BAESI: Minerals

November 19, 2011

Ellen Metzger

Bay Area Earth Science Institute Since 1990 Web Site: www.baesi.org

“One-stop shopping” A collection of podcasts, ready-to-use

classroom activities, and other resources for

teaching about plate tectonics, climate

change, and other topics

Acknowledgements The BAESI Saturday workshop program is made

possible by a grant from Chevron.  Geologic maps of California supplied by the

Northern California Geological Society and the American Association of Petroleum Geologists Foundation.

What is a mineral?

What is a Mineral?

A mineral is a naturally-occurring, inorganicsolid with a definite (but generally not fixed)chemical composition and an orderlyinternal arrangement of atoms (crystalline).

Examples of chemical formulas for minerals:

Quartz: SiO2

Pyrite: FeS2

Crystalline

Halite - NaCl Definite chemical composition Orderly arrangement of atoms

Both are crystalline

http://skywalker.cochise.edu/wellerr/VGM/mineral-hall.htm

Virtual Geology Museum at Cochise College – Copyright-free phtos

http://www.slideshare.net/johnthebillionaire/naica-crystal-cave-80324

"Walking into either of these caves is like stepping into a gigantic geode," said Richard D. Fisher, an American consultant with the mining company to develop the discoveries as tourist attractions. Fisher said that most people can endure only a few minutes in the caves due to their high temperatures.

Mineral Identification

What properties can be used to identify minerals?

What do you observe?

Physical properties used to identify minerals

Color Streak Luster Hardness Cleavage/fracture Specific gravity (“heft’) Reaction with dilute HCl (or vinegar) Magnetism Crystal habit or form

Color

All of these are quartz.

Two Forms of Hematite: Same Streak

http://www.li-edu.com/hematite.gif

http://www.belmont.sd62.bc.ca/teacher/geology12/photos/minerals/streak_hematite.jpg

Luster

Pyrite: Metallic Luster Halite: Nonmetallic Luster

Shiny does not equal metallic.

Moh’s Scale of Hardness1 = Talc 2 = Gypsum 3 = Calcite 4 = Fluorite 5 = Apatite6 = Orthoclase 7 = Quartz 8 = Topaz 9 = Corundum 10 = Diamond

Hardness of everyday objectsFingernail: 2.5Penny ~ 3.5Glass and a steel nail: 5.5 and

Examples of Cleavage

http://upload.wikimedia.org/wikipedia/commons/9/93/Mineral-cleavage.gif

Look for signs of breakage: “steps” on mineral surfaces

Fracture: Irregular Breakage

http://geophysics.ou.edu/geol1114/notes/minerals/conchoidal.jpg

Quartz has conchoidal (curving fracture)

California’s Unique Rocks and Minerals Blueschist Graywacke Serpentinite

California’s Non-fuel Mineral Production, 2007

California’s Mineral Resources What is our state gem? Our state mineral? Our state rock?