Mineral ID

1. Mineral ID How to identify a mineral by its properties Baker 7th grade science

2. Today you will learn • Which mineral properties are most important in identification. • How mineral are identified by their properties. Baker 7th grade science

3. A mineral’s appearance helps identify it. • In order to identify a mineral, you need to observe it properties – characteristics that help identify it. • There are 5 main properties that we use to identify. There are many minor properties that can also help id a mineral. Baker 7th grade science

4. Mineral Property #1 Color & Streak • Color is the first thing someone notices when they view a mineral. • Color is also one of the big reasons that attract people to minerals. • Generally speaking, color is not a good property to be used in the identification of minerals. It is usually the first property to confuse a novice collector into making an incorrect identification. • Many minerals have different colors and some minerals' colors are identical to other minerals' colors. Baker 7th grade science

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6. Mineral Property #1 Color & Streak • Streak is closely related to color, but is a different property because the color of the mineral may be different than the color of the streak. • Streak is actually the color of the powder of a mineral. It is called streak because the proper way to test for streak is to rub a mineral across a tile of white unglazed porcelain and to examine the color of the "streak" left behind. Baker 7th grade science

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8. Mineral Property #1 Color & Streak • Pyrite (known as "Fool's Gold") is always brassy yellow when found in crystals, even broken crystals, of any size; but when powdered, produces a black streak. • Gold's streak, by the way, is yellow! • Hematite's streak is blood-red • Galena's streak is lead gray Baker 7th grade science

9. Mineral Property # 2Luster • A mineral’s luster is the way in which light reflects from the surface. • The two major types of luster are metallic & nonmetallic. Baker 7th grade science

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11. Mineral Property # 2Luster • Some other ways to describe luster are • Dull - just a non-reflective surface of any kind • Earthy - the look of dirt or dried mud • Fibrous - the look of fibers • Greasy - the look of grease • Gumdrop - the look a sucked on hard candy • Metallic - the look of metals • Pearly - the look of a pearl • Pitchy - the look of tar • Resinous - the look of resins such as dried glue or chewing gum • Silky - the look of silk, similar to fibrous but more compact • Submetallic - a poor metallic luster, opaque but reflecting little light • Vitreous - the most common luster, it simply means the look of glass • Waxy - the look of wax Baker 7th grade science

12. Quick Check • Get out your whiteboard and quickly answer the following: • What is the first thing someone notices about a mineral? • What do we call the color of the powdered mineral? • Which is more reliable: streak or color? Baker 7th grade science

13. Mineral Property # 3How a mineral breaks • When a mineral breaks it does so either by fracturing or by cleaving. • Cleavage is the tendency of a mineral to break along flat surfaces. • Crystal cleavage is a smooth break producing what appears to be a flat crystal face. • Fracture is the tendency of a mineral to break into irregular pieces. Baker 7th grade science

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15. Mineral Property # 3How a mineral breaks • When a mineral breaks it does so either by fracturing or by cleaving. • Cleavage is the tendency of a mineral to break along flat surfaces. • Crystal cleavage is a smooth break producing what appears to be a flat crystal face. • Fracture is the tendency of a mineral to break into irregular pieces. Baker 7th grade science

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17. Mineral Property #4Hardness • A mineral’s hardness is its resistance to being scratched. • A scale known as the Moh’s scale is often use Baker 7th grade science

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19. Mohs Scale Baker 7th grade science

20. Mineral Property #5Density • Each mineral has a specific density. • Density is the mass of a given space or in scientific terms the mass per unit of volume. • For example, if you have two minerals of the same size one might be heavier than the other. The galena will be three times heavier than the same size of quartz. Baker 7th grade science

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22. Mineral Property #5Density • Geologists measure density by the following: • First they use a balance to determine the mass of a sample. • Second, they place the mineral in water to see how much water it displaces. • The volume of displace water = the volume of the sample • Third they use the following formula: Density = Mass/Volume Baker 7th grade science

23. Brain Check • Get out your whiteboard and quickly answer the following: • If you break a mineral and it breaks into cubes, is it fracture or cleavage? Why? • If you break a mineral with a hammer and it falls apart into a million different pieces, is it fracture or cleavage? Why? • Name three things you can scratch talc with. • What is the formula for density? Baker 7th grade science

24. Some minerals have specific properties • Fluorescence: some minerals glow when exposed to ultraviolet light • Magnetic: Some minerals are attracted to magnets • Acid: Some minerals react with acid by bubbling Baker 7th grade science

25. SLCDFHSome Llamas Climb Down Funny Hills • Streak • Powdered Color • Luster • How shiny • Cleavage • Breaks in sheets or blocks • Density • How much mass in a given volume • Fracture • Just crumbles & breaks • Hardness • Can be scratched by Baker 7th grade science