1. Igneous rocks Rocks formed when magma cools
Magma cools slowly inside the Earth.
2. Sedimentary rocks
3. Metamorphic rocks
Rocks formed by the cementing of small grains
Rocks changed by the effect of heat and pressure
Magma cools quickly on the Earth´s surface
Igneous rocks are formed from magma that cools and solidifies
volcano /vɒlˈkeɪnəʊ/
magma
volcano /vɒlˈkeɪnəʊ/
magma
Plutonic rocks are formed when magma cools slowly inside the Earth
Plutonic rocks are heterogeneous rocks with big crystals
Granite is made up of quartz, feldspar and mica
Granite is very hard, so it is used in buildings.
/ˈgrænɪt/
Plutonic rocks are heterogeneous rocks with big crystals
Feldspar
Mica
/ˈsʌɪənʌɪt/
Syenite is pink, similar to granite but with liJle quartz
Plutonic rocks are heterogeneous rocks with big crystals
/ˈɡabrəʊ/
Gabbro is dark and hard
Volcanic rocks are formed when magma cools quickly on the Earth´s surface
volcano /vɒlˈkeɪnəʊ/
magma
Volcanic rocks are homogeneous rocks with small crystals or volcanic glass
/ˈpʌmɪs/
Pumice has a lot of holes or vesicles. It floats in water Vesicular texture
Pumice is used as an abrasive, especially for removing hard skin.
Volcanic rocks are homogeneous rocks with small crystals or volcanic glass
/ˈbasɔːlt/
Basalt is black, with microscopic or Qny minerals of pyroxene and olivine. The ocean floor is basalt
Volcanic rocks are homogeneous rocks with small crystals or volcanic glass
/əbˈsɪdɪən/
It was used by Stone Age people to makes tools such as axes /ˈaksiːz/ and knifes Obsidian is black with a vitreous lustre. It is made up of volcanic glass with no crystals
Rocks formed when sediments are compressed and cemented
Based on the size of the grains, they are classified into 3 groups:
Clasts > 2mm
Clasts < 2mm, but visible to the naked eye
Not visible to the naked eye
Rocks formed when sediments are compressed and cemented
Conglomerate have big, rounded grains, larger than 2mm
Clasts > 2mm, matrix
/kənˈɡlɑmərət/
Rocks formed when sediments are compressed and cemented
Breccia have big and angular clasts
Angular clasts > 2mm
Sandstone has clasts smaller than 2 mm but visible to the naked eye
Rocks formed when sediments are compressed and cemented
/ˈsændstəʊn/
Sand is extracted from sandstone. Very pure sand is used to make glass
Rocks formed when sediments are compressed and cemented
Clay has small grains, not visible to the naked eye /kleɪ/
Clay is used to make bricks, Qles and poJery.
Limestone is not made up of fragments of other rocks
Limestone releases bubbles of CO2 with HCl /ˈkɑːbən daɪˈɒksaɪd/
/ˈlaɪmstəʊn/
Limestone oaen contains fossils or shells
Limestone is used to produce cement and quicklime to paint house exteriors
Fossil fuels are sedimentary rocks that were formed from the remains of organisms that lived millions of years ago
Coal and petrol are our main sources of energy.
Rocks changed by the effect of heat and pressure
FoliaQon
Rocks changed by the effect of heat and pressure
Slate is a dark grey rock, foliated with not visible crystals. Metamorphic rocks rarely contain fossils but slate may contain them
/sleɪt/
Slate splits into sheets
Slate is used to make roofs because it is impermeable and easily broken into thin layers.
Rocks changed by the effect of heat and pressure
Schist is a foliated rock with intense lustre due to the presence of mica Schist splits into sheets
/ʃɪst/
Rocks changed by the effect of heat and pressure
Gneiss has big minerals arranged in bands /naɪs/
Rocks changed by the effect of heat and pressure
Marble is a non-‐foliated metamorphic rock. It releases bubbles with HCl
/ˈmɑːbl/
Marble can be cut and polished to give them more lustre and beauty. They are used to make floors and sculptures