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Minerals ROCK! ©McGill University 2010 This presentation was made possible with funding from the PromoScience programme of NSERC
Minerals ROCK!
©McGill University 2010
This presentation was made possible with funding from the PromoScience programme of NSERC
Minerals
Why are they important?
©McGill University 2010
Minerals are important because:
We use them in everyday life!• Glass (Quartz)
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www.public-domain-image.com
Minerals are important because:
We use them in everyday life!• Glass (Quartz)
• Lead in pencil (Graphite)
©McGill University 2010
www.public-domain-image.com
Minerals are important because:
We use them in everyday life!• Glass (Quartz)
• Lead in pencil (Graphite)
• Toothpaste (Fluorite)
©McGill University 2010
www.public-domain-image.com and www.wikipedia.org. Public domain.
Minerals are important because:
We use them in everyday life!• Glass (Quartz)
• Lead in pencil (Graphite)
• Toothpaste (Fluorite)
• Coins and wiring (Chalcopyrite, from whichmost copper metal is made)
©McGill University 2010
www.public-domain-image.com and www.wikipedia.org. Public domain.
Minerals are important because:
We use them in everyday life!
• Glass (Quartz)
• Lead in pencil (Graphite)
• Toothpaste (Fluorite)
• Coins and wiring (Chalcopyrite, from whichmost copper metal is made)
• White paint (Rutile and Ilmenite)
©McGill University 2010
www.public-domain-image.com and www.wikipedia.org. Public domain.
Minerals are important because:
We use them in everyday life!• Glass (Quartz)
• Lead in pencil (Graphite)
• Toothpaste (Fluorite)
• Coins and wiring (Chalcopyrite,from which most copper metalis made)
• White paint (Rutile and Ilmenite)
• Make-up (Talc, Muscovite)
©McGill University 2010www.public-domain-image.com, www.wikipedia.org, and wpclipart.com. Public domain.
Minerals are important because:
We use them in everyday life!• Glass (Quartz)
• Lead in pencil (Graphite)
• Toothpaste (Fluorite)
• Coins and wiring (Chalcopyrite, from whichmost copper metal is made)
• White paint (Rutile andIlmenite)
• Makeup (Talc, Muscovite)
• Jewellery (Gold, Silver,Platinum…)
©McGill University 2010www.public-domain-image.com, www.wikipedia.org, and wpclipart.com. Public domain.
Minerals
• How many minerals are there in the world? – Over 4200 different minerals!
– But only 100 are common
• Ones that are more rare include:
©McGill University 2010Gold Silver
www.wikipedia.org. Public domain.
What is a mineral?
• A mineral must have…– A crystalline structure
– A definite chemical composition
• A mineral must be…– Formed by geological
processes
– Inorganic
– Solid
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What does this mean?
• A mineral must have…. – A crystalline structure
• Minerals are made of molecules, and a crystalline structure is a repeated pattern of those molecules.
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Crystalline structure (i)
– The crystalline structure explains the geometric shapes that crystals take on when they grow under favourable conditions .
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Crystalline structure (ii)
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• Crystals will keep growing…
Crystalline structure (iii)
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… and growing forever, as long as they have the chemical elements and the environmental conditions necessary.
Minerals are formed by geological processes
– They can’t be man-made so steelis not a mineral.
©McGill University 2010www.wikipedia.org. Public domain.
Minerals are inorganic
– Not living and not made by living things.
– Shells are not a type of mineral but they they are made of solid materials (biominerals) similar to some inorganic minerals.
©McGill University 2010Redpath Museum
A mineral is solid
– Minerals may be dissolved in liquids but they themselves are not liquid.
©McGill University 2010www.wikipedia.org
Is ice a mineral? (i)
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www.usgs.gov. Public domain.
Is ice a mineral? (ii)
• YES!!– Inorganic
– Solid
– Crystalline structure
– As long as it is naturallyoccurring, ice isconsidered a mineral. Ice in your ice-cube trayis not naturally occurring: ice in a glacier is.
©McGill University 2010www.wikipedia.org. Creative Commons Attribution-Share Alike 3.0 Unported license
Is water a mineral? (i)
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www.usgs.gov. Public domain.
Is water a mineral? (ii)
• NO!– Inorganic
– Naturally occurring
– But it is a LIQUID and
has NO CRYSTALLINE
STRUCTURE
©McGill University 2010
www.usgs.gov. Public domain.
How are minerals formed?
• Many minerals crystallize from liquids, principally magma/lava (molten rock), hot waters (e.g., geysers), or oceans.
• Others are formed when rocks are re-buried below the Earth’s surface and exposed to high pressure and temperature. The minerals become unstable and they exchange chemical elements. This forms new minerals.
©McGill University 2010
Why are minerals found in large quantities in some places and not
others?
• The Earth’s surface is made up of plates that move. “Plate tectonics” describe this motion.
• Together with erosion, plate tectonics concentrate some of these elements in bodies of rocks that can be mined.
• Plate tectonics are the Earth's giant "recycling engine“.
Plate tectonics
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www.wikipedia.org. Public domain.
The world’s main plates
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www.wikipedia.org. Public domain.
Types of plate boundaries (i)
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• Transform boundaries: plates grind past each other along a transform fault (e.g. San Andreas fault).
www.wikipedia.org: public domain or licensed under a Creative Commons Attribution Share-Alike 3.0 License
Types of plate boundaries (ii)
©McGill University 2010
• Divergent boundaries: plates slide away from each other (e.g., mid-oceanic ridges).
Wikipedia.org, NASA: public domain
Types of plate boundaries (iii)
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• Convergent boundaries: plates slide towards each other. – If one plate moves
underneath the other, it forms a subduction zone. Deep marine trenches, volcanoes, and some mountain chains (e.g., the Andes) form in these areas. The Puerto Rico trench. Wikipedia.org, USGS: public domain
North American plate
Caribbean plate
Types of plate boundaries (iv)
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• Convergent boundaries (cont’d): – If the two plates collide and both contain
continental crust, they form a continental collision. Some mountains (e.g., the Himalayas) form this way.
Wikipedia.org, USGS: public domain
Rocks
©McGill University 2010www.wikipedia.org. Public domain.
Rocks
• Rocks are made of minerals
• Granite is a rock made up of three main minerals:– Feldspar
– Quartz
– Mica
©McGill University 2010
A world of rocks
• There are 3 main types of rocks:
– Igneous rocks
– Metamorphic rocks
– Sedimentary rocks
©McGill University 2010www.wikipedia.org and www.usgs.gov. Public domain.Redpath Museum
Igneous rocks
©McGill University 2010www.wikipedia.org. Public domain.
• Deep in the earth the temperatures are so high that materials, including minerals, melt and form magma.
• When the magma cools, it becomes rock.
• E.g., granite, basalt.
Metamorphic rocks (i)
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• When rocks are re-buried below the Earth’s surface and exposed to high pressure and temperature, the minerals become unstable and they exchange chemical elements.
• This forms new minerals. This may also cause some grains to grow and others to shrink.
Metamorphic rocks (ii)
©McGill University 2010
GneissSlate
www.usgs.gov. Public domain.
• This process produces new types of rocks that are different in composition and texture from the originals.
• E.g., bands of minerals are folded in gneiss.
Sedimentary Rocks
©McGill University 20101 www.usgs.gov. Public domain.
• Sediments come from the erosion ofpreviously existing rocks, dissolvedminerals that precipitate out ofsolution, or the remains of plantsand animals.
• Loose sediment accumulates in beds and, over time, becomes compressed and cemented together.
• These types of rocks areusually layered.
• E.g., limestone and sandstone.
Limestone2
Sandstone1
2 Redpath Museum.
The Rock Cycle: Always Recycling
©McGill University 2010www.wikipedia.org. Public domain.
1. Magma2. Crystallization3. Igneous rock4. Erosion5. Sedimentation6. Sedimentary rock7. Tectonic burial8. Metamorphic rock9. Melting of rock
and minerals
Crystals
©McGill University 2010
Quartz
Halite
What is the difference between minerals, crystals, and rocks? (i)
– Minerals are made up of regularly arranged atoms.
– Minerals grow as distinct objects called crystals.
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Agate (a form of the mineral quartz)
Crystals
– Crystals are made up of only one type of mineral.
– A crystal’s atoms, ions, or molecules are arranged in an orderly, repeating pattern.
– Crystals can have different shapes, depending on how the groups of atoms are arranged.
©McGill University 2010
Quartz crystal and penny
What is the difference between minerals, crystals, and rocks? (ii)
Crystals
– A rock is a mass of many crystals from one or several minerals.
– Granite is a rock made of 3 main minerals:
• Feldspar
• Quartz
• Mica
©McGill University 2010
What is the difference between minerals, crystals, and rocks? (iii)
How are crystals formed?
• Most come from a liquid evaporating (e.g., salt) or magma cooling.
• Minerals in the liquid precipitateout as the liquid evaporates. As more minerals precipitate out, the crystal grows in size.
• Crystals can grow forever, as long as they have the chemical elements and the environmental conditions necessary.
©McGill University 2010
Mineral Identification (i)
• The two most important properties that scientists use to identify minerals are:– chemical composition (e.g., via microprobe
analysis)
– crystal structure (e.g., via X-ray diffraction analysis), which is reflected in the mineral's crystal symmetry and shape
©McGill University 2010
Mineral Identification (ii)
• Other properties that scientists use to help identify minerals include:– Colour – Luster (how the surface reflects light)– Streak (the mark it leaves on a ceramic plate)– Hardness – Magnetism– Crystal system (crystal shape and the way in
which the crystals are arranged)
©McGill University 2010
Acknowledgments
• Scientific consultation– Dr. Jeanne Paquette (Earth and Planetary
Sciences)
– Dr. Peter Tarassoff (Redpath Museum)
• Concept, design, and production: – Jacky Farrell
– Elizabeth Miazgy
– This presentation was made possible with funding from the PromoScience programme of NSERC
©McGill University 2010
