Hardness Mohs Hardness Scale

1. Talc2. Gypsum

2.5 finger nail 3.5 penny

3. Calcite4. Fluorite5. Apatite

5.0 nail 5.0-6.0 glass and knife blade

6. Orthoclase (feldspar) 7. Quartz 8. Topaz 9. Corundun10. Diamond

Striations Striations

odormagneticDouble Refraction

Mineral Resources

Ore -- mineral that can be mined for a profit

Gangue --worthless minerals in

an ore body

examples of oresAg silverAu goldCopper sulfides (covellite)Fe oxides (hematite)PbS lead sulfide (galena)

The U.S.A imports about 80% of the most used 16 metals!

Fig. 3.1

IGNEOUS ROCKS

Magma- mostly silicate

500 – 1200 oCmobilenatural

Fig. 3.2

Extrusive - crystallized fromlava (aphanitic texture)

Intrusive – crystallized frommagma (phaneritic texture

Volcano- conical hill formed around an opening in the earth’s surface where hot rock (pyrocastic debris), gases and magma erupt.

Crater vs Caldera

Opening in volcano.

If 10,000 ft or greater in diameter, it is a caldera.

Less than10,000 ft diameter makes it a crater.

Fig. 4.3

Fig. 4.3a-d

Fig. 4.14

Gases:

steamcarbon dioxide (CO2)

sulfur oxide methane ammonia nitrogenhydrogenresulting in acids

Fumeroles- volcanoes where “only” gases are expelled.

Two explanations:

1.initial stage of volcanic formation

2. special class of volcanoe (only gases are expelled)

Pyroclastic Material –

Formed by the explosive action of the gases, e.g.,

pumice.

Pyroclasticsdust-ashcinderslapilli

blocks

bombs

Pumice

vesicles – “fossil” gas(bubbles in lava)

Box 4.5.1

Fig. 4.12

Fig. 4.6

Classification of VolcanoesshieldHawaii

cinder coneParicutin, Mexico

strata cone or compositelava

Vesuvius, Italy

0027

0028

0034

Box 4.6.1

Types of Lava Flows1. Pahoehoe – smooth, ropeytexture, i.e., “fluid”

2. Aa – rough texture, viscous, not as hot, not as much gas content

Fig. 4.16

Fig. 4.17

Fig. 4.19b

Fig. 4.22

Fig. 3.24

http://comp.uark.edu/~ksteele/

GENERAL GEOLOGY 1113; SEC 04 Instructor: Roc Doc

Last updated 01-20-2006

 

SYALLBUS          

 

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Fig. 4.22

Extrusive - crystallized from lava (aphanitic texture)

Intrusive – crystallized from magma (phaneritic texture

TYPES OF MAGMA

1. granite ------ rhyolite“coarse” “fine”

phaneritic aphanitic

silica (SiO2) richfeldspar and quartz

2. basalt---------gabbro “fine” “coarse” aphanitic phaneritic

iron – magnesium (Fe – Mg) richferromagnesian minerals,

plagioclase (Ca, Na feldspar)

Granite 30 miles

Basalt 5 miles

Basaltic = maficGranitic = felsic = silic

Fig. 4.30

Fig. 4.29

Fig. 4.28

Fig. 4.27