Minerals

A mineral is:

  • naturally occuring

  • solid crystal substance

  • inorganic

  • Specific chemical composition


Minerals are formed by geologic processes like:

  • liquid magma into solid material


“Building blocks” of rocks


Naturally occuring

  1. Formed by natural processes

  2. Must be discovered in nature

Ordered internal Structure

  1. Made with ordered atoms

  2. Solid at normal temperatures

Inorganic

  1. Organic material usually has C or H, inorganic has one or the other

  2. Could be made by animals and still be organic



Examples of Minerals

Pyrite, Kyanite, Ice


Cube Zirconia and glass atoms aren’t minerals


Elements, Minerals, and Rocks

Crust is made of various rock types

  • Rocks are made up of bonded material (minerals usually)

  • Minerals are made up of elements

  • Elements are made of atoms


Atoms

  • Consist of subatomic particles (protons, neutrons, electons)

  • Protons/neutrons in nucleus, electons orbit


Ionic Bonding

Transferring of electrons


Covalent Bonding

Sharing of electrons


The atoms and how they are arranged determine the mineral’s shape

Ex. Silicate Mineral Structures


How do Minerals Form?

Minerals From Magma

  • Liquid rock made up of atoms with many different elements

  • Magma cools, atoms bond together forming repeating networks of multiple elements (Crystallization)


From Precipitation Out of Water

  • Minerals “undissolve” out of water

  • When ions that form in water becomes too concentrated, atoms increase and bond together

  • Crystallization and form new minerals (think of rock candy growing

  • Since minerals are solid, they collect on the waters bottom


From Increased Pressure and Temperature

  • Pressure and temperature increases to a point where original bonds become unstable, then atoms rearrange to form stable new bonds


Mineral Groups

Silicates

  • Most abundant minerals in Earth’s crust (making up of most rocks)

  • Fall into 2 categories: without iron (Fe) & magnesium (Mg) or with both

Ferromagnesian silicates – Olivine Family

  • Dense, dark-colored ferromagnesian (mafic) silicate

  • Contain iron, magnesium, or both combined with other elements

  • Iron (Fe) and magnesium (Mg) can freely substitute for each other in the crystal structure.

  • Because of this substitution, olivine is a mineral family

Ferromagnesian silicates – Pyroxene

  • Typically black or dark green,

  • Have a complex chemical composition that includes iron, magnesium, and aluminum.

Ferromagnesian silicates – Amphiboles

  • Composed of iron, magnesium, aluminum, and other cations bonded with silica tetrahedra

  • The most common amphibole, hornblende, is usually black but can vary in color.

Nonferromagnesian silicates

  • Lack iron and magnesium; may contain aluminum, calcium, potassium and/or sodium

  • Often light colored (white, light gray, or pink)

  • The most common examples: Quartz and feldspar group

Quartz

  • Made of a three-dimensional framework of pure silica tetrahedra, with no other elements present in its ideal form.

Feldspar

  • The most abundant mineral group in the Earth's crust (~50%)

  • Like quartz, it has a three-dimensional framework structure.

  • Two main types: One containing potassium found in continental crust rocks (alkali feldspar or orthoclase feldspar.

  • The other with sodium and calcium common in oceanic crust rocks (plagioclase feldspar).

Carbonates

  • Contain both carbon and oxygen

  • Examples: Calcite, Dolomite

  • Abundant in Earth’s crust, common in limestone and Dolomite

  • Forms with ionic bonds and acids break them apart

  • Forma ions, water molecules, and CO2 gas

Oxides

  • Ores of many important metals

  • Compounds of oxygen anion and metallic cations

  • Examples: Hematite and Magnetite

Sulfides

Ores of many important materials

  • Chalcopyrite– Source of about half of our copper–One of the most important industrial metals

  • Compounds of sulfide anion and metallic cations

  • Pyrite–Fe2S

Sulfates

  • Compounds of sulfate anion and metallic cations

  • Gypsum– Ca sulfate + water

Precipitation out of water


Native Metals

  • Metals

  • Occur in nature


How do I Know What Mineral It Is?

Minerals: Diagnostic Properties

To identify minerals we rely on physical, observable properties:

  • Color

  • Hardness – Indication of chemical bond strength

  • Cleavage - Planes of weakness

  • Fracture – no preferred planes of weakness

  • Luster – ability to reflect light

  • Streak – color of powder

  • Crystal shape (habit)

  • Transparency

  • Density - Mass per volume (g/cm3), Atomic weights of atoms, Packing

  • Reaction to acid

  • Even taste!


How Do We ID Minerals?

  1. Color

  2. Luster (Light reflection)

  3. Streak (Color showing when rubbing a mineral on a surface)

  4. Hardness

  5. Cleavage (Breaking into flat surfaces along planes of weak bonding

  6. Fracture (no plane or weakness)


Specific Gravity and Density

  • Specific gravity - ratio of weight of material to equal amount of volume

  • SG = Density of substance/Density of water