Minerals

Ch 3.1

Minerals

• 3,500 known varieties

• new discoveries each year

Importance of minerals

• Used in everyday life– buildings, homes, roads, and machines

• Fertilize crops

• Added to foods

• Used in medicines

What is a Mineral?

• Naturally occurring

• Inorganic substance

• Specific atomic structure

• Definite chemical composition

Are these minerals?

• Pearl

• coal

• brass

• steel

• synthetic sapphires

• concrete

Rock forming minerals

• 10 minerals are SO common, they are 90% of the mass of earth’s crust

• quartz

• orthoclase

• plagioclase

• muscovite

• biotite

• calcite

• dolomite

• halite

• gypsum

• ferromagnesian (olivines, amphiboles)

Two groups of minerals

• Silicates

• Nonsilicates

Silicates Nonsilicates

• Contain Si & O• 96% of earth’s crust• Quartz• Feldspars

– most common

– Na, Ca, K

• Ferromagnesian– rich in Fe, Mg

• 4% of earth’s crust• no silicon• 6 major groups:

– carbonates

– halides

– native elements

– oxides

– sulfates

– sulfides

Crystalline structure

• Minerals have crystalline structure

• Specific geometric arrangement of atoms or ions

• Usually found as masses of crystals so small that you can see with microscope

• Sometimes large crystals form

Silicate crystalline structure

• Silcon-oxygen tetrahedron

• Basic building block:– 4 oxygen atoms– 1 silicon atom– pyramid shape with silicon atom in center

Bonding• Single chain (pyroxenes)

– share 2 oxygen atoms

• Double chain (amphiboles)

• Sheets (micas)– each tetrahedron shares 3 oxygen atoms– 4th Oxygen bonds with K or Al– split easily between O-K bond or O-Al bond– http://www.geo.wvu.edu/~donovan/geol101/ani

mations/03.swf

Network silicates

• Each Tetrahedron bonds to four neighboring tetrahedra

• Quartz

• Bonds are tight

• Minerals are hard…because bonds are tight

Biotite

Olivine(Mg, Fe)2SiO4image from: Mineralogie Uni Breme

Specimen from Jackson Co. North Carolina

Plagioclase Na(AlSi3O8)specimen from Hohe Tauern, Austria

Zircon ZrSiO4specimen from Norway

Mineral groups

• The minerals in each group often display similar properties and are commonly found together due to their similar chemical composition.

Carbonate GroupCalcite

image from www.yuprocks.com

Halide Group Fluorite

image from www.yuprocks.com

Native elementssilver

image from www.yuprocks.com

Native group: Platinum (Pt)collected: Ural Mountains, Russia

Native group: Diamond (C)crystal found Pomona, South-West Africa

Oxide groupgarnet

image from www.yuprocks.com

Oxide group hematite

image from www.yuprocks.com

Sulfate groupgypsum

image from www.yuprocks.com

Sulfate group gypsumimage from www.yuprocks.com

Sulfide groupgalena

image from www.yuprocks.com

Sulfide grouppyrite (fool’s gold)

image from www.yuprocks.com

Homework

• Read pages 66 - 69

Output

• Sketch and label 10 items that you use on a daily basis that have minerals in them.

• Be sure to identify the mineral that is used.