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Transcript
UNIT Work in yo oo k 1 t eb ur no The lithosphere: rocks and minerals Rocks Track 1 Where can we find rocks? The geosphere is the mostly solid, rocky part of the Earth. It has three layers. • The inner most layer, called the core, is made up of metals. • T he middle layer, called the mantle, and the surface, called the crust, are made up of rocks. The crust and the outer layer of the mantle also form the lithosphere. The rocks on the Earth’s crust The crust is made up of solid rock and it is between seven and seventy kilometres thick. Most of the rocks on the crust are on the seabed and are covered by the oceans. The rest form continents and are usually covered by forests, grasslands, crops and cities. Rocks also form large mountain ranges and can be found as loose pieces. These loose pieces are called blocks, gravel or sand. Rocks: where they are found and their characteristics rocks covered by vegetation crust rocks on the seabed mantle 7 km crust mantle core Layers of the geosphere 4 rocks on the surface 70 km Unit 1 What is a rock? Track 2 Rocks are materials that make up the Earth’s crust and mantle. Rocks are a mix of one or various solid substances called minerals. In nature, there are many different types of rocks. They can be distinguished by looking at three characteristics. • Composition. This is the mix of minerals that make up the rock. Some rocks are made up of one mineral and others are made up of various minerals. • T exture. This is the shape and the arrangement of the grains in the rock. Sometimes, the grains are very small and regular. Other times, they are irregular and contain fragments of other rocks. • A ppearance in nature. Rocks can be found in large mountain ranges, in volcanoes and in parallel layers. s re 2 In your own words, explain what rocks and minerals are. 3 Look at the two rock samples below with a partner. Describe each ck Ro sculpt u 1 N ame the three layers of the geosphere. one and write down how they are different. Rocks in parallel layers Texture: fragments of other rocks Rocks in mountain ranges Texture and composition: small and regular grains of three minerals (quartz, orthoclase and mica). 5 Track 3 Minerals Shape fluorite: bi-pyramid Minerals are natural, solid substances that make up rocks. There are many types of different minerals. Each one has got a mix of unique properties. The properties of minerals Minerals are identified by their physical properties. The most important ones are: • Shape. Most minerals appear in rocks as irregular grains or in sheets. Sometimes, they have an almost perfect geometric shape and are called crystals. • Lustre. Lustre is the way the surface of a mineral looks when it reflects light. It is described by its resemblance to the lustre of other materials such as metallic, pearly and silky. • C olour and streak. The colour of some minerals can be seen with the naked eye. Sometimes, the surface is dirty and we have to scratch it to see the true colour. For this reason, when describing minerals we usually use the colour of the streak. This is the colour when the mineral is crushed to a powder. 1 W hat are minerals? 2 What kind of properties are used to identify minerals? 3 W hat do lustre and streak mean? Find out! 6 aragonite: hexagonal prism pyrite: cube Lustre gypsum: silky rose quartz: glassy galena: metallic Colour and streak hematite: grey or red surface, red streak turquoise: blue surface, white streak sulfur: yellow surface, white streak Did you know...? Quartz is one of the most common minerals found on, or in the Earth! Unit 1 Hardness • Hardness. The hardness of a mineral is how difficult or easy it is to scratch. The more difficult it is to scratch, the harder the mineral is. The hardness of a mineral is calculated by scratching it with other minerals on a scale of hardness. Number ten on the scale is the hardest mineral (like diamonds). Number one on the scale is the softest mineral (like talc). • Density. Minerals that contain metals are usually denser. For example, galena, which contains lead, is a very dense mineral. talc: very soft quartz: very hard Density pyrite: very dense sepiolite: not very dense 4 A re the sentences True or False? Correct the false ones in your notebook. 1 M ost minerals appear in rocks as crystals. 2 Crystals have an almost perfect geometric shape. 3 Lustre is the shape of a mineral. 4 Pearly and silky are examples of types of colour. 5 The streak is the colour of a mineral when it is crushed. 6 Diamond is a very soft mineral. 7 Talc is a very hard rock. ! ain Use 5 a) What is density? yo u br r b) How do we calculate the density of a solid object? 6 A nswer the questions in your notebook. 1 W hy do we usually use the colour of the streak when describing minerals? 2 Why is galena a dense material? 3 How do you know the hardness of a mineral? diamond. Why do you think that is? ! ain Use 7 You need a diamond to be able to cut another yo u br r Sci-find esearch a specific mineral. Find R out the following information about your mineral. 1W here on the Earth is it found? 2H ow is it created? 3W hat are its properties? 7 Mined substances Track 4 Extracting substances from the Earth’s crust Deposits are areas of the crust where there are rocks, minerals and other useful substances. There are different ways to extract minerals from a deposit. • Q uarries or open pit mines are holes or cuts that are on or near the surface. • Underground mines are shafts, tunnels and galleries that are deep inside the Earth. • Drilling is when a deep hole is made. A pipe is then put in the hole to extract gas or liquids, such as oil or water. Extracting substances Extraction in mines Extraction by drilling 1 M atch the sentence halves in your notebook. 1 Deposits are… a) … near the Earth’s surface. 2 Quarries or open pit mines are… b) … deep in the ground. 3 Underground mines are… c) … when a pipe is put in a deep hole to extract gas or liquids. 4 Drilling is… d) … areas where there are rocks, minerals and other useful substances. 2 Listen to Freddie talking about his job and answer the questions. Track 5 8 What is Freddie’s job? Where in Spain does Freddie work? Why does Freddie wear safety equipment? What natural material does Freddie work with? d dergroun Un 1 2 3 4 mals an i Unit Track 6 How do we use mined substances? 1 Mined substances clay Building materials Blocks of granite, limestone and basalt are used to build walls. Sheets of slate are used to make floors or roofs. Clay is used to make pottery and other ceramic items. granite slate Building materials Decorative materials Marble is used to make sculptures and coatings for floors and walls. Some minerals, such as diamonds, rubies and sapphires, are used to make jewellery. They are called gemstones. gold marble Industrial materials Cement is made by spraying and baking clay and limestone. Glass is made from a mineral called quartz. Metals are made from minerals called metal ores. For example, copper is extracted from chalcopyrite and iron is extracted from hematite. Energy sources Coal, oil and natural gas are fuels that are extracted from rocks. They are formed from the organic remains of prehistoric plants and animals. For this reason they are called fossil fuels. Uranium is a substance that is used in nuclear power plants to make electricity. It is extracted from a mineral called pitchblende. rubies and diamonds Decorative materials cement aluminium copper iron glass Industrial materials natural gas coal petrol Energy sources 3 Make a list of all of the substances mentioned in the text. Write down a use for each one. 4 W hat are fossil fuels and how are they formed? 5 W hich mined substance is used to make... 1 ... electricity? 2 ... glass? 3 ... floors and roofs? 9 Apply your skills! Project Volcanoes Volcanoes are mountains or hills that have an opening. When they are active, ash, gas and hot magma escape from inside the Earth. These eruptions can be spectacular but also dangerous! atch the words to letters a-c. 1 M 1 ash 3 magma b 2 eruption a 2 Work in small groups to simulate a volcanic eruption. c You will need: • • • • 10 a small wooden board modelling clay a small plastic bottle red food colouring • baking soda • vinegar • a cloth or paper towels (just in case you need to clean up!) Step 1 sing modelling clay, model the shape of a volcano. Make U it big enough to fit the plastic bottle inside! Then, put your volcano on the wooden board. Step 2 aint your volcano and your board. Use photos to help P you choose your colours and textures. Step 3 ut off the top part of your plastic bottle and put it inside C your volcano. Step 4 ut the vinegar and the red food colouring inside the P plastic bottle. Step 5 inally, add a couple of teaspoons of baking soda to the F mixture and watch your volcano erupt! Check what you know! ok o b te Work in your no My Word list Rocks core/crust/mantle geosphere lithosphere Minerals 1 Trace the picture below. Mark the crust, the mantle and the inner and outer core. colour density hardness lustre shape streak Mined substances deposits Uses of mined substances nswer the following questions in your notebook. 2 A 1 What are rocks made of? 2 What three characteristics distinguish rocks? 3 What are loose pieces of rock called? 3 a ) Find five mineral properties in the word snake. pe sh a densitystreaklustr eha r d n ess building: • basalt/limestone • clay/granite/slate decorative: • gemstones energy sources: • coal/fossil fuel/ natural gas/oil/ uranium industrial: • cement • glass • metal ores b) Write a short definition for each property. 4 a) Name three substances we use to produce industrial materials. b) Name three substances used to produce energy. c) Which are the best substances to make decorative materials? 11