Properties of Rocks

1
Properties of Rocks

• Igneous, Sedimentary, Metamorphic

2
Igneous Composition

• Igneous rocks are mainly composed of silicate
  material.
• Because magma is largely composed of only 8
  elements, the major components of igneous rocks
  are the following
• silicon, oxygen, aluminum, calcium, sodium,
  potassium, magnesium and iron

3
Igneous Composition

• The color of the rock indicates the mineral
  components if the rock.
• Light colored silicates contain, greater amounts
  of sodium, potassium and calcium.
• Dark colored silicates contain greater amounts of
  iron and magnesium.
• Light colored silicates are contain more silica
  than dark colored silicates.
• Feldspars fall into this category and make up at
  least 40 of all the igneous rocks.

4
Formation of Igneous Rocks

• Igneous rocks form from magma, but all magma is
  not the same.
• A single volcano may extrude lavas exhibiting
  quite different compositions.
• The process by which magma crystallizes to form
  igneous rock is known as Bowens reaction series.

5
(No Transcript)
6
Bowens Reaction Series

• Minerals formed in the same general temperature
  range are found within the same igneous rock.
• Example Granite
• Granite always contains potassium feldspar,
  muscovite and quartz because they all crystallize
  within the same general temperature range.

7
Magmatic Differentiation

• Crystal setting- the earlier formed minerals are
  denser than the liquid portion and sink towards
  the bottom of the cooling magma chamber.
• The remaining magma cools and migrate into
  fractures in the surrounding rock forming a much
  different chemical composition than the parent
  magma.

8
Assimilation and Magma Mixing

• As magma migrates upward through the crust, it
  may incorporate some of the surrounding host rock
  through a process called assimiation.
• Often times, one magma body will intrude another
  magma body through a process called magma mixing.
• The two magma bodies may have very different
  chemical compositions.

9
Sedimentary Composition

• Sedimentary rocks form from the weathering of
  igneous rocks by running water, wind, waves, or
  glacial ice.
• After the sediment is transported to the new
  location, it undergoes lithification to form
  sedimentary rock.
• As piles of sediment accumulate, the materials
  near the bottom are compacted by the weight of
  the overlaying layers, causing them to cement.

10
Sedimentary Composition

• About 75 of all rock outcrops are sedimentary
  rock.
• Sedimentary rocks are a thin discontinuous layer
  in the upper portion of the Earths crust.
• Fossils are found in sedimentary rocks.
• Natural resources (coal and oil) come from
  sedimentary rocks.

Utahs Capital Reef National Park contains layers
of sedimentary rock called strata.
11
Lithification of Sediment

• The most common method of lithification is
  compaction.
• The weight of layers of sediment press the grains
  closer together reducing pore space.
• Shale is usually formed using the this method.
• Cementation is another method of lithification.
• The cementing material are carried through a
  water solution which eventually fills the pore
  spaces in the rock.
• Calcite, silica and iron oxide are the most
  common cements.

12
Metamorphic Composition

• Metamorphic rocks are produced from preexisting
  igneous, sedimentary or other metamorphic rocks.
• Metamorphism takes place when preexisting rocks
  are subjected to a chemical or physical
  environment that is significantly different from
  which it was initially formed.

13
Types of Metamorphism

• Low-grade metamorphism- slight changes
• Sedimentary shale becomes the more compact
  metamorphic rock slate.
• High-grade metamorphism- substantial changes.
• Sedimentary bitminous coal becomes antracite.

Shale
Slate
Anthracite Coal
Bituminous Coal
14
Metamorphism Settings

• Thermal Metamorphism- The rock is intruded by
  magma, and intense heat causes the change.
• Regional Metamorphism- Rocks undergo great
  temperature and pressure changes during mountain
  building processes.

15
Resources from Rocks

• The annual per capita consumption of nonmetallic
  and metallic mineral resources for the United
  States is about 10,000kg.
• About 94 of the materials used are nonmetallic.
• The per capita use of oil, coal, and natural gas
  exceeds 11,000kg.