Sedimentary

Igneous

Metamorphic

What are minerals?

• Minerals are naturally occurring, nonliving substances found in Earth.

• They have a chemical formula, and a definite internal structure.

Characteristics of Minerals

• There are 3500 known minerals in Earth’s crust.

• No more than 20 of these are commonly found in rocks.

• Rocks are therefore made up of combinations of minerals cemented together under extreme heat and pressure.

Rock forming minerals

• Feldspar• Pyroxene• Mica• Olivine• Dolomite• Quartz• Amphibole• Clay• Calcite

Rock characteristics

• Porous, granular, or smooth

• Soft or hard

• Densities

The appearance reflects it’s mineral composition and how it was formed!

Identifying Minerals by physical characteristics

1. Color

2. Luster

3. Transparency

4. Cleavage

5. Fracture

6. Streak

7. Hardness

Igneous Rocks

• Igneous – from fire

• Magma – molten material inside the earth.

• Lava – molten material which flows on or above the earth’s surface.

Igneous Rocks

• Igneous rock forms when molten rock cools and solidifies.

• Intrusive: cools within the earth.

• Extrusive: cools on or above the earth’s surface.

• Made of various mineral crystals.

• The more quickly the rock cools, the less the crystals grow.

Examples of Igneous Rocks

Granite Basalt

Course Grained

Cooling is slow; thousands to millions of years

Cools below the ground - intrusive

Minerals can be seen with the naked eye

Fine Grained

This rock has cooled “quickly” days to weeksMinerals do not have time to growGrains are very small – above ground - extrusiveExample: rhyolite

Obsidian

If cooling is extremely quick (hours to days)- then no minerals form.

Example: obsidian

Sedimentary Rocks

• Rocks formed from compressed and cemented deposits of sediment.

• Sedimentary rocks are like recycled rocks.

• Contain older rocks and sometimes, fossils.

Formation of Sedimentary Rocks

• Weathering causes rocks to break down; waves, wind, rain

• Pieces of rock accumulate forming sedimentary rock

Formation: 2 ways

• Sediment accumulates- weight from layers above compress the sediment forming rock

• Minerals dissolved in water seep between bits of rock and “glue” them together

Sedimentary Classified as 3 types

1. Detrital – from the Latin word detritus meaning to wear away.

Rocks made from broken rock material. 2. Chemical – when minerals are precipitated

from a solution or left behind from evaporation.

3. Organic – formed from the remains of once-living things.

For thousands, even millions of years, little

pieces of our earth have been eroded--broken down

and worn awayby wind and water. These little bits of our earth are

washed downstream where they settle to the bottom of

the rivers, lakes, and oceans. Layer after layer of eroded earth is deposited on top of each. These layers are

pressed down more and more through time, until the

bottom layers slowly turn into rock.

Examples of Sedimentary Rock

Sandstone- made up of small grains of quartz and feldspar that form in layers

Limestone- made from the mineral calcite which came from the beds of evaporated seas and lakes and from sea animal shells

Examples of Sedimentary Rock

Shale- made of compacted clay

Conglomerate- made of large sediments andsmall particles such as sand and pebbles, medium to large rock fragments.Held together by dissolved minerals

Examples of Sedimentary Rock

Gypsum

Made of sulfate mineral and formed as the result of evaporating sea water in massive prehistoric basins.

Parent Rocks- Sedimentary

Metamorphic• Metamorphic rock is formed from other

rocks as a result of heat, pressure, or chemical processes.

• Parent rock (original rock) undergoes intense heat and pressure within the Earth; as a result, it changes mineral composition and texture.

• Metamorphose or metamorphism – to undergo a change.

Metamorphism

Parent rock/minerals

Metamorphic rockand minerals

Parent Rock Metamorphic

• Limestone

• Mudstone/ Shale

• Marble

• Slate

2 Types of Metamorphic Rock

• Foliated Metamorphic Rocks: mineral grains line up in parallel bands.

• Non – Foliated: mineral grains grow, change and are rearranged but not in layers.

Rock Cycle

1. Magma cools and crystallizes to form igneous rock. 2. Igneous rock undergoes weathering (or breakdown) to form sediment. The sediment is transported and deposited somewhere (such as at the beach or in a delta, or in the deep sea). 3. The deposited sediment undergoes lithification (the processes that turn it into a rock). These include cementation and compaction. 4. As the sedimentary rock is buried under more and more sediment, the heat and pressure of burial cause metamorphism to occur. This transforms the sedimentary rock into a metamorphic rock. 5. As the metamorphic rock is buried more deeply (or as it is squeezed by plate tectonic pressures), temperatures and pressures continue to rise. If the temperature becomes hot enough, the metamorphic rock undergoes melting. The molten rock is called magma. This completes the cycle.