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 GraniteBasalt

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 weeks Minerals do not have time to grow Grains are very small – above ground - extrusive Example: 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 away by 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 and small 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 rock and 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.