Minerals and rocks
1 / 76

Minerals and Rocks - PowerPoint PPT Presentation

  • Uploaded on

Minerals and Rocks. Lecture Outline. What are minerals? Common rock-forming minerals Physical properties of minerals Basic rock types The rock cycle. Minerals. A mineral is a naturally occurring, solid crystalline substance, generally inorganic, with a specific chemical composition.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about ' Minerals and Rocks' - lucy-gregory

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Lecture outline
Lecture Outline

  • What are minerals?

  • Common rock-forming minerals

  • Physical properties of minerals

  • Basic rock types

  • The rock cycle


A mineral is a naturally occurring, solid

crystalline substance, generally inorganic,

with a specific chemical composition

  • Natural

  • Solid

  • Atoms arranged in orderly repeating 3D array: crystalline

  • Not part of the tissue of an organism

  • Composition fixed or varies within defined limits

    Minerals are the “building blocks” of rock

Minerals and rocks

Large individual crystals (rare)

Mass of small grains: each is a crystal, but grown up against each other

Atomic structure of minerals
Atomic Structure of Minerals

  • NaCl - sodium chloride


Chemical bonds ionic
Chemical Bonds: Ionic

  • Electrical attraction between ions of opposite charge

    • Bond strength increases with the electrical charges of the ions

    • Bond strength decreases as the distance between the ions increases

  • Most minerals are this kind of compound

Minerals and rocks

Ionic Bonding example:






Covalent bonds
Covalent Bonds:

  • Electron sharing

  • Generally stronger than ionic bonds (e.g., diamond)

Crystallization of minerals
Crystallization of Minerals

  • Need starting material with atoms that can come together in the proper proportions

    • Growth from a liquid or a gas

  • Time and space for crystallization

  • Appropriate temperature and pressure

  • Examples

    • Magma that has cooled below its melting point

    • Supersaturated solution --> precipitation

Crystallization of minerals1
Crystallization of Minerals

  • Crystals begin as an initial “seed” - a microscopic crystal

  • Atoms keep being added in a 3D array, repeating the basic arrangement

  • Crystal faces are based on the array structure

Cations and anions
Cations and Anions

  • Anions are typically large

  • Cations are relatively small

  • Crystal structure is determined largely by the arrangement of the anions

Minerals and rocks

Common cations and anions

Radii given in angstroms; 10-8 cm

Ions can be compound
Ions can be compound

  • So far, we’ve talked about individual atomic ions

  • Many common minerals are silicates


Complex ions act as a single ion in forming crystal structure

Cation substitution
Cation Substitution

  • Crystal structure determined by those large anions

  • Various cations can substitute for each other in many minerals

    • Same crystal structure

    • Different chemical composition


Minerals with the same composition, but different crystal structure.

Minerals and rocks

Common Rock-Forming Minerals

Minerals fall into a small number of related “families” based mainly on the anion in them


  • Quartz (SiO2), K-feldspar (KAlSi3O8), olivine ((Mg, Fe)2SiO4), kaolinite (Al2Si2O5(OH)4)

  • Most abundant minerals in the Earth's crust

  • Silicate ion (tetrahedron), SiO44-

Silicate structure
Silicate structure

  • Most of the most common rocks in the crust are silicates

  • Silicate tetrahedra can combine in several ways to form many common minerals

  • Typical cations:

    K+, Ca+, Na+, Mg2+, Al3+, Fe2+


  • Cations with carbonate ion (CO32-)

  • Calcite (CaCO3), dolomite (CaMg(CO3)2), siderite (FeCO3), smithsonite (ZnCO3)

  • Make up many common rocks including limestone andmarble

  • Very important for CCS!

Minerals and rocks

CaCO3 + 2H+ = Ca2+ + CO2 + H2O


  • Compounds of metallic cations and oxygen

  • Important for many metal ores needed to make things (e.g., iron, chromium, titanium)

  • Ores are economically useful (i.e., possible to mine) mineral deposits


  • Metallic cations with sulfide (S2-) ion

  • Important for ores of copper, zinc, nickel, lead, iron

  • Pyrite (FeS2), galena (PbS)


  • Minerals with sulfate ion (SO42-)

  • Gypsum (CaSO4.H2O), anhydrite (CaSO4)

Minerals and rocks


  • Cave of the Crystals

  • 1,000 feet depth in the silver and lead Naica Mine

  • 150 degrees, with 100 % humidity

  • 4-ft diameter columns 50 ft length

Identification of minerals
Identification of Minerals

  • Chemical composition (microprobes and wet chemical methods)

  • Crystal structure (X-ray diffraction)

  • Physical properties

Physical properties1
Physical properties

  • Hardness

  • Cleavage: tendency of minerals to break along flat planar surfaces into geometries that are determined by their crystal structure

Physical properties2
Physical properties

  • Hardness

  • Cleavage

  • Fracture: tendency to break along other surfaces (not cleavage planes)

Physical properties3
Physical properties

  • Hardness

  • Cleavage

  • Fracture

  • Luster (metallic, vitreous, resinous, earthy, etc.)

  • Color (often a poor indicator; streak color is better)

  • Specific gravity

  • Crystal habit (shape)


An aggregate of one or more minerals; or a body of undifferentiated mineral matter (e.g., obsidian); or of solid organic matter (e.g., coal)

  • More than one crystal

  • Volcanic glass

  • Solidified organic matter

  • Appearance controlled by composition and size and arrangement of aggregate grains (texture)

Rock types
Rock Types

  • Igneous

    • Form by solidification of molten rock (magma)

  • Sedimentary

    • Form by lithification of sediment (sand, silt, clay, shells)

  • Metamorphic

    • Form by transformations of preexisting rocks (in the solid state)

  • Igneous rocks
    Igneous Rocks



    Intrusive plutonic
    Intrusive (plutonic)

    • Form within the Earth

    • Slow cooling

    • Interlocking large crystals

    • Example = granite

    Extrusive volcanic
    Extrusive (volcanic)

    • Form on the surface of the Earth as a result of volcanic eruption

    • Rapid cooling

    • Glassy and/or fine-grained texture

    • Example = basalt

    Origin of sediment
    Origin of sediment

    • Produced by weathering and erosion or by precipitation from solution

    • Weathering = chemical and mechanical breakdown of rocks

    • Erosion = processes that get the weathered material moving

    Sediment types
    Sediment types

    • Clastic sediments are derived from the physical deposition of particles produced by weathering and erosion of preexisting rock.

    • Chemical and biochemical sediments are precipitated from solution.

    Minerals and rocks




    • The process that converts sediments into solid rock

    • Compaction

    • Cementation

    Minerals and rocks



    Minerals and rocks