1. Minerals
Ms. Rudisill

2. What is a mineral? 1. Made up of elements in the earth’s crust!
2. Minerals must have the following 5 characteristics:
Occurs naturally
Solid
Definite chemical composition
Atoms are arranged in an orderly pattern – crystal
Inorganic

3. 3) 8 elements make up 98.5 % of the earth’s crust
Oxygen and Silicon are the most abundant
90% of ALL minerals are made with Oxygen and Silicon
4) Most Minerals are compounds
Halite – NaCl
Quartz – SiO2
5) A few minerals are single elements, native elements
Silver – Ag
Diamond - C

4. How Do minerals form? 1. Magma – molten rock
a) Atoms in magma solidify
b) Magma starts to cool
c) Atoms move close together and form compounds
d)Types of minerals that form depend on the type and amount of elements in the magma
e) Cooling time determines size of minerals
Long cooling time = large minerals
Short cooling time = small minerals

5. 3) Pressure A rock is put under great temperature and pressure
Minerals begin to break down chemically
Pressure becomes great enough to change the minerals without melting them.
Atoms recombine forming new minerals
Minerals grow in opposite direction from the pressure.

6. 4)Water
a) Evaporating saltwater
-bodies of saltwater evaporate
-As saltwater evaporates the minerals crystallize
-Ex: Gypsum and Halite
b) Surface and groundwater
-Surface and groundwater carry dissolved materials into lakes or seas
-Dissolved minerals settle on the bottom of the lake or sea
-Ex: Mica

7. c) Hot-water Solutions -Groundwater makes its way through the ground in Earth’s surface -Magma inside Earth mixes with the water -Water evaporates and causes the dissolved metals and other elements to precipitate out of the water -ex: gold, copper, sulfur, pyrite, and galena

8. Mineral resources Source of metals - Ores Gemstones/Jewelry Abrasives
Fertilizer
Glass

9. Identifying minerals observable properties
Color
Luster – the way a mineral shines in light
Crystal Structure
Crystal size is determined by the amount of time it has had to cool.
Long cooling time creates large mineral crystals
Short cooling time creates small mineral crystals

10. Property of Color Some minerals have distinct colors
Many minerals have similar colors
Some minerals have many colors
Some minerals change colors

11. Identifying minerals testable properties
Streak
Color of a minerals powder
Obtain streak by rubbing the mineral on an unglazed white tile (streak plate).
Color of the mineral may vary, but the streak is always the same
Streak Rules
Streak of a metallic mineral is at least as dark as the mineral
Streak of a nonmetallic mineral is usually colorless or white

12. Property of luster Metallic – shines like polished metal
Nonmetallic – may be shiny but not like a metal
Vitreous – like glass; Quartz
Pearly - Mica
Adamantine- hard brilliant luster; Diamond
Greasy
Oily
Dull
Earthy

13. Crystal structures
Crystal is an orderly arrangement of atoms in a mineral
All minerals have a crystal structure, but you cannot always see the structure.
Six Crystal Systems
Cubic
Orthorhombic
Tetragonal
Hexagonal
Monoclinic
Triclinic

14. Crystal structures

15. Identifying minerals testable properties
Cleavage
Tendency of a mineral to split easily along flat surfaces.
Useful because cleavage surfaces can be observed even on tiny mineral grains.
Fracture
When minerals break in directions other than along cleavage surfaces.
Conchoidal Fracture – surface is smooth and curved like the inside of a clam shell
Splintery Fracture – Jagged surface with sharp edges
Irregular Fracture – leaves generally rough surfaces

16. Identifying minerals testable properties
Hardness
Resistance to being scratched
Use the Mohs Scale of Hardness
Scale was created by Friedrich Moh
Scale goes from 1 (softest mineral) to 10 (hardest mineral)
Determining Hardness
If a mineral can be scratched by an object than it is softer than that object.
If a mineral is not scratched by an object than it is harder than that object

17. Identifying minerals testable properties

18. Mohs’ Scale of Hardness
Mineral
Simple Test
Talc
Fingernail scratches it easily
Gypsum
Fingernail scratches it
Calcite
Copper Penny scratches it
Fluorite
Steel knife scratches it easily
Apatite
Steel knife scratches it
Feldspar
Steel knife does not scratch it, it scratches window glass easily
Quartz
Hardest common mineral; it scratches steel and hard glass easily
Topaz
Harder than any common mineral
Corundum
It scratches Topaz
Diamond
Hardest of all minerals

19. Identifying minerals testable properties
Fluorescence – minerals that glow under ultraviolet light.
Magnetism – magnetic
Acid Test – mineral reacts when in contact with Hydrochloric (HCl) acid.
Specific Gravity
Ratio of its mass to the mass of an equal volume of water.
Tells you how many times denser the mineral is than water.

20. Identifying minerals testable properties
Double Refraction
Iceland Spar Calcite
Causes single object to appear as two objects when viewed through the calcite
Taste – Example Halite has a salty taste

21. Possible Other Properties
Salty Taste
Double Refraction
Magnetic
Heavy
Greasy (smudges on fingers and paper)
Flakes apart
6-sided crystal (you might have two of these!)
Almost perfect square/rectangle pieces
Feels soft like powder!

22. Mineral Groups
Minerals are divided into two groups based on the elements they are composed of.
Silicate Minerals
Minerals that contain a combination of silicon and oxygen
Silicate minerals can still contain other minerals, but are made up mostly of Silicon and Oxygen.
Nonsilicate Minerals
Minerals that do not contain a combination of the elements Silicon and Oxygen
These minerals may have one of these minerals