Minerals and Their Properties: What is a Mineral?

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

NOT A MINERAL? • 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 http://www.mineralogy4kids.org/groups.html

What Are Properties of Minerals???

1. 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 anypiece 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”)

Minerals and Their Properties: What is a Mineral?