Chapter 2 Minerals Remember >>>> The Earth is made of matter anything that has mass & takes up space Matter- anything that has mass & takes up space Most solid matter on Earth is either: a mineral a mineral a rock (but a rock is just a mixture of minerals)a rock (but a rock is just a mixture of minerals)

What is a Mineral ? - Natural (not man-made) - Inorganic (never living) - Solid - Has an orderly structure of atoms - Has a definite chemical composition

Minerals:

Locating and Mining Minerals Minerals can be found in: Rocks Sand Soil Seashells Below Earth’s surface

Minerals are dug or mined out of the earth People mine for minerals on every continent except for Antarctica

Minerals can be strip-mined or dug far below the earth’s surface Often minerals need to be separated from rock. Geologists can melt the minerals or use chemicals to break apart the rock

So how do we identify minerals?

How do I identify different minerals ? COLOR Color is not always good to use All of these are quartz

Use 7 other properties to identify minerals: 1.Streak = color of mineral in powdered form - rub mineral across a streak plate to see the color

7 Mineral Properties Cont… 2. Luster = how light reflects off surface of mineral A. Metallic = looks like shiny metal B. Vitreous (glassy) = shines like glass C. Dull D. Waxy

7 Mineral Properties Cont… 3. Crystal Form = outward shape of mineral - as mineral grows in size it will always keep the same crystal form A. Cubic B. Sheet-Like C. Rhombohedral D. Massive = no crystal form

7 Mineral Properties Cont… 4. Hardness = resistance of mineral to being scratched - rub 2 minerals together, the harder mineral will scratch the softer mineral - use the Moh’s Hardness Scale to find hardness range for minerals: 1 - TalcSOFTEST fingernail Gypsum 3 - Calcite steel nail Fluorite manufactured glass Apatite 6 - Orthoclase 7 - Quartz 8 - Topaz 9 - Corundum 10 - Diamond HARDEST

7 Mineral Properties Cont… 5. Cleavage = tendency of a mineral to break along smooth, even surfaces (always in the same direction/directions) A. 1 Direction = always breaks into sheets EX: Muscovite & Biotite B. 2 90° = mineral always breaks into squares EX: Galena C. 3 90° = mineral always breaks into cubes EX: Halite  Some minerals do not display cleavage, this property is called Fracture EX: Quartz

7 Mineral Properties Cont… 6. Density (Specific Gravity) = how heavy a mineral feels EX: Galena is very heavy for its size EX: Talc is very light for its size

7.Other Properties A. Smell = some mineral have a distinct smell EX: Sulfur smells like rotten eggs B. Feel = some minerals feel greasy EX: Graphite C. Magnetic = some minerals behave as magnets EX: Magnetite D. Taste = salty taste of Halite CAUTION: DO NOT TASTE ANY MINERAL E. Reacts to Acid = some minerals fix when a weak acid (HCL) is dropped on them EX: Calcite

Do I use minerals ?  YES 1. Salt (halite) 2.pencil lead (graphite) 3.make-up (talc) 4.window glass (quartz)

How do minerals form? 4 Main Ways: 1. Crystals form out of magma 2. Precipitate (solid forms) out of water 3. Change in pressure and temperature 4. From hot water = (causes chemical reactions to form new minerals)

6 Major Mineral Groups: 1.Silicates = minerals that contain elements silica, oxygen and other minor elements EX: Quartz, Olivine, Muscovite, Biotite, Feldspar - form from cooled magma

2. Carbonates = minerals that contain oxygen, carbon, and other minor elements EX: Calcite - form in shallow oceans

3. Oxides = minerals that contain mainly oxygen and minor elements EX: Hematite - form in variety of environments

4. Sulfates & Sulfides = minerals that contain sulfur and other minor elements EX: Gypsum, Galena, Pyrite - forms in hot water solutions

5. Halides = minerals that contain fluorine, chlorine, and other minor elements EX: Halite - forms from evaporation/precipitation

6 Major Mineral Groups: 6. Native Elements = pure single forms of minerals EX: Gold, Silver, Copper, Sulfur, Diamond, Graphite - forms in hot water solutions

What is a gemstone? Any mineral that can be cut, polished, and sold for a profitAny mineral that can be cut, polished, and sold for a profitEX: -Diamond -Ruby (mineral Corundum) = Red -Emerald (mineral Beryl) = Green -Amethyst (mineral Quartz) = Purple -Sapphire (mineral corundum with impurities of titanium) = Blue