Part 2 Mineral types and characteristics

Minerals : 

Minerals

Minerals : 

Minerals We can not make it through life without minerals Nearly every manufactured product we use in a typical day contains materials obtained from minerals Lead in your pencil is graphite Most body powders contain talc Dentist’s drill bits contain diamonds Main ingredient in windows is quartz

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Minerals What is a mineral? It is a naturally occurring inorganic solid with an orderly crystalline structure and a definite chemical composition For something to be a mineral it must have five characteristics

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Minerals The first characteristic: It must be naturally occurring A mineral forms by natural geographic processes So, man made minerals such as synthetic diamonds and rubies are NOT minerals

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Minerals The Second Characteristic It must be a solid substance Minerals are solids within the temperature ranges that are normal for Earth’s surface Mercury is an element, yet it is a liquid. Why would it still be an element if it is a liquid? The mercury we see is actually extracted from a cinnabar (HgS) which is solid at room temperature

Mineral : 

Mineral The Third Characteristic It must have an orderly crystalline structure Minerals are crystalline structures which means their atoms or ions are arranged in an orderly and repetitive manner Opal (a gemstone) has the same elements as quartz but is not a mineral. Why? It does not have an orderly internal structure!

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Minerals The Fourth Characteristic It has a definite chemical composition Most minerals are made up of two or more elements A few, such as gold and silver contain just one element When they consist of two or more elements the elements always form in the same proportion Quartz is SiO2. It always forms with one atom of Silicon and two atoms of oxygen

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Minerals The Fifth Characteristic It is generally considered inorganic By “inorganic” we mean “not living”. Living things are NOT minerals Sugar, even though it is a crystalline solid, is not considered a mineral because it comes from a living thing By “generally inorganic” we mean that sometimes inorganic materials come from living things Some marine animals secrete inorganic compounds such as calcium carbonate which we see as shells or coral reefs. Calcium carbonate is considered a mineral

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Minerals How do minerals form? Minerals form nearly everywhere on Earth Some form deep in the crust, even in the mantle, where temperature and pressure is very high Some form in warm, shallow ocean waters Some form on at or near Earth’s surface when existing minerals are exposed to weathering Some form when rocks are subject to changes in temperature or pressure

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Minerals There are four major processes by which minerals form Crystallization from magma Precipitation Changes in pressure and temperature Formation from hydrothermal solutions

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Minerals Crystallization from Magma Magma is molten rock deep within the earth As the magma cools, elements combine to form minerals The first mineral to form are usually rich in iron, calcium, and magnesium Later other minerals rich in sodium, potassium, and aluminum form

Minerals : 

Minerals Precipitation The water in Earth’s lakes, rivers, ponds, oceans, and beneath its surface contain many dissolved substances When the water evaporates, some of the dissolved substances can react to form minerals Changes in temperature may also cause dissolved material to precipitate out of the water Two common minerals formed this way are limestone and Halite

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Minerals Pressure and Temperature Some minerals, such as talc and muscovite, form when existing minerals are subject to changes in pressure and temperature An increase in pressure can cause minerals to recrystallize Changes in temperature can cause minerals to become unstable causing new minerals to form which are stable at the new temperature

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Minerals Hydrothermal Solutions A hydrothermal solution is a very hot mixture of water and dissolved substances. Temperatures can be between 100 and 300 degrees Celsius! When these solutions come into contact with existing minerals, chemical reactions take place to form new minerals Or, when they cool, they may combine to form other elements such as quartz and pyrite

Minerals : 

Minerals Mineral Groups Over 3800 minerals have been named New ones are identified and named every year Common minerals, along with the thousands of others that form Earth, can be classified into groups based on their composition

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Minerals The most common groups The Silicates The Carbonates The Oxides The Sulfates and Sulfides The Halides The Native Elements

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Minerals The Silicates Silicon and Oxygen combine to form a structure called the silicon-oxygen tetrahedron It consists of one silicon atom and four oxygen atoms

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Minerals Quartz is the most common silicate mineral One like in the picture can contain millions of silicon-oxygen tetrahedra Mica is another example. In Micas the tetrahedra form sheets

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Minerals Different mineral can form from the same elements when they form under different kinds of temperatures and pressure How the atoms combine determine the kind of minerals that form

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Minerals How the atoms connect creates unique characteristics to the minerals such as cleavage, shape, and hardness

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Minerals As long as there is room to grow, minerals will continue to grow

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Minerals The last five slides have all been silicates, formed from silicon and oxygen atoms into different kinds and shapes of minerals

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Minerals The Carbonates The second most common mineral group Carbonates contain carbon, oxygen, and one or more other metallic minerals

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Minerals Calcite is the most common carbonate mineral Dolomite is another carbonate mineral and contains magnesium and calcium Limestone and marble are carbonate minerals

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Minerals Oxides Minerals that contain oxygen and one or more other elements, which are usually metals

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Minerals Common oxides are Corundum Rutile Hematite

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Minerals Sulfates and Sulfides Minerals that contain the element sulfur

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Minerals Common Sulfates are: Anhydrite Gypsum They form when mineral rich waters evaporate Common Sulfides are: Galena Pyrite They form from thermal or hot water solutions

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Minerals Halides Minerals that contain a halogen ion plus one or more other elements

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Minerals Common Halides are Halite Table Salt Fluorite Forms when salt water evaporates

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Minerals Native Elements A group of minerals that exists in relatively pure form Only one kind of element makes up a native element mineral

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Minerals Some native elements minerals are Gold Silver Copper Sulfur Carbon Native forms of carbon are graphite and diamonds Native elements form from hydrothermal solutions