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Topic: Mineral ID L .O. Students will explain how to identify a mineral by its properties by using graphic organizer STANDARD: S3 - CONCEPT OF EARTH AND SPACE Baker 7th grade science What is a mineral? Naturally occurring Non-organic Characteristic chemical composition Distinctive physical properties Crystalline structure Do Now Name some properties of mineral Mineral identification http://www.brainpop.com/science/earthsys tem/mineralidentification/preview.weml Mineral Property #1 Color & Streak . Color is the first thing someone notices when they view a mineral. It is not a reliable property . It does not help in identifying minerals properly. Many minerals have different colors and some minerals' colors are identical to other minerals' colors. Color & Streak Color: Not Mineral Specific Mineral Property #1 Color & Streak: Streak is the powdered form of a mineral when it is rubbed on a porcelain plate. the color of the mineral may be different than the color of the streak. Mineral’s Identification 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 Mineral Property # 2 Luster A mineral’s luster is the way in which light reflects from the surface. The two major types of luster are metallic & nonmetallic. Luster: How minerals reflect light Metallic Nonmetallic Mineral Property # 2 Luster 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 Silky - the look of silk, similar to fibrous but more compact Waxy - the look of wax Quick Check 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?Explain Why? Mineral Property # 3 How a mineral breaks Cleavage: planes of weakness along which minerals can break Fracture: surfaces along which minerals can break Mineral Property #4 Hardness 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 Hardness: Based on Moh’s scale of hardness Mineral Property #5 Density (Specific gravity) Each mineral has a specific density. Density is the mass of a given space or in scientific terms the mass per unit of a certain 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. Mineral Property #5 Density 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 Some minerals have specific properties (Other) Fluorescence: some minerals glow when exposed to ultraviolet light Magnetic: Some minerals are attracted to magnets Acid: Some minerals react with acid by bubbling Brain Check 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? SLCDFH Some Llamas Climb Down Funny Hills Streak Luster How much mass in a given volume Fracture Breaks in sheets or blocks Density How shiny Cleavage Powdered Color Just crumbles & breaks Hardness Can be scratched by Home Work Write one page about your Birthstone .It must have: -What is your birthstone (including its picture)? -How is it formed? -Which part of the world is it found mostly? -What are its basic properties and characteristics? -What your birthstone represents?