Rocks and Minerals Ch. 1 and 2

Grouping minerals How can you group the minerals your group has been given? Think of how you group other things in nature: Clouds Trees Birds Buildings

What is a mineral? A naturally occurring inorganic solid with a definite (but not fixed) chemical composition and a highly ordered arrangement

Minerals are made from elements Most common elements: Oxygen Silicon Aluminum Iron Calcium Magnesium Sodium Potassium Percentage by Weight

Properties of Minerals Crystal form Habit Cleavage Hardness Luster Color Streak Density Did you use any of these properties for grouping your minerals?

Crystal Form- Internal arrangement of atoms determines outward appearance

Habit-shape of a mineral or group of minerals

Geode Stalactitic Botryoidal Habit Mammillary Radiating Fibrous

Cleavage-preferred plane of weakness Do all minerals have cleavage?

Mohs Hardness Scale 3 4 5 1 2 9 10 6 7 8

Mohs Hardness Scale fingernail Copper penny glass Streak plate softest 1 - Talc 2 - Gypsum 3 - Calcite 4 - Fluorite 5 - Apatite 6 - Potassium Feldspar 7 - Quartz 8 - Topaz 9 - Corundum 10 -Diamond fingernail Copper penny glass Streak plate hardest

Luster-how a mineral reflects light Metallic - metal like Vitreous - glass like Resinous - resin like Pearly - pearl like Greasy - slippery Non Metallic

Luster Metallic Nonmetallic

Color-what is the usefulness of this attribute in identifying minerals?

Color of Streak

Density box of feathers box of hammers

Important crustal minerals Feldspar group (plagioclase and orthoclase) Quartz Calcite and dolomite Pyroxene group Amphibole group (biotite and muscovite) Olivine Halite (salt) gypsum

What is a rock? An aggregate of one or more minerals

Groups of rocks Igneous Sedimentary Metamorphic Characterized by how they form Related by the rock cycle

Rock Cycle

Igneous rocks Crystallize from a molten rock: magma Magma: liquid rock beneath earth’s surface Lava: liquid rock above earth’s surface Igneous rocks classified on Mineral size composition

Igneous rocks Intrusive igneous rocks Extrusive igneous rocks Cool below ground (slowly) All minerals visible w/out microscope Extrusive igneous rocks Cool above ground (fast) Most minerals too small to see w/out microscope

Igneous rocks Intrusive igneous rocks Extrusive igneous rocks

Intrusive or extrusive?

Slow or fast cooling?

Intrusive or extrusive?

Slow or fast cooling?

Light colored igneous rocks Granite and rhyolite

Intermediate igneous rocks Andesite

Dark colored igneous rocks Gabbro and basalt

Rock Cycle Igneous rocks can become what other kind of rocks?

Sedimentary rocks Clastic sed rock: made of solid particles once part of other rocks Classified by grain size Chemical sed rock: made from dissolved material in water Classified by chemical composition Biochemical sed rock: made of dead plants and animals

Biochemical, chemical, or detrital?

Clastic sed rocks Big particles Conglomerate Sand size Sandstone Small particles Mudstone (shale)

Clastic sed rocks Conglomerate Clue: Particles of lots of different sizes

Clastic sed rocks Sandstone Clue: feels sandy

Clastic sed rocks Mudstone (shale) Clue: very small particles No grit when you taste it

Chemical sed rocks Limestone Made of calcite Clues: fizzes with acid Often contains fossils

Chemical sed rocks Rock salt/halite Gypsum Clue: tastes salty Clue: easily scratched, not salty

Biochemical sed rocks Category of chemical sed rocks Coal Limestone if with fossils

Importance of sed rocks Key to interpreting Earth’s history