What Are Minerals?

1. What Are Minerals? • Minerals – a naturally occurring, inorganicsolid that has a crystalstructure and a definite chemicalcomposition

2. What 5 Characteristics Does a Mineral Have to Have? A mineral must be: • Naturally Occurring • Inorganic • Solid • Crystal Structure • Definite Chemical Composition

3. What Does It Mean to Be Naturally Occurring? • A mineral must occurnaturally • Cement, brick, steel, and glass all come from substances found in Earth’s crust but they are manufactured by people

4. How Can Something Be Inorganic? • Inorganic – the mineral cannot arise from materials that were once part of a living thing • Ex. Coal is NOT a mineral because it is made up the remains of plants and animals

5. What kind of pattern must a mineral have? • A mineral must have a crystal structure – a repeating pattern of a mineral’s particles that forms a solid. • Faces – a crystal’s flat side that meets at sharp edges and corners

6. What kind of composition must a mineral have? • A mineral must have a definite chemical composition – it always contains certain elements in definite proportions; most minerals are compounds Cinnabar – composed of the elements Mercury and Sulfur

7. What Is the Difference Between an Element and a Compound? • Element – a substance composed of asinglekind ofatom. Ex. Hydrogen • Compound –Twoor moreelementscombinedso that the elements no longer have distinctproperties Ex. Water H20

8. What are the 2 groups of minerals? • All minerals can be divided into Silicates and Non-silicates • Silicates= Siand O are the two most abundant elements in the earth’s crust.

9. SiO4: One Silicon,Four Oxygen

10. What are the Non-Silicates? 4% of the Earth’s Crust Carbonates, Halides, native elements.

11. Slide 10 cont’d more non-silicates Oxides>>> sulfates>> sulfides>>

12. Properties: Density Crystal Shape Cleavage and Fracture Special Properties Hardness Color (this can vary) Streak Luster How Do You Identify Minerals?

13. How Do You Determine a Mineral’s Hardness? • Friedrich Mohs invented a test to describe and compare the hardness of minerals • Mohs Hardness Scale • Ranks ten minerals from softest to hardest

14. How Does the Mohs Scale Work? • Gypsum (2) will scratch talc (1), calcite (3) will scratch gypsum (2), fluorite (4) will scratch calcite (3), etc.

15. To remember the Mohs scale try remembering this phrase: The Geologist Can Find An Ordinary Quartz, (that) TouristsCall Diamond!

16. What Is a Streak Test? • The streak of a mineral is the color of its powder • The streak color and the mineral color are often different • To test: rub a mineral against an unglazed tile (streak plate)

17. What is the Luster of a mineral? • Luster – used to describe how a mineralreflectslightfrom itssurface • Minerals containing metals are oftenshiny • Earthy, waxy, and pearly

18. What does Density have to do with Minerals? • Each mineral has a characteristicDensity • Density – or mass per unit volume; Density = mass/volume • Displacement – the volume of the displaced water equals the volume of the the sample

19. What Kind of Shape does a Mineral have? • Minerals have a crystal structure • Cubic • Hexagonal • Tetragonal • Orthorhombic • Monoclinic • Triclinic

20. What is Mineral Cleavage? • Cleavage – A mineral’s ability to split easily along a flat surface • The ability to break apart depends on the arrangement of the atoms in the mineral Cubic Cleavage Basal Cleavage

21. What is Mineral Fracture? • Fracture – How a mineral looks when it breaks apart in an irregular way

22. What Special Properties does a Mineral have? • Fluorescence –minerals that glow under ultraviolet light • Magnetism - ex. Loadstone • Chemical Reactivity- ex. Calcite gives off carbondioxide • Electrical Properties – ex. quartz

23. How are Minerals Formed? • Two General Ways: • Crystallization of melted materials • Minerals fromMagma • Crystallization of materials dissolved in water • Minerals fromHot watersolutions • Minerals formedby evaporation

24. What is Crystallization? • Crystallization • the process by which atoms are arranged to form a material with a crystal structure

25. How do Minerals form from Magma? • Minerals form as magma cools inside the crust, or as lava hardens on the surface

26. What Effects Crystal Size? • Rate at which magma cools • Slower cooling forms larger crystals • The amount of gas the magma contains • The chemical composition of the magma

27. How do Minerals Form from Hot Water Solutions? • Magma beneath Earth’s surface has heated the water to a high temperature beneath Earth’s surface causing minerals to dissolve • When this solution cools the elements and compounds leave the solution and crystallize as minerals

28. How are Minerals Formed by Evaporation? • As water turns to vapor it leaves behind the mineral • Example: A salt water solution leaves behind large crystals of salt

29. Where are Minerals Found? • Earth’s crust is made up of a variety of minerals however; rare and less common minerals are usually located near plateboundaries because of volcanic activity and mountain building

30. How are Minerals Used? • Minerals are the source of • Metals ex. Aluminum, Iron • Gemstones ex. Rubies and Sapphires • Other Useful materials ex. Talc (talcum powder)

31. Ore What? • Ore - A rock that contains a metal or economically useful mineral • Most metals, gemstones, and useful minerals must be separated from their ores