. silicates
c. oxides
d. halides
5. What are rock-forming minerals?
6. What are some common properties of
minerals?
3.1 The Rock Cycle
• rock- any solid mass of mineral or minerallike matter that occurs naturally as part of
our planet
– Mixtures of minerals and sometime
nonmineral material
• 3 major types of rocks:
– Igneous
– Sedimentary
– metamorphic
Rock Cycle
Summary Questions
• Use your own words to describe the sequence of
processes that result in igneous rocks. Describe
a specific example of a sedimentary rock
becoming an igneous rock.
• Use your own words to describe the sequence of
processes that result in sedimentary rocks.
Describe a specific example of a sedimentary
rock becoming a new type of sedimentary rock.
• Use your own words to describe the sequence of
processes that result in metamorphic rocks.
Describe a specific example of a sedimentary
rock becoming a metamorphic rock.
Igneous Rocks
• Formation
– Intrusive Igneous Rocks
• Rocks that form when magma hardens beneath
Earth’s surface
– Magma- molten material below earth’s surface
– Extrusive Igneous Rocks
• Rocks that form when lava hardens on Earth’s
surface
– Lava- molten material on or above earth’s surface
granite
rhyolite
Texture of Igneous Rocks
• Igneous Rocks are classified by texture and
composition
• Textures
– Coarse-grained- slow cooling results in large crystals
– Fine-grained-rapid cooling results in rocks with small,
interconnected mineral grains
– Glassy- cools so quickly that ions cannot arrange
themselves into a network of crystals
• Glassy does not mean they look glassy!!! (pumice)
– Porphyritic- rocks experience different rates of
cooling, so they have different sizes of crystals in the
same rock
Igneous Textures
Fine-grained
Coarse-grained
Glassy
Porphyritic
Examples of Igneous Rocks
1. Granite
2. Rhyolite
3. Gabbro
4. Basalt
5. Obsidian
6. Pumice
Sedimentary Rocks
• Formation (5 major processes)
– Weathering- breaks rocks into sediments
• Sediments- smaller pieces of rocks and minerals
– Erosion- movement of sediments
• Agents: water, wind, ice, or gravity
– Deposition- dropping of sediments because
agent lost energy
– Compaction- squeezing or compacting of
sediments
– Cementation- dissolved minerals are
deposited in the tiny spaces among the
sediments
Classification of S.R.
• Classified according to the way they form
– Clastic sedimentary rocks- made of
weathered bits of rocks and minerals
• Grouped according to the size of the sediments
– Conglomerate- rounded, gravel-size or larger
– Breccia- angular
– Chemical sedimentary rocks- forms when
dissolved minerals precipitate from water
solutions
Features of S.R.
• The many unique features of sedimentary
rocks are clues to how, when, and where
the rocks formed
– Layers show the order in which the rocks
formed
– Fossils hidden in sedimentary rocks show
evidence of past life forms
– Ripple marks and mud cracks
Examples of S.R.
•
•
•
•
•
Conglomerate
Breccia
Sandstone
Limestone
Rock salt
Metamorphic Rocks
• Metamorphism- to change form
• Formation
– Changes occur at elevated temperatures and
pressures
– Conditions are found a few kilometers below Earth’s
surface and extend into the upper mantle
• Agents
– Heat- provides energy needed to drive chemical
reactions, which may cause minerals to recrystallize
– Pressure- may cause the spaces between mineral
grains to close or cause the mineral to recrystallize
– Hydrothermal Solutions- hot water solutions
promote recrystallization by dissolving original
minerals and then depositing new ones
Classification of M.R.
• Classified by texture and composition
• Texture
– Foliated-rocks with layered or banded
appearances
• Formed when rocks undergo intense pressures
causing the rock to be more compact or even
recrystallize the rock
– Nonfoliated- rocks without banded
appearances
• Contain only one mineral
Contact vs. Regional
• Contact Metamorphism
– When magma intrudes rock
– Produces low-grade metamorphism = minor
changes
• Ex: Marble
• Regional Metamorphism
– During mountain building, rocks are exposed
to extreme pressures and temperatures
– Produces high-grade metamorphism =
intense changes
Examples of M.R.
•
Parent rock- original
rock before
metamorphism takes
place
Metamorphic
Rock
Parent Rock
Slate
Shale
Gneiss
Schist, Granite
Marble
Limestone
Quartzite
Sandstone
Schist
Phyllite
Anthracite
Bituminous Coal