MINERALS AND THEIR PROPERTIES

WHAT IS A MINERAL? A MINERAL IS A: SOLID NATURALLY OCCURING (made up of elements) INORGANIC CRYSTAL SHAPE (unique to the mineral) CHEMICAL COMPOSITION (elements bond together to make a compound)

WHAT DOES THAT MEAN? Naturally Occurring = NOT man-made Inorganic = NOT made of/from a living thing Crystal Shape = Repeating pattern of atoms Chemical Composition = chemical formula Ex: Quartz has a chemical formula of SiO2

NOT A MINERAL? COAL IS NOT A MINERAL, WHY? It is not inorganic because it formed from the remains of living organisms It does not have a crystal shape

NOT A MINERAL? Pearls are organic because they are made from oysters. PEARL IS ALSO NOT A MINERAL, WHY? Pearls are organic because they are made from oysters. They do not have a crystal shape

NOT A MINERAL? Glass does not a crystal shape. GLASS IS ALSO NOT A MINERAL, WHY? Glass does not a crystal shape.

NOT A MINERAL? 1: It is man-made (not naturally occurring) STEEL IS ALSO NOT A MINERAL, WHY? 1: It is man-made (not naturally occurring) 2: It does not have a chemical composition because it is a mixture of iron and carbon 3: It does not have a crystal shape

“Diamonds are Forever” Reading Before you Read: Review the definition of a mineral (SNICC) After you Read: Answer these questions: Can the LifeGem diamonds be considered true minerals? Explain your answer. How are these diamonds different than diamonds mined out of the ground? Would you want to use this company for yourself or for a relative?

TWO GROUPS OF MINERALS Nonsilicate Minerals Silicate Minerals Have both Silicon (Si) and Oxygen (O) elements in them Make up more than 90% of Earth’s crust Might have other elements in them as well Examples: Quartz (SiO2) Talc Mg3Si4O10(OH)2 Do NOT contain Silicon and Oxygen Dividing into different classes depending on elements in them Examples: Copper (Cu) Calcite (CaCO3) Galena (PbS) http://www.mineralogy4kids.org/groups.html

What Are Properties of Minerals???

1. COLOR Impurities Many minerals have same color Not reliable due to: Impurities Many minerals have same color Some minerals have more than one color

COLORS OF FLUORITE                                                           

2. HARDNESS The ability of a mineral to resist being scratched. Relative to the hardness of other minerals and objects 2 scales Field hardness scale Moh’s hardness scale

HARDNESS FIELD HARDNESS SCALE Fingernail Copper Penny Steel Nail Glass Plate Steel File                          

MOH’S HARDNESS SCALE Talc Gypsum Calcite Fluorite Apatite Feldspar Quartz Topaz Corundum Diamond

3. LUSTER The way a mineral reflects light Either Metallic or Nonmetallic Never described as “shiny” (that is what luster means)

METALLIC LUSTERS Shines like a metal: Chrome, Silver, Copper, Gold, Bronze, Lead, etc.

NONMETALLIC LUSTERS Brilliant (High Shine/Sparkly) Pearly or Silky Glassy(Vitreous) Waxy/Greasy Dull Earthy

4. STREAK Powdered residue left behind when rubbed across a porcelain tile Only works for minerals with a hardness less than 7 (tile=7) Streak may be different than outer color More consistent/reliable than color

5. CLEAVAGE The breaking of a mineral along flat surfaces Can be 1,2, or 3 directional 3 Directions: Similar to sides of a cube or rhombus Mica breaks into single sheets- 1 Directional

6. FRACTURE Breaking of a mineral in an uneven or jagged fashion “Splintery”-splits like wood “Earthy”/Uneven “Conchoidal”-curved “Fibrous”- like fibers

7. DENSITY = Mass per volume (g/mL) Every mineral has its own unique density, regardless of its size Ex: The density of any piece of gold will always be 19 g/mL The density of any piece of silver will always be 10.5 g/mL

8. CRYSTAL SHAPE Microscopic shape of crystals Slow cooling = larger crystals Fast cooling = smaller crystals Cubic, Hexagonal, Octagonal, Rhomboid, Trapezoidal, etc

9. SPECIAL PROPERTIES Magnetism (lodestone/magnetite) Taste (Halite-salty) Acid reaction (calcite) Double refraction Fluorescence (glow in UV) Phosphorescence (glow continues) Odor (Sulfur) Radioactivity (Uraninite)

ScienceNow Diamond Factory Diamond Factory Video (click on “Watch Diamond Factory”)