1. BASIC GEOLOGY
Chapter 2 :
Atoms to
Minerals

2. Normal Matter is composed of…….
Atoms

3. But not all atoms are the same!
Atoms differ in the number of “pieces” ( Protons, Neutrons and Electrons) that they have inside of them.

4. Atoms with certain consistent characteristics are called….
Elements

5. An Element is...
matter that is made up of atoms (or one atom) that have the same number of Protons in their nucleus.
matter that is made up of atoms…

6. Not all atoms of the same element are the same, either.
But!!!
Not all atoms of the same element are the same, either.

7. Atoms of the same element that have different numbers of neutrons in their nuclei are called….
Isotopes

9. Certain isotopes of elements are unstable, or radioactive
Certain isotopes of elements are unstable, or radioactive. (example: Carbon-14 and Uranium-238)
These radioactive isotopes of elements allow us to do absolute-age dating!

10. Most substances on Earth are not pure elements but rather….
???
Compounds

11. What is a Compound?

12. A Compound is…..
A substance made from two or more different elements that have been chemically combined.

13. A Mixture, on the other hand, is…
A substance made from two or more different elements that have not been chemically combined, and which can be separated by physical means

14. Mixtures

15. Elements by themselves are much less common than Compounds, because they tend to combine with each other to form Compounds.

16. Elements and Compounds in their solid form make up…
Minerals

17. What is a Mineral???
What is a Mineral?

18. A Mineral is a naturally occurring Inorganic Solid with a definite chemical composition and a crystalline structure.

19. That means that… It can’t be organic in origin It can’t be a liquid
and..
It has to have a crystal structure

20. Lets put that in a list format.
1. Minerals are a naturally occurring substance.
2. Minerals are solids.
3. Minerals have a definite chemical composition.

21. 4. The atoms that make up minerals are arranged in an orderly pattern (They form crystals).
5. Minerals are inorganic. (They were never alive.)

22. How many different minerals are there on Earth???
Answer:
About 4,000

23. More than 90% of all of the minerals in the Earth’s Crust, however, are made up of compounds containing Silicon and Oxygen, the two most abundant elements on Earth.

24. The percent composition of Silicate
And…..
The percent composition of Silicate
Minerals in an igneous rock determine a lot of the characteristics of that rock and the magma that formed it.

25. High Silica content forms light-colored rocks.

26. While lower (but only by about 25%) Silica content forms darker-colored rocks.

27. How do Minerals Form???
1. Minerals form in cooling magma chambers

28. Different types of minerals crystallize at different temperatures
Decreasing temperature
Bowen’s Reaction Series
Mineral formation in a Magma Chamber

30. Olivine

31. Pyroxene

32. Peridotite- Mostly Olivine

33. Gabbro- Pyroxene and Olivine

39. Andesite- Hornblend and Biotite? and Plagioclase Feldspar

41. Potassium Feldspar

42. Quartz

43. Pink Granite

45. Mineral Fractionalization in a Magma Chamber

46. 2. Metamorphic Minerals: Some minerals occur as the result of Recrystallisation and Reaction within existing rocks which produces new minerals in response to changes in
Pressure
and
Heat

49. 3. Some types of minerals form as water containing dissolved ions slowly evaporates.
Salt deposits

50. How long does it take for minerals to form??
Minerals in solution in water can form relatively quickly when the water evaporates.
Minerals in magma can form as quickly as the magma/lava can crystallize (lava can cool in minutes, while magma can take thousands of years).

51. Crystalline Structure
Minerals have a
Crystalline Structure

52. A regular geometric solid with smooth surfaces called….
A Crystal is….
A regular geometric solid with smooth surfaces called….
Crystal Faces

53. The orderly arrangement of ions, molecules, or atoms, in any mineral determines the shape of its crystals.

54. Although there are thousands of different types of minerals, their crystals come in six basic types of shapes

55. Cubic

56. Orthorhombic

57. Tetragonal

58. Triclinic

59. Hexagonal

60. Monoclinic

61. Physical Properites
of Minerals

62. With all of the different types of minerals,
how do you identify them??

63. Luster
Hardness
Streak
Cleavage
Minerals are identified and classified by visual inspection, and by performing simple tests to determine their physical properties
Color
Specific Gravity
Fracture

64. Rock-Forming Minerals

65. Only 30 of the 4,000 known minerals are common.
These 30 minerals are known as the rock-forming minerals
Rock-Forming Minerals.

66. Most rock-forming minerals are…
Silicates
The percent composition of Silicate minerals in a rock determines the type of rock it is.

67. Rocks that have a high percentage of Silicates are light in color, and are called Felsic rocks.

68. Rocks that have a low percentage of Silicates are dark in color, and are called Mafic rocks.

69. Rocks are often made of several different minerals.

70. Identifying Minerals by Inspection

71. Minerals are most often identified by inspecting their Physical and Chemical properties.

72. Color
Color is the most easily observed, but least reliable property of a mineral for identification.
This is because the color of many minerals varies with the kind of impurities in the mineral.

74. Luster
Luster is the way in which a mineral shines in the light.

75. Types of Luster

85. Streak
Streak is the color of the powder left on a streak plate when a mineral is rubbed on it.
Streak is much more reliable than color because, although the color of a mineral changes, its streak does not.

87. Cleavage
Cleavage is the tendency of a mineral to split in a particular direction.

89. “Sheety” Cleavage

91. Feldspars always cleave readily at or near right angles.

92. Fracture
Fracture is the tendency of a mineral to break in directions other than along crystal faces or cleavage surfaces.

93. Conchoidal or shell-like fracture
Fibrous facture

94. Hardness Hardness is the resistance of a mineral to being scratched.
The Mohs Hardness Scale is one of the most effective tool for identifying minerals.