Minerals of the Earth

Minerals of the Earth : 

Minerals of the Earth Chapter 9

9.1 What is a Mineral : 

9.1 What is a Mineral A mineral is a natural, inorganic, crystalline solid. 20 rock forming minerals

Slide 3: 

10 are common: Quartz, orthoclase, plagioclase, muscovite, biotite, calcite, dolomite, halite, gypsum, ferromagnesian minerals (olivines, pyroxenes, and amphiboles).

Quartz : 

Quartz

Orthoclase : 

Orthoclase Feldspar

Plagioclase : 

Plagioclase Feldspar Tough to identify

Muscovite : 

Muscovite

Biotite : 

Biotite

Calcite : 

Calcite Double refraction

Dolomite : 

Dolomite

Halite : 

Halite

Gypsum : 

Gypsum

Ferromagnesian Minerals : 

Ferromagnesian Minerals Olivine peridot

Amphiboles : 

Amphiboles Hornblende

Pyroxenes : 

Pyroxenes Green mineral

Silicate Minerals : 

Silicate Minerals Si and O Quartz is only Si and O Feldspar depends on type of metal Orthoclase formed with K Plagioclase is formed with Na and or Ca

Slide 17: 

Silicate minerals, Cont. Ferromagnesian Fe and Mg hornblende, olivine, muscovite, biotite

Non silicate minerals : 

Non silicate minerals 4% of crust Carbonates- Contain CO3 CaCO3, (Calcite) Halides- Contain Cl, F with Na K, Ca, CaF2 (Fluorite) NaCl (Halite)

Slide 19: 

Non silicate minerals, continued Native Elements, (Copper, Silver, gold) Oxides- O with something besides Si, Al2O3 (Corundum)

Non silicate, Cont. : 

Non silicate, Cont. Sulfates- Contain SO4, CaSO4 (Gypsum) Sulfides- Elements with Sulfur, PbS (Galena)

Crystalline Structure : 

Crystalline Structure Crystal is a natural solid with a definite shape this shape reflects the atomic structure Crystals are usually microscopic Si-O Tetrahedra

Si O Tetrahedron : 

Si O Tetrahedron http://www.geo.wvu.edu/~donovan/geol101/animations/03.swf

Slide 24: 

single chain (pyroxenes), double chains (amphiboles), sheets (micas) The tetrahedra can form 3 shapes

Slide 25: 

http://www.geojeff.org/course-materials/physical-geology-lab/lab-2-minerals-i/silicate-structure Pyroxenes, (Augite)

Slide 26: 

Amphiboles, (Hornblende)

Slide 27: 

Sheet, Micas

Slide 28: 

Network silicates, Quartz O and Feldspar Al Each tetrahedron is bonded to four others

9.2 Identifying Minerals : 

9.2 Identifying Minerals Minerals have specific characteristics that allow us to identify them Color, Luster, Streak, Cleavage and Fracture, Hardness, Crystal Shape, Density

Color : 

Color Color is the simplest character to identify, however it can be unreliable due to small changes in chemical composition, different minerals being similar in color, and weathering changing the color.

Luster : 

Luster Luster is a description of how light reflects off a mineral Metallic, waxy, earthy, dull

Streak : 

Streak Mineral in powdered form Rub sample against tile plate

Cleavage and Fracture : 

Cleavage and Fracture Cleavage is the tendency to split along certain flat surfaces Some minerals fracture, they break along irregular surfaces

Hardness : 

Hardness The ability to resist scratching Moh’s Hardness Scale, 1 being softest (Talc) and 10 being hardest (diamond)

Crystal Shape : 

Crystal Shape 6 Shapes: Isometric,Triclinic, Hexagonal, Orthorhombic, monoclinic, Tetragonal

Density : 

Density Also heft or specific gravity

Special Properties : 

Special Properties Magnetism Fluorescence and Phosphorescence Double Refraction Radioactivity

Fluorescence : 

Fluorescence

Phosphorescence : 

Phosphorescence

Credits : 

Credits Images from http://www.em.gov.bc.ca/Mining/Geolsurv/Publications/InfoCirc/IC1987-05/rockmin.htm http://www.geojeff.org/course-materials/physical-geology-lab/lab-2-minerals-i/silicate-structure Mineral Images from (c) 2005 Andrew Alden, licensed to About.com, Inc. http://geology.about.com/library/bl/images/blmineralindex.htm