1. Atoms to Minerals
Matter
And
Atoms
Chapter 5 section 1

2. What is matter? Matter is anything that has mass and volume.
Mass-the amount of material in a substance
Volume-the amount of space taken up by an object or substance.
Minerals are made of matter because they have mass and volume.

3. What makes up matter? Matter is composed of elements.
Element = a substance that cannot be broken into simpler substances by ordinary chemical means.
Ex. oxygen, carbon, nitrogen, hydrogen, silicon, gold
Represented by a symbol (as well as name)
Elements are made of atoms
Atoms are the smallest part of an element that has all the element’s properties

4. Structure of an Atom Central region called the nucleus Electrons
Consists of protons (positive charges) and neutrons (neutral/no charge)
Most of the mass of an atom
Electrons
Negatively charged particles that orbit around the nucleus
Located in discrete energy levels called shells
Often called an electron “cloud”
In its neutral state, an atom has an equal number of protons and electrons…so, it has no charge.

5. An Atom
Atoms consist mostly of empty space (between the nucleus & its surrounding electrons).

6. Flattened structure of an atom
# protons (+) equals # electrons (-) Electrons in shells
Number of outermost electrons determine types of bonding
Argon
Outermost (Valence) shell

7. Some definitions:
Atomic number: number of protons in the nucleus (= to the # of electrons in the atom)
Atomic Mass: total mass of protons and neutrons within an atom’s nucleus
The # of protons and electrons in an atom determines its properties.

8. Electrons and Energy Levels
As the # of electrons in atoms increases, more energy levels are needed to hold them.
greatest # of energy levels = 7
Each level can hold only a specific number of electrons.

9. Classifying Atoms
The periodic table is a tool used to organize information about the elements.
In rows from left to right # of protons increases
In vertical (up and down) columns, also called groups, elements have similar chemical properties.

10. Column shows # electrons in outermost shell
Periodic Table of the Elements
Shows atomic number (# protons) and atomic mass (# protons + neutrons).
Column shows # electrons in outermost shell

11. Isotopes The identity of an atom depends on the # of protons.
Elements that have the same # of protons, but a different # of neutrons (and therefore different masses) are called isotopes
Mass # of isotope is equal to the # of protons plus the # of neutrons (mass # = #p + #n)
Often used in geologic dating.

12. Bonding of Atoms
Most substances on Earth are not pure elements, but rather compounds.
Compounds contain 2 or more elements that are chemically combined
Atoms are most stable when their outermost energy levels are filled (with electrons)
Stable atoms do not readily combine with other elements to form compounds

13. Bonding of Atoms
Atoms (with shells that are not full) try to fill their outermost shell by gaining, losing, or sharing electrons.
This forms a chemical bond that hold atoms together.
3 main bond types:
1. covalent
2. ionic
3. metallic

14. Covalent Bonds Some compounds form when atoms share electrons.
Two or more atoms held together by covalent bonds form a molecule.

15. Ionic Bonds
Other compounds are held together by the force of electrical attraction between atoms that have lost or gained electrons.
loses electron  positive charge.
gains an electron  negative charge.
charged atom is called an ion
Ions with opposite charges attract, forming compounds with ionic bonds.
Common in many minerals

16. Metals and Nonmetals
Metal = element that loses electrons easily to form positive ions
Ex. sodium, potassium, gold (much of periodic table)
Ionic bonds don’t form between metals
Non-metal = element that gains electrons easily to form negative ions
Ex. chlorine, oxygen, nitrogen (right side of periodic table)
Ionic bonds can form between non-metals
Bonds form easily between metals and nonmetals

17. Metallic Bonds Formed between metal atoms
Different characteristics than bonds that form between metal and nonmetal atoms
Electrons move freely around metal ions

18. Compounds and Mixtures
Can have properties unlike those of the elements from which it is made
Elements combine in a fixed proportion
Can only be separated by chemical means (electricity)
Ex. water hydrogen, and oxygen
Ex. salt sodium, and chlorine
Mixtures
Individual elements (or compounds) keep their own properties
Elements/compounds can be present in any proportion
Most can be separated by physical means (evaporation)
Ex. salt water

19. Composition and Structure of Minerals
Chapter 5 Section 2

20. What is a mineral? …a naturally occurring, solid, inorganic substance
that has a definite
chemical composition & molecular structure

21. The 5 “must haves” to be classified a MINERAL
Mineral Criteria
The 5 “must haves” to be classified a MINERAL

22. 1. Naturally Occurring A mineral cannot be man-made!!!
It must be formed in nature.

23. 2. Solid Matter A mineral MUST BE A SOLID (not a liquid or a gas)!
Minerals can be crushed into powder, which is still a solid!

24. 3. Definite Chemical Composition
Each mineral has a chemical composition – a “Recipe” for making that mineral. Change the recipe and you change the mineral!

25. 4. Atoms Arranged in an Orderly Pattern
When the atoms combine, they must form a PATTERN (crystalline structure)

26. 5. INORGANIC
A mineral CANNOT be made from anything that is, was, or will be living!
EXCEPTION
Shells are PRODUCED by living things (but the shells themselves are not alive).

27. Most minerals are compounds (elements combine in a fixed proportion).
Quartz
Compound of silicon and oxygen
Galena
Compound of lead and sulfur
Minerals made of single elements are called native elements.
Silver, copper, sulfur, diamond, graphite

28. Common Mineral Forming Elements Found in Earth’s Crust
(by mass)

29. How do minerals form?
1. Solidification of molten materials
*atoms, molecules, & ions move closer together & form compounds
*minerals that form depend on the types & amounts of elements present
*rate of cooling affects size of mineral grains
2. Evaporation of seawater
*as water molecules evaporate, dissolved ions bond to form minerals (ex. halite)
3. Transformation by heat, pressure, or chemical action

30. Structure of Minerals: Crystal Structure
All minerals have CRYSTALLINE STRUCTUrE (internal arrangement of atoms)
**The internal arrangement of atoms affects the mineral’s physical properties, especially shape, hardness and cleavage/fracture.**
repeated in three dimensions
halite

31. Crystal Faces
Some minerals actually form “crystals” (a regular geometric solid with smooth surfaces called crystal faces)
However, there may not be enough room for crystal faces to develop fully, or “grow.” The mineral just fills the available space.
The mineral is still crystalline, but crystal faces are not visible.

32. 6 Basic Crystal Shapes
The angle between crystal faces is characteristic for
each type of mineral and can be used in identification.
Systems
Examples

33. Silicates Most minerals are composed of only 8 elements!
Silicon Oxygen Tetrahedron Animation
O2 -
Si4+
The Silicon-Oxygen
Tetrahedron—an
example of ionic bonding.
Most minerals are composed of only 8 elements!
Silicon and oxygen are the two most abundant elements in Earth’s crust.
90+% minerals (and, therefore, rocks) contain these elements.

34. Crystal Structure & Physical Properties
Minerals are solids due to crystalline structure.
Crystal structure determines a mineral’s cleavage (tendency to split along definite planes).
Cleavage planes correspond to planes of weak bonds between the atoms, ions, or molecules.
The hardness of a mineral also depends on the internal arrangement of atoms. (ex. diamond and graphite)

35. are both pure carbon, but have different molecular structures.
Example
Diamond and Graphite
are both pure carbon, but have
different molecular structures.

36. Identifying Minerals
Mineralogy: the study of minerals and their properties.
Many minerals can be identified & classified by inspecting them visually and performing simple tests to determine their properties.
Chapter 5 Section 3

37. Rock-Forming Minerals
Most rock-forming minerals are silicates.
Common rock-forming minerals.
Clay Quartz Calcite Olivine Dolomite Pyroxene Amphibole Biotite and Muscovite Micas Orthoclase and Plagioclase Feldspars

38. Identifying Minerals by Inspection
Observed properties should be considered together. A mineral is rarely identified by a single property.

39. Physical Properties of Minerals
Color
Most easily observed property
Some minerals have distinctive colors, but color is generally unreliable for identification because impurities or oxidation (exposure to oxygen in air/water) can change a mineral’s color
Exotic colorations of some minerals produce gemstones.
However, we still use color as one of the many properties for mineral identification.

40. Quartz (SiO2) exhibits a variety of colors.
milky quartz
citrine
amethyst
smoky
quartz

41. From:geology.csupomona.edu/alert/mineral/minerals.htm

42. Luster The way a mineral’s surface reflects light
“metallic” or “nonmetallic”
Nonmetallic luster:
Adamantine – brilliant, like a diamond
Dull - non-reflective surface
Earthy - look of dirt or dried mud
Fibrous - the look of fibers/strings
Greasy/oily - the look of grease
Pearly - the look of a pearl
Resinous - the look of resins such as dried glue or chewing gum
Silky - the look of silk, similar to fibrous but more compact
Vitreous - the look of glass (most common)
Waxy - the look of wax

43. Galena is a lead sulfide that displays metallic luster

44. Pyrite is an iron sulfide that displays metallic luster

45. Examples of Nonmetallic Luster
adamantine
Examples of Nonmetallic Luster
resinous
fibrous
silky
dull
greasy/oily
vitreous/glassy
earthy
pearly
waxy

46. Testing Mineral Samples

47. Streak
Color of a mineral in its powdered form when it is rubbed on a “streak plate” (unglazed porcelain)
May be same as hand-specimen or different
Helpful in distinguishing different forms of the same mineral
Streaks of nonmetallic minerals are usually colorless or white
ALWAYS place streak plate on a flat surface.
Never hold it in your hand.
It can break and cut you.

48. Examples of Streak

49. Cleavage Tendency to break along planes of weak bonding
Flat, shiny surfaces (1, 2, 3, 4, 6 common)
Described by resulting geometric shapes
Number of planes
Angles between
adjacent planes
Cleavage Plane Animation

50. Examples of cleavage – fluorite, halite, and calcite

51. Mica – one plane of cleavage
Muscovite

52. Fracture When minerals break unevenly along rough or curved surfaces.
Conchoidal
fracture

53. Mineral Hardness
The ease or difficulty with which the mineral can be scratched
Controlled by the strength of bonds between atoms
All minerals are compared to a standard scale called the Mohs scale of hardness
Range from 1—talc (softest) to 10—diamond (hardest)

54. Mohs Scale of Hardness
Softest
Hardest
Steel file

55. Determining Mineral Hardness
You can determine the approximate hardness of any common mineral by using your fingernail, a copper penny, a small glass (“scratch”) plate, and a steel file.
See whether the mineral scratches or is scratched by each item.
If the mineral scratches the item, it is harder than that item.
If the mineral is scratched by the item, it is softer than the item.
This will tell you the mineral’s approximate hardness.
Ex. If the mineral scratches the glass plate (5.5) but is scratched by the steel file (6.5), its hardness is between 5.5 and 6.5 on the Mohs Scale.

56. Specific Gravity/Density
All minerals have density (mass / volume), but some are very dense.
Examples: galena, magnetite, and gold.
Specific gravity is the density of the mineral compared with the density of water.

57. Special Properties Double refraction Fluorescence Taste Magnetism
Radioactivity
Reaction to hydrochloric acid
Odor (smell)

58. Double Refraction
“Seeing
double”

59. Fluorescence
en.wikipedia.org
Some minerals will glow when placed under short-wave or long-wave ultraviolet rays (“black-light”)
Franklin and Ogdensburg, NJ are famous for their fluorescent minerals

60. Taste Halite tastes salty.
Remember…do not taste anything in the laboratory.

61. Magnetism
Many iron minerals will produce an invisible magnetic force field.
“Lodestone” acts like a magnet.
Magnetite is attracted to a magnet.

62. Radioactivity
Give off subatomic particles that can be detected by a Geiger counter.
Exposure can be dangerous to living organisms.

63. The “Acid Test Reaction with HCl”
Carbonates react with dilute HCl and other acids by fizzing or bubbling (releasing CO2 gas)

64. Chemical Reactions: Is it calcite or dolomite?

65. Odor
Sulfur smells like rotten eggs.

66. Mineral Groups
Chapter 5 Section 4

67. Major Silicates More than 90% of minerals in Earth’s crust
Silicon + Oxygen (and usually 1 or more metallic elements)
Basic building block = silicon oxygen tetrahedron
Four oxygen ions surrounding a much smaller silicon ion
Classified by how the tetrahedra are linked together

68. Silicate Molecule The Silicon-Oxygen Tetrahedron
The basis of most rock-forming minerals

69. Silicate Mineral Examples
Mica
Feldspar
Olivine
Quartz
Pyroxene

70. Quartz Made entirely of tightly bound silica tetrahedra
SiO2 (silicon dioxide)
Glassy or greasy luster, colorless/white/or variety of colors, conchoidal or irregular fracture, hardness = 7
Uses: watch movements, prisms, heat lamps, lenses, glass, paints, jewelry
Common rock-forming mineral (ex. granite)
2nd most abundant mineral in Earth’s crust
Main component of most sands

71. Example:
Quartz
SiO2
(3-D, Also the Feldspars)

72. Feldspars
All types of feldspars have 2 directions of cleavage, hardness = 6, pearly luster
Used in glass, ceramics
Also has aluminum in addition to silicon and oxygen…
Other metals include potassium, sodium, calcium
Important rock-forming minerals
Make up ~60% of Earth’s crust

73. Feldspars Classified into 2 major groups:
potassium feldspars (k-spar, microcline)
Orthoclase most common (pink/salmon, cleavage 2 directions at 90°, most commonly found in granite)
Sodium-calcium feldspars (also known as plagioclase feldspar, plag)
examples: oligoclase, albite, labradorite (white to gray, cleavage 2 directions nearly 90°, striations/fine parallel lines)

74. Feldspar
Aluminum atoms (yellow) with nearby Sodium atoms (green) to balance charge

75. Other Silicates Pyroxene family Mica family Cleavage nearly 90°
Augite most common of pyroxene family (contain iron and magnesium, dark color, 2 good cleavages, hardness between 5 & 6)
Mica family
Soft silicates (hardness = 2.5)
Perfect cleavage in 1 direction (sheets/flakes)
Common in granite and gneiss
Muscovite (silvery/white)
Biotite (dark brown/black)
Used in electronics insulators, paints, plastics, rubber, roofing

76. Single chains weakly paired
Oxygens share electrons
with two Silicon atoms
Positive ion
2_26b
Example: A Pyroxene
Cleavage planes about 90o
Single chains weakly paired

77. Example: A Mica
Sheet silicates

78. Other Silicates Amphibole minerals Olivine group
Form long, needlelike crystals
Most common amphibole is hornblende (iron and magnesium, shiny dark green/brown/black, hardness 5-6, 2 good cleavages at more than 90°, found in igneous and metamorphic rocks)
Olivine group
Olive green
Ferromagnesian silicate (iron, magnesium, silicon, oxygen), hardness = 6.5, glassy/shell-like fracture, gem-quality olivine = peridot, found in some meteorites)

79. Example: An Amphibole Cleavages 56 and 124 degrees Positive ion
Double chains
2_26c
Cleavages 56 and 124 degrees

80. Example OLIVINE Positive ion Fe and Mg SiO4 -4 Ion Tetrahedron
facing down
facing up
Positive ion
Fe and Mg
SiO4 -4 Ion
Independent tetrahedra

81. Other Silicates Kaolinite Aluminum silicate
Formed by weathering of feldspars and other silicates
White, hardness = about 2, perfect cleavage in 1 direction
Often used in ceramics, paints, fiberglass

82. Clay Minerals (at high magnification)
note sheet structure
Kaolinite (hand specimen)

84. Common Non-silicate Minerals
Many non-silicate minerals have economic value

85. Carbonates Carbonates contain CO3 (carbonate) and metal ions
Contained in limestone, marble, and dolostone
Many uses (building materials, manufacturing of paper and medicines)
Calcite (calcium carbonate) and Dolomite (calcium-magnesium carbonate) are the two most important carbonate minerals

86. Calcite and Dolomite Calcite = CaCO3 Calcium carbonate Dolomite
Colorless or white, hardness = 3, 3 perfect cleavages at more than 90° (rhombohedra), bubbles with acid
Dolomite
Calcium magnesium carbonate
Hardness 3.5-4, cleaves into rhombohedra, bubbles in acid only if powdered first
Coarse or fine grains in dolomitic limestone

87. Oxides and Sulfides Contain significant amounts of iron
Not as common as silicates or carbonates
Economically important
Used to make steel, magnets, car parts, medicines, cosmetics, plastics, paints
Iron usually combined with oxygen (oxide) or sulfur (sulfide)

88. Oxides and Sulfides Oxides Sulfides Hematite Magnetite
Most common iron oxide
Usually red (sometimes silvery/metallic), earthy luster, uneven fracture, red-brown streak, hardness 5-6
Magnetite
Black iron oxide
Attracted to a magnet
Lodestone is a variety of magnetite (is a natural magnet)
Hardness
Sulfides
-Pyrite “fool’s gold”
-Most common sulfide mineral
-Iron sulfide
-Pale brass to golden yellow
-Hardness ≈ 6
-6-12 sided crystals

89. Nonsilicate Mineral Examples
Spinel
(Oxide)
Halite
(Halide)
Gypsum
(Sulfate)
Hematite
(Oxide)
Calcite
(Carbonate)
Pyrite
(Sulfide)
Galena
(Sulfide)