Minerals Patterns in Nature

1. MineralsPatterns in Nature CMU Bill Palmer Lecture 4 Central Methodist University

2. What are Minerals? • Natural • Chemically Pure • Make up “rocks” • Solid • Inorganic • Often form crystals • Crystal structure is organized arrangement of atoms

3. How Rocks and Minerals Different? Minerals are chemically pure Rocks are composed of minerals Big important hint: Learn the Minerals and the Rocks will be easy to learn!!

4. Your Very Life Depends on Minerals

5. General Facts about Minerals • Between 2 - 3,000 have been identified • A few are “native elements” -- made of only one element, such as sulfur, gold. copper, and graphite (carbon) • Most are compounds, especially the silicate group (Si, O) • Other important groups are oxides, carbonates, and sulfides

6. About a dozen are common in most rocks • Quartz • Feldspar (group) • Muscovite (white mica) • Biotite (black mica) • Calcite • Pyroxene • Olivine • Amphibole (group) • Magnetite, limonite, and other iron oxides • Pyrite • Galena • Barite

7. Common Uses Include: • Aluminum--packaging, transport, building • Beryllium--gemstones, fluorescent lights • Copper--electric cables, wires, switches • Feldspar--glass and ceramics • Iron--buildings, automobiles, magnets • Calcite--toothpaste, construction

8. Minerals are identified by their key characteristics • Hardness • Crystal shape (form) • Luster • Color • Streak • Cleavage/fracture • Density (specific gravity) • Special properties --reaction to acid --fluorescence --salty taste --magnetism Learn how to test minerals for these characteristics instead of trying to memorize each mineral!! With 3,000 different minerals it would be next to impossible to learn all the names!!

9. Mineral Hardness • Ability to scratch another mineral • Mohs scale from 1 (talc) to 10 (diamond) • Quartz (most common mineral and most dust particles) is 7

10. Mineral Hardness Hardness of some common items: Moh’s Scale • 2.5 Fingernail • 2.5–3 Gold, Silver • 3 Copper Penny • 4-4.5 Platinum • 4-5 Iron • 5.5 Knife Blade • 6-7 Glass • 6.5 Iron Pyrite • 7+ Hardened Steel File • 1 Talc Talcum powder. • 2 Gypsum Plaster of Paris. Gypsum is formed when seawater evaporates from the Earth’s surface. • 3 Calcite Limestone and most shells contain calcite. • 4 Fluorite Fluorine in fluorite prevents tooth decay. • 5 Apatite When you are hungry you have a big "appetite". • 6 Orthoclase Feldspar In German, "feld" means "field". • 7 Quartz Found everywhere. • 8 Topaz The November birthstone. Emerald and aquamarine are varieties of beryl with a hardness of 8. • 9 Corundum Sapphire and ruby are varieties of corundum. Twice as hard as topaz. • 10 Diamond Used in jewelry and cutting tools. Four times as hard as corundum.

11. Crystal Shape (Form) • External structure due to internal arrangement of the atoms • Six basic groups of shapes, with about three dozen variations

12. Luster • Describes how light reflects off the surface • Main categories are “metallic” and “non-metallic” • Non-metallic • dull • glassy • waxy • pearly

13. Color • Results from ability to absorb some wavelengths and reflect others • Some minerals have characteristics colors • Others vary due to chemical differences or impurities (atoms mixed inside the main elements) COLOR is usually the worst way to identify a mineral.

14. Streak • Color of the powder when rubbed on a “streak plate” (unglazed porcelain) • May be same as hand-specimen or different • Some paint is based on powdered minerals (streaks)

15. Mineral cleavage/fracture • Some minerals split along flat surfaces when struck hard--this is called mineral cleavage • Other minerals break unevenly along rough or curved surfaces--this is called fracture • A few minerals have both cleavage and fracture • Due to how the atoms are arranged Be sure you understand the difference between CLEAVAGE and FRACTURE.

16. Density (Specific Gravity) • All minerals have density (mass / volume), but some are very dense • Examples include galena, magnetite, and gold • Specific Gravity is the density of the mineral compared with density of water • Remember our Lab? • Some minerals just feel “heavy”

17. Carbonates react with dilute HCl and other acids by fizzing or bubbling (releasing CO2 gas) Special Characteristics--the “Acid Test”

18. Special Characteristics-- Fluorescence • Some minerals will glow when placed under short-wave or long-wave ultraviolet rays • Franklin and Ogdensburg NJ are famous for their fluorescent minerals

19. Special Characteristics--Salty Taste • DO NOT TASTE MOST MINERALS! • Halite is the exception--it will taste salty • Kaolinite (clay) will stick to your tongue

20. Special Characteristics--Magnetism • Many iron minerals will produce an invisible magnetic force field • “Lodestone” was used by Vikings more than 1,000 years ago as compasses Magnetite

21. A detailed look at some common minerals Or Some common minerals that make-up most rocks and some minerals your kids may ask you what they are and you will want to know so you can impress them.

22. Quartz • Very hard 7.0 • Many, Many forms • Clear • Rosy=pink • Milky=white • Smoky=black • Chalcedony=multicolor • Agate=color rings • Chert=white, brown, tan (very common) • Mozarkite=pink/purple bands (MO State Rock) • Amethyst=purple • Jasper=dark blood red

23. QuartzWhich is which?

24. QuartzWhich is which? Amethyst Rosy Quartz Milky Chalcedony Smoky Agate Mozarkite Chert Clear Jasper

25. Feldspar • Hard 6.0 • Vitreous, pearly • Good Cleavage, breaks at 900 • Plagioclase • Sodium Calcium Aluminum silicate • White, Yellow, Pink • Striations • Orthoclase • Potassium Aluminum Silicate • White, yellow, pink • NO Striations

26. How to Identify Feldspars Check the Color dark ORTHOCLASE FELDSPAR pink light PLAGIOCLASE FELDSPAR Check for Striations yes no

27. Mica • Soft 2.5-3.0 • “Saran Wrap” • Breaks in thin layers • Biotite • Dark • Muscovite • Clear

28. Calcite • Soft 3.0 • Excellent cleavage in 3 directions NOT 900 • Colorless • White • Yellowish • Rhombohedrons

29. Pyroxene • Hard 5.5-6.0 • “Augite” • Dark Green to Gray • Eight-sided prisms

30. Olivine • Hard 7.0 • White Streak • Pale to dark olive Green • Peridot is the Gemstone

31. Amphibole • Hard 5.5 • White to gray Streak • Dark gray to black

32. MagnetiteHematite, Limonite • Iron Oxides • Iron Ores • Color Varies with amount of Iron • Limonite = yellow • Hematite = reddish • Magnetite = black • Tell apart by streak

33. Pyrite • Hard 6.0-6.5 • Dark gray Streak • Brassy yellow • “Fool’s Gold”

34. Galena • Soft 2.5 • Silver Gray • Metallic • Perfect Cubes • MO State Mineral • Source of Lead

35. Barite • Soft 3.0-3.5 • White, but can be stained reddish with iron • Heavy • “Tiff” of S MO

36. Wrap-ups • 1. Research the common uses for the 12 common minerals in the lecture. • 2. List the diagnostic characteristics of minerals and include some of the possible variations. • 3. What is the difference between a rock and a mineral? • 4. Define a mineral. • 5. What Moh’s Scale and what are some hardness of some common objects.

37. Wrap-ups • 6. What is a crystal? Do all minerals form crystals? What causes a crystal? • 7. What is luster? What are the main types? • 8. Distinguish between cleavage and fracture. • 9. Why is color a poor distinguishing characteristic when identifying minerals? • 10. What is the Missouri State Mineral?

38. Useful Web Sites • www.mii.org • www.mineral.galleries.com/minerals • www.mineral.net • www.usgs.gov