MINERALS. How we use minerals every day. DO NOW 11/4. 1. What is a mineral? Make a list of things that describe minerals. Bonus: What is your birthstone? Is it a mineral?. PEARLS AND OPALS ARE NOT MINERALS!! Why not?. Birthstones.
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DO NOW 11/4 1. What is a mineral? Make a list of things that describe minerals. Bonus: What is your birthstone? Is it a mineral?
PEARLS AND OPALS ARE NOT MINERALS!! Why not? Birthstones Pearls are biologically formed and opals do not have a crystal structure.
Predict! • What will happen when the common minerals are ignited? NaCl: sodium cholride solution- table salt KCl: potassium chloride solution- “saltless” salt substitute
A mineral is: • Naturally occurring • Inorganic • Solid • Has a definite chemical composition • Has crystalline structure All physical properties of minerals come from the “internal arrangement of atoms”
Internal Structure of Minerals • How atoms are bonded together and arranged Ex. Quartz Silicon-oxygen tetrahedron
A little about Quartz: • One of the most abundant minerals in the world (Quartz and feldspar fight for #1) • Makes beach sand • Makes glass (melted beach sand) • Chemical formula: SiO2 • Since it is SiO2, there is twice as much oxygen as silicon. • According to the Reference Tables pg 11, Oxygen is the #1 element in the crust with Silicon #2 (and about half that of Oxygen) • Crystal shape is a pyramid called a “tetrahedron” • Tetra = 4 • hedron =“sided solid
How they form: • Supersaturated solution- water evaporates and molecules collect and precipitate minerals in cavities (geodes) • Cooling and solidification of magma (and lava) find minerals embedded in rocks • Heat and pressure to existing minerals
Mineral Identification Tests • The Color Test- easiest test to do but not always reliable • The Streak Test -The color of the powdered mineral. -Performed by rubbing the unknown mineral on an unglazed tile.
Hardness- a mineral’s resistance to scratching. • This should not be confused with brittleness. A diamond is very hard and will scratch a hammer but a hammer will smash a diamond. Likewise, talc, one of the softest minerals, is not squishy. It will still put a serious hurting on you if you get hit in the head with it. • Moh’s Scale of Hardness • Talc (Softest) • Gypsum • Calcite • Fluorite • Apatite • Feldspar (AKA Albite) • Quartz • Topaz • Corundum • Diamond (Hardest)
Key Points of a Hardness Test • Choose one mineral to be the scratcher and one to be the scratchee. • Pick a smooth, flat surface to scratch. • After doing the test, wipe the powder away to confirm that the scratchee really got scratched. • If the scratchee did not get scratched, switch the two rocks and repeat. Hardness Tools • Fingernail 2.5 • Penny 3.5 • Iron Nail 4.5 • Glass Plate 5.5 • Steel File 6.5 • Streak Plate 7
The Luster Test • Luster: the way a mineral shines or doesn't shine when reflecting light (metallic vs. nonmetallic) Types of Luster • Metallic- looks like shiny metal • Non-metallic- all the other ways that a mineral can shine • Glassy/vitreous- shines like a piece of broken glass (most common non-metallic) • Dull/earthy- no shine at all • Resinous/waxy- looks like a piece of plastic or dried glue • Pearly- looks oily it may have a slight rainbow like an oil slick on water. Also looks like the inside of some clam shells • Adamantine- brilliant, sparkling shine like a diamond
Cleavage -To break along flat surfaces. • Examples of Cleavage • Cubic- To break into cubes (halite)
Fracture -The way a mineral without cleavage breaks (rough edges). • Examples of Fracture: • conchoidal- to break in a scooped out bowl shape- like a conch (sea snail) • hackly fracture- to have irregular sharp edges • splintery- to break into long, thin needles
Specific Gravity • The density of a mineral compared to the density of water. • Ex. Pyrite’s density = 5g/cm3 Specific Gravity= pyrite’s density density of water
Miscellaneous Tests • Acid- Calcite and powdered dolomite will effervesce (fizz) in dilute hydrochloric acid (HCl) • Smell- Sphalerite will give off a rotten-egg smell when streaked on a streak plate. (Note: pure sulfur does not smell like rotten eggs!) • Magnetism- Magnetite (AKA Lodestone) will pick up paper clips (weak samples will only be able to pick up staples)
Tests Continued • Taste- Halite is rock salt and will taste salty. *Do not taste the samples since some have been tested with acid to see if it is calcite. • Fluorescence- some minerals (mostly forms of calcite) will glow in fluorescent colors under a black (UV) light. • Double refraction- some clear forms of calcite (Iceland Spar) will make a double image of words.
DO NOW 11/5 • Using your ESRT, identify the mineral with the following properties: Non metallic luster Hardness of 5.5 Cleavage (56 and 124° angles) Black to dark green in color Amphibole (commonly known as hornblende)
DO NOW 11/6 • Pick up a worksheet at the back table. • Ignore the word Quiz 2- this is practice as your DO NOW. Use your ESRT to complete the front of the worksheet.
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Ore • Mineral that contains a high percentage of a commercially valuable substance. • Examples note mostly have a metallic luster • PbS Galena • Fe3 O4 Magnetite
Using Page16 • Organization: