I Can.. Identify the differences between a mineral and a rock. What is a mineral?

Transcription

1 I Can.. Identify the differences between a mineral and a rock. What is a mineral? A mineral: o Is a Inorganic solid formed in nature (Inorganic -- not living or ever been living. Which means that it is not formed by plants or animals) o Has a fixed chemical composition o Has distinctive physical properties o Has a Crystalline structure (has an orderly arrangement of its atoms) 1

2 Crystals: Minerals with some solid, geometric shape to them are called crystals. They are produced by a repeating pattern of atoms that is present through-out the mineral. Crystals can be made from different elements: (ex: diamonds are made from the element Carbon) (salt is made from the element Sodium and Chlorine) Crystals: A crystal s shape is determined by the arrangement of the atoms within the crystal. A crystal s color is determined by the elements that are mixed in it. Crystals are not just what we think of as jewelry. You actually eat many different types of crystals! ( such as salt, sugar, baking soda) 2

3 Minerals are more common than you think Currently, about 4,000 minerals have been identified, and 50 to 100 new minerals are discovered each year!! We use them in our everyday households such as metal pots and pans, salt shakers, dishware, and even glassware!!! How do minerals form? They form in several ways: 1. From melted rock inside the Earth called magma As it cools the atoms combine in orderly patterns to form minerals 2. From magma that reaches Earth s surface, called lava. As it cools the atoms combine in orderly patterns to form minerals 3. Evaporation of dissolved minerals 4. From precipitation *water in the atmosphere can hold the dissolved minerals that have evaporated. 3

4 9/17/15 Properties of Minerals include: Color Luster Streak Hardness Cleavage & Fracture Density Specific Gravity Special Properties Color: Not Mineral Specific Color is the LEAST reliable way to classify a mineral. A certain mineral may form in many different colors due to any chemical impurities it may contain that will affect the mineral s color! *See examples of Quartz below:(a) clear Quartz (B) Blue Agate, (C) Rose Quartz, & (D) purple Amethyst. Purple due to small amounts of Iron 4

5 9/17/15 Other factors can also affect a mineral s color. Weathering changes the surface of a mineral which slightly affects the color. Because color alone is unreliable, geologists rarely identify a mineral just on its color. To identify most minerals, they must use several properties. Luster: (shininess) Describes how light reflects off of the surface of a mineral. You might describe diamonds as sparkly or pyrite as shiny. But mineralogists have special terms to describe luster. They first divide minerals into metallic and non-metallic luster. Metallic Non-metallic 5

6 9/17/15 IV. Shininess (continued) Luster (or shininess) can be either: Metallic shines like metal Non-metallic dull, pearly, earth (A) Diamonds have an adamantine luster (transparent & highly reflective. (B) Kaolinite is a clay with a dull or earthy luster. (C) Opal s luster is greasy. (D) Chalcopyrite has metallic luster. (E) Stilbite has a resinous luster. (F) The white ulexite has silky luster. (G) Sphalerite has a submetallic luster. (H) Jade is a mineral with a waxy luster. of the powder of a mineral. To Streak: Is dotheacolor streak test, you scrape the mineral across an unglazed porcelain plate. NOTE: The color of the streak often differs from the color of the larger mineral sample, Different minerals may be the same color, but they may have a different color streak! The color of a mineral may vary BUT streak does not! 6

7 Cleavage & Fracture Describes how different types of minerals break. Cleavage is the tendency of some minerals to break along smooth, flat surfaces. Fracture is the tendency of some minerals to break unevenly along curved or irregular surfaces Mica Hardness: A mineral s resistance to being scratched. Minerals that are not easily scratched are considered hard minerals and those that are easily scratched are considered soft minerals. This is tested using the Mohs Hardness Scale. You test the hardness of an unknown mineral by scratching its surface with a mineral of a known hardness. 7

8 As you can see, diamond is a 10 on the Mohs Hardness Scale. Diamond is the hardest mineral; no other mineral can scratch a diamond. Quartz is a 7. It can be scratched by topaz, corundum, and diamond. Quartz will scratch minerals that have a lower number on the scale. Fluorite is one. Suppose you had a piece of pure gold. You find that calcite scratches the gold. Gypsum does not. Gypsum has a hardness of 2 and calcite is a 3. That means the hardness of gold is between gypsum and calcite. So the hardness of gold is about 2.5 on the scale. A hardness of 2.5 means that gold is a relatively soft mineral. It is only about as hard as your fingernail! Oohhhhhh Diamonds!... Diamonds are the hardest known mineral (10 on Mohs Hardness Scale) They are formed very deep in the Earth and at great pressure. It takes 250 tons of Earth to obtain a 1.00 Ct Diamond! It takes 1405 degrees of heat to burn a Diamond! Only Diamonds can Scratch or Polish another Diamond! Diamonds come in wonderful fancy colors like, Pink, Blue, Green, Champagne, Black, Chocolate, Yellow, Red, Gray, and even Purples! (Here is the famous HOPE diamond, which is blue!!) 8

9 9/17/15 Did You Know? The largest diamond in the world is the Cullinan diamond weighing 3,106 carats! It was cut into 105 separate diamonds. Oohhhhhh Diamonds!... If Diamonds are the hardest mineral, what is the second hardest mineral according to the Mohs Hardness Scale? Corundum!!!! Which is the mineral name for ruby and sapphire. 9

10 Density Density describes how much matter is in a certain amount of space. Substances that have more matter packed into a given space have higher densities. Mass is a measure of the amount of matter in an object. The amount of space an object takes up is described by its volume. The density of an object depends on its mass and its volume. Density can be calculated using the following formula: Density= Mass/Volume Different minerals have different densities. Special Properties Some properties are special because they only belong to a few types of minerals! *Magnetite *Uraninite *Some minerals have a distinctive smell: Sulfur (smells like rotten eggs) 10

11 GEMS are rare minerals that can be cut and polished, giving them a beautiful appearance. Ideal for jewelry Are rare and are therefore valuable Are created by tremendous amounts of heat and pressure, deep in the Earth s mantle It takes a certain kind of volcanic eruption to bring diamonds close to the surface Ores A mineral is called an ore if it contains enough of a useful substance that it can be sold for a profit. Metals that people use, such as: Iron used to make steel comes from Hematite Lead for batteries comes from Galena Magnesium in vitamins comes from Dolamite In order to obtain these ores, they must be mined 11

12 Minerals Review. Now watch the Mineral s Review Quiz. See if you can classify the following items correctly. (Use your half-slip we pasted in your ISN.) What is a Mineral? 12

13 What is a mineral? A mineral is a naturally formed, inorganic solid that has a definite crystalline structure. It has to pass the SNIFC test.. Solid Cannot be a liquid or a gas Naturally Occurring Found in nature, not man- made Inorganic Is not living nor has ever been living Fixed chemical composition Has a definite chemical formula, most are formed from two or more elements, but some minerals consist of one element ex. Au Crystalline structure A definite structure in which atoms are arranged in a geometric pattern 13

14 Questions to ask yourself when determining if an item is a mineral or not: Is it non- living material? Is it a solid? Is it formed in nature? Does it have a crystalline structure? Wood 14

15 Gold Fossil 15

16 Topaz Bones 16

17 Granite Quartz 17

18 Pearls Talc 18

19 Icebergs Diamond 19

20 Coal Rock Salt 20

21 And the answers are How did you do?... Minerals Non- Minerals a) Gold b) Topaz c) Quartz d) Talc e) Iceberg* f) Diamonds a) Wood - once living b) Fossils once living c) Bone - living material d) Granite - intrusive igneous rock e) Pearls made by oysters f) Coal - Sedimentary rock g) Rock Salt Sedimentary rock FYI: According to the IMA (International Mineral Association) ice is listed as a mineral! Can you name all eight physical properties of minerals? Quick Check.. Color Luster Streak Hardness Cleavage & Fracture Density Specific Gravity Special Properties 21

22 I Can.. explain how the three different types of rocks are formed. So What Exactly is a Rock?? A rock is a naturally occurring solid mixture of one or more minerals and organic matter. *organic = living Rocks go through a cycle, meaning they are constantly changing into different forms. 22

23 Classifying Rocks Each class of rock can be divided further and classified based on differences in the ways rocks form. Igneous rock can be divided again based on whether the magma from which it forms cools is on the Earth s surface or underneath the ground. Sedimentary and metamorphic rocks are also divided into smaller groups. Scientists study rocks in detail using two important criteria: composition and texture. What determines a rock s composition? The minerals that a rock contains determine the Composition which is the combination of substances that are contained in rock. (ex: a rock made mostly of quartz will have a composition similar to Quartz. But a rock made of 50% quartz and 50% feldspar will look much different than that of pure Quartz) Quartz & Feldspar Quartz 23

24 9/17/15 Rocks have Quality!!! Texture is the size, shape, and position of the rock s grains. It s what determines the quality of a rock. Texture provides clues as to how and where the rock actually formed and reveals the process that formed it. Siltstone Fine grained Sandstone Medium grained Conglomerate Coarse-grained 3 Major Types of Rocks Igneous Rocks Metamorphic Rocks Sedimentary Rocks 24

25 Look at these pictures of rocks. How are they different? How are they the same? Igneous Rocks Igneous Rocks are called fire rocks The word ignis means fire : 25

26 How are igneous rocks formed? Name two places where igneous rocks form 26

27 Igneous rocks are made either underground (intrusive) or above ground (extrusive). 27

28 Igneous Rocks fire rocks Underground: melted rock, called magma, cools slowly and solidifies to become igneous rocks. Igneous Rocks fire rocks Above ground: volcanoes erupt, bringing the magma to the earth's surface, it is called lava. The lava cools and becomes igneous rocks. 28

29 What determines crystal size? 29

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31 What s the difference between extrusive and intrusive igneous rocks? form on or near the surface (small crystals) form below the surface (large crystals) 31

32 Characteristics used to classify igneous rocks Characteristics used to classify igneous rocks 32

33 Characteristics used to classify igneous rocks Characteristics used to classify igneous rocks Helps determine the color of the melted rock. This depends on the materials that were available as the rock was forming. 33

34 Igneous Rocks fire rocks Granite Pumice Basalt Obsidian Pumice is cool! It can float! u Pumice used for cleaning and polishing 34

35 Uses of Igneous Rocks Statues and Public Buildings - Uses of Igneous Rocks Cobblestone streets and Granite kitchen countertops Granite 35

36 Sedimentary Rocks Sandwich rocks Sedimentary Rocks sandwich rocks For millions of years, little pieces of our earth (called particles) have been broken down by wind and water. 36

37 Sedimentary Rock sandwich rocks These little bits of our earth are washed to the bottom of the rivers, lakes, and oceans where they settle and are compressed together over time. Sedimentary Rock sandwich rocks Many layers of small pieces of earth collect on top of each other in layers. These layers are pressed down more and more until the bottom layers slowly turn into hard rock. 37

38 4 Steps in which Sedimentary Rocks are Formed Wind and water break down the earth Bits of earth settle in lakes and rivers Layers are formed and build up Pressure and time turn the layers into rock There are 4 main processes needed to form sedimentary rock: Step 1: EROSION (par8cles wash away) Forces of running water, wind, or ice that loosen & carry away fragments of rock Can you see the sediment moving in the water? Have you ever seen sediments being moved during a hard rain? 38

39 There are 4 main processes needed to form sedimentary rock: Step 2: DEPOSITION (deposits - drops down) Sediments se@le out of the water or wind carrying them & se)le to the bo@om of a lake or ocean. Sediments move down the sloped land & sefle at the bofom. Over 8me these sediments layer up. There are 4 main processes needed to form sedimentary rock: Step 3: COMPACTION (smashed together) Process that presses sediments together. Thick layers of sediment build up over Ime & weigh down the layers compac.ng them. 39

40 Those smashed sediments can form into layers like the ones shown above. There are 4 main processes needed to form sedimentary rock: Step 4: CEMENTATION (glued together) Dissolved minerals seep into spaces between paricles (sediments) & then crystallize as they harden. 40

41 Sedimentary Rock These 4 processes can take thousands to millions of years to form. The most common form of sedimentary rock on Earth is Shale. It covers about ¾ of the land s surface. 41

42 Most sedimentary rocks are made of pieces: of other rocks. Remains of living things. Minerals that are dissolved in watery solutions Made from pieces of other rocks 42

43 Made from remains of living things (fossils). Made from minerals that are dissolved from watery solutions. Rainwater makes it way to the oceans dissolving minerals along the way. Ex: rock salt 43

44 Types of Sedimentary Rocks Sandstone Limestone Conglomerate Shale Metamorphic Rocks changing rocks 44

45 Metamorphic Rock changing rocks Metamorphic rocks are rocks that have "morphed" or changed into another type of rock. The word metamorphic means changed form. These rocks were once either igneous or sedimentary rocks. Metamorphic Rock changing rock They are formed from extreme heat and tons of pressure 45

46 Two types of texture in Metamorphic Rock: Foliated Contains minerals that have been aligned by pressure and almost look like pages in a book. Ex: Slate Nonfoliated Do not have distinctive layers and Are made of only a few minerals: Metamorphic Rock changing rock Most rocks will melt at temperatures higher than 1,000 degrees Celsius_. 46

47 Under pressure and Feeling the Heat!!! (Horseshoe shaped) Metamorphic rock is like plastic!! When rocks metamorphose under high temperature and pressure, they become plastic and can be easily deformed. The largest range of exposed metamorphic rock in the world is the Canadian Shield. It is the source of more than 70% of the minerals mined in Canada. Texture of Metamorphic Rock Foliated metamorphic rock: The hot minerals become aligned by pressure and almost look like pages in a book. *banded 47

48 Texture of Metamorphic Rock Nonfoliated metamorphic rock: Do not have distinctive layers and are made of only just a few minerals. Types of Metamorphic Rocks Schist Gneiss 48

49 Metamorphic Rock changing rock Marble Slate Quartzite I Can.. identify the major processes that explain the rock cycle. 49

50 The Rock Cycle Rocks and the Rock Cycle Remember rocks go through a cycle, meaning rocks are always changing. New rocks continually form from old rocks and old rocks get recycled. We call this process process the Rock Cycle. This process is similar to other cycles we know of such as the water cycle, carbon cycle, and nitrogen cycle. 50

51 The Value of Rock Rock has been an important natural resource for as long as humans have existed. Ancient and modern civilizations have used granite, limestone, marble sandstone, slate and other rocks as construction materials. Rock is also an important ingredient in concrete and plaster, both of which are commonly used in construction. Processes That Shape the Earth Certain geological processes make and destroy rock. These processes have shaped the features of our planet. These processes also influence the type of rock that will be found in certain areas. 51

52 Processes That Shape the Earth include: Weathering Erosion Deposition Lithification. Weathering, Erosion, and Deposition The process in which water, wind, ice, and heat break down rock is called weathering. Weathering is important because it breaks down rock into fragments from which sedimentary rock is made. Wind, water, ice, and gravity then transports soil and sediment from one location to another through a process called erosion. As the process continues sediments are later moved by erosion and eventually dropped and comes to rest in a process called deposition. 52

53 Processes That Shape the Earth, continued As rock particles and organic matter are eroded to a place of deposition and are covered by additional particles, eventually the weight from above will start a process called lithification. Lithification involves two steps: A) compaction --squeezes out the fluids and space that exist between the particles. B) cementation--- results when the fluids that are squeezed out are replaced with minerals that were in the fluids. **Once cementation occurs, the new sedimentary rock has been formed From Sedimentary Rock to Metamorphic Temperature and pressure are important: If the heat and pressure are high enough, the rock can change into metamorphic rock. If the rock gets hot enough to melt, this creates the magma that eventually cools to form igneous rock. 53

54 How the Cycle continues: Rock that is buried beneath the earth s crust is eventually uplifted to the surface thanks to movements within the Earth. This process is called uplifting. As Erosion continues to chip away at the Earth s surface, the rock that has been uplifted will eventually be exposed to the Earth s surface. When uplifted rock reaches the Earth s surface, weathering, erosion, and deposition begin to help the cycle begin all over again. What happens to older rock????? As new rock is pushed up towards the surface, older rock is pushed down!!. 54

55 Rock formation does not have to go through a direct pattern. Understand that sedimentary rock can become igneous rock just as metamorphic rock can become sedimentary rock!! Remember: The rock cycle is not an overnight process. It may take millions to tens of millions of years for each process in the rock cycle to occur!!!. The Rock Cycle in Action: 55