1. To be able to identify these and other minerals, we need to look at the properties used to separate and distinguish these minerals.

2. Rarely is a mineral identified by a single property.
Identifying Minerals
Remember!:
Rarely is a mineral identified by a single property.
These properties need to be considered together to correctly identify a mineral.

3. color
Color is the most easily observed mineral property and the least useful!

4. color
Some exceptions to the color rule would be cinnabar, which is always red, and malachite, which is green.

5. Many minerals have a similar color.

6. color
Many minerals can turn colors due to impurities, or they can change colors in various circumstances.

7. color
For example, pure quartz is colorless or white, impurities can make the mineral rose, purple or pink!

8. Quiz
Break!

9. How many of the characteristics of minerals can you name?
Discuss the following!
How many of the characteristics of minerals can you name?
Why isn’t color a very good property to identify most minerals?

10. Luster refers to the way a mineral shines in reflected light.
Notice the difference between these two minerals?

11. luster
The mineral on the left has a metallic luster, the one on the right, a nonmetallic luster.

12. luster
There are several terms used to describe nonmetallic luster. Examples could be vitreous, like the quartz on the left, or pearly, like the gypsum on the right.

13. Other terms that might be used include greasy, dull, and earthy.
Can you tell which of these has an earthy luster and which has a vitreous luster?
Were you
Right?
Vitreous
Earthy

14. streak
Streak of a mineral is the color of its powder when rubbed on an unglazed white tile.

15. The streak is often not the same color as the mineral.
A minerals color may vary, but the streak rarely will!

16. crystal shapes
Crystal shape can be a useful property to identify minerals if the minerals have had the time and space to form crystals. Most mineral grains that are found in rocks, lack the room to grow.

17. Crystal Shape (or form)
External expression of a mineral’s internal atomic structure
Planar surfaces called crystal faces
Angles between crystal faces are constant for any particular mineral
Quartz
Pyrite

18. cleavage
The cleavage of a mineral is its tendency to split easily or to separate along flat surfaces.
Cleavage can even be observed on tiny mineral grains making it a very useful property!
Do NOT confuse cleavage planes with crystal faces! Crystal faces are just on the surface and may not repeat when the mineral is broken!

19. cleavage
Mica is probably the best example as it splits into thin sheets. It is said to have one perfect cleavage.

20. Cleavage (1 direction):
Example: mica

21. cleavage
Feldspar splits readily in two directions, always at or near right angles.

22. Cleavage (2 directions):
orthoclase
amphibole

23. Calcite and galena cleave in three directions.
cleavage
Calcite and galena cleave in three directions.
They are said to have three good cleavages.

24. Cleavage (3 directions):
halite
calcite

25. Cleavage (4 directions):
fluorite

26. Not all minerals show cleavage.
Those that don’t break along cleavage surfaces are said to have fracture.

27. Minerals that have some weak bonds will show cleavage
Fracture
Minerals that have some weak bonds will show cleavage
Minerals,like quartz, that have very strong bonds show fracture

28. Quiz
Break!

29. There are four common minerals, how many can you name?
Discuss the following!
There are four common minerals, how many can you name?
Of the four common minerals, which one makes up over 60% of the Earth’s crust?

30. The hardness of a mineral is its resistance to being scratched.
Diamond is the hardest of all minerals, and talc is the softest.

31. Friedrich Mohs devised a hardness scale.
In this scale, ten wellknown minerals are given numbers from one to ten.
Lets take a look at the ten minerals used and some of the simple tests.

32. Hardness
Talc (left) is the softest and has a hardness of 1. A soft pencil lead will scratch talc.
Gypsum is a bit harder and has a hardness of 2. A fingernail scratches gypsum.

33. Hardness
Calcite (left) has a hardness of 3 and a copper penny just scratches it.
Fluorite has a hardness of 4 and it can be scratched by an iron or brass nail.

34. Feldspar has a hardness of 6 and it will scratch a window glass.
Apatite (left) has a hardness of 5 and can be scratched by a steel knife blade.
Feldspar has a hardness of 6 and it will scratch a window glass.

35. Topaz has a hardness of 8 and will scratch quartz.
Quartz (left), with a hardness of 7, is the hardest of the common minerals. It easily scratches hard glass and steel.
Topaz has a hardness of 8 and will scratch quartz.

36. Corundum (left) has a hardness of 9. Corundum will scratch topaz.
Diamond with its hardness of 10 can easily scratch the rest of the minerals.

37. Quiz
Break!

38. Does this mineral show cleavage or fracture?
Discuss the following!
Does this mineral show cleavage or fracture?
Of the four most common minerals, which is the highest hardness?

39. Pure gold can have a specific gravity as high as 19.3!
Specific gravity tells you how many times as dense as water the mineral is.
Pure gold can have a specific gravity as high as 19.3!

40. acid test
Calcite is calcium carbonate, CaCO3. If a drop of weak hydrochloric acid is placed on calcite, the acid bubbles as carbon dioxide is released.

41. Other Special Properties Magnetic Malleable Radioactive Flourescence
Taste

42. Can you think of a mineral that might be shaped or hammered?
Malleable
or Ductile
Minerals that can be hammered thin or shaped are said to show these properties.
Can you think of a mineral that might be shaped or hammered?

43. Gold would be a perfect example!

44. Magnetic
Some minerals that contain Iron, are magnetic and can be picked up by a magnet.

45. This is the state of glowing while under a ultraviolet light.
Fluorescence
This is the state of glowing while under a ultraviolet light.
Some minerals even glow once the light is turned off!

46. Some minerals, such as this uraninite, are radioactive.
They give off subatomic particles that will activate a Geiger counter.

47. Halite (rock salt) can be identified by its taste.
This practice is not recommended!

48. Chemistry and Mineral Properties-Hardness
The stronger the bond, the Harder the mineral
Covalent bonds are the usually the hardest minerals; van der Waals are the softest minerals
3D structures are harder than 2D structures
Minerals with water in their structure are generally softer
Larger the cation & anion Longer the bond, the softer the mineral

49. Chemistry and Mineral Properties-Density
The harder the mineral, the more dense it usually is

50. Chemistry and Mineral Properties-Color
The most common cause of color in minerals is interaction with light outer-shell electrons.
Minerals of Hard cations (no outer shell electrons) have no color and are white or clear
Minerals of Soft cations (a few outer-shell electrons) commonly have colors unique to the cation. (Hematite: Fe+3 is red)

52. Color of Minerals

54. Uses of Minerals

56. 2.9 Million Pounds! Lead: 777 lbs Iron: 14, 530 lbs Zinc: 544 lbs
Clays: 12,121 lbs
Copper: 932 lbs
Salt: 31,779 lbs
Aluminum: 4,040 lbs
Stone, sand, & gravel: 1.11 million lbs

57. Common uses include: http://www.mii.org/commonminerals.php
Aluminum--packaging, transport, building
Beryllium--gemstones, fluorescent lights
Copper--electric cables, wires, switches
Feldspar--glass and ceramics
Iron--buildings, automobiles, magnets
Calcite--toothpaste, construction

58. Birthstones January: Garnet February: Amethyst March: Aquamarine
April: Diamond
May: Emerald
June: Pearl & Alexandrite
July: Ruby
August: Peridot
September: Saphhire
October: Tourmaline & Opal
November: Topaz and Citrine
December: Tanzanite, Zircon, & Turquoise

59. Fireworks Red: Strontrium Orange: mixture of Strontrium and Sodium
Americans use 30,000 tons of fireworks per year! Lets look at the minerals that make up the colors of fireworks
Red: Strontrium
Orange: mixture of Strontrium and Sodium
Yellow: sodium
Gold sparks: iron fillings and charcoal
Bright Flashes: Aluminum Powder
Green: Barium
Blues: Copper
Lavender: mixture of copper and strontium
Silver/White: mixture of titanium, zirconium, and magnesium
Silver/white flashes: Magnalium

60. Time for some research!
For homework, you will be doing the Mineral Mania Project
Use the following websites to get the information not covered in class:
for minerals in the home
for uses of common minerals
Ask me if you need print outs of the website!