1. Minerals Pt. 2

2. Minerals
1. Physical properties of minerals
2. Mineral groups

3. Building Blocks Of Minerals
What is a Mineral?
A naturally occurring inorganic solid with a definite chemical composition and molecular structure.
Minerals can consist of elements or compounds. Majority are compounds. Example Galena (PbS) and Pyrite (FeS2)
Native Minerals consist of only one type of element. Examples include Gold, Silver, Sulfur, Diamond, Copper.
To be a mineral a substance must satisfy the following:
1) Occur in nature
4) Definite chemical composition
2) Inorganic
5) Definite molecular structure
3) Solid

4. Building Blocks Of Minerals
What materials make up minerals?
Elements:
Names and Symbols of elements found in common minerals include:
1) Chlorine (Cl) 2) Calcium (Ca) 3) Carbon (C) 4) Aluminum (Al) 5) Copper (Cu) 6) Cobalt (Co) 7) Fluorine (F) 8) Gold (Au) ) Hydrogen (H) 10) Iron (Fe) 11) Lead (Pb) 12) Magnesium (Mg) 13) Oxygen (O) 14) Nitrogen (N) 15) Nickel (Ni) 16) Manganese (Mn) 17) Silicon (Si) 18) Sodium (Na) 19) Silver (Ag) 20) Potassium (K) 21) Sulfur (S) 22) Tin (Sn) 23) Zinc (Zn)
For Example:
Halite – NaCl,
Galena – PbS,
Hematite - Fe2O3

5. Mineral Groups in the Earth’s Crust
7 main mineral groups are:
Silicates (Si + O)
Carbonates (C + O)
Sulfates (S + O)
Oxides (metal + O)
Halides (metal + halogen)
Sulfides (metal + S)
Native elements (Consist of only one type of element. Examples: Gold, Silver, Sulfur, Diamond, Copper)

6. The two most abundant elements: Silicon (Si) Oxygen (O)
Over 4000 minerals, but only a few dozen are considered rock forming minerals.
Only 8 elements make up most of crust’s minerals & represent over 98% of the continental crust
Ottawa Senators Are Insane, Calgary Should Play Montreal
Oxygen, Silicon, Aluminum, Iron, Calcium, Potassium, Magnesium
The two most abundant elements:
Silicon (Si)
Oxygen (O)

7. Average composition of the continental crust
Mineral groups
Percent of elements by WEIGHT
Average composition of the continental crust

8. Average composition of the continental crust
Mineral groups
Percent of elements by VOLUME
Average composition of the continental crust

9. Mineral groups Light colored (crust, esp. continental crust)
Most Common Minerals
Light colored (crust, esp. continental crust)
Quartz (SiO2) - commonly transparent
Feldspar (Si, O, Al, K, Na, Ca) - mostly white or pink
Clay (same stuff as feldspar, with water)
Calcite (CaCO3, shells) limestone - make cement
Dark colored (mantle and oceanic crust)
Olivine (Si, O, Fe, Mg, Ca)
Earth’s Crust
mostly Si, O

10. Mineral Group #1: Silicates
The building block of all silicates is the
silicon-oxygen tetrahedron
SiO4
Two different views of this arrangement:
silicon atom
oxygen atoms

11. SiO SiO O Si electric charges of tetrahedra ions: 1 silicon (Si) atom
4 oxygen (O) atoms Si 4+ O 2-
SiO 4
Silicon tetrahedron has
charge of -4
SiO 4 4-

12. Every silicate mineral contains the elements
silicon (Si) + oxygen (O)
Most silicates combine with other elements (i.e. positively charged cations) to make a stable structure.

13. Silicates aren’t electrically neutral
They’re neutralized by certain metallic ions, such as:
iron (Fe)
magnesium (Mg)
potassium (K)
sodium (Na)
aluminum (Al)
calcium (Ca)

14. Mineral groups
The silicates

15. Tetrahedra can join: A single tetrahedron Two tetrahedra joined
by a common oxygen
atom

17. Sialic Silicates Simatic silicates
Because silicates make up about 96% of the earths crust, it has been subdivided into TWO groups:
Sialic Silicates
Simatic silicates

18. Sialic Silicates rich in silicon and aluminum.
main rock type found in continents and comprise about 85% of the crust.
mineral are light in color
Examples: Muscovite has a pearly lustre

19. Muscovite

20. Simatic Silicates rich in silicon and magnesium.
main rock type found in the ocean floor and comprise less than 15% of the crust.
mineral are dark in color
Example: Olivine, pyroxenes, hornblende, biotite, garnet

21. Olivine
Biotite
Hornblende
Garnet

22. Carbonates- contain the carbonate molecule CO3
Mineral groups
Important Nonsilicate Minerals
Carbonates- contain the carbonate molecule CO3
Calcite (CaCO3)
Dolomite (CaMg(CO3)2
 found together in sedimentary rock limestone,
 Main ingredient to cement, roads & building stones

23. Mineral groups
Important Nonsilicate Minerals
Oxides compounds consisting of an atomic structure of oxygen combined with one or more metals.
Hematite (Fe2O3) Bauxite (Al2O3),
-> steel
Sulfides- compounds consisting of an atomic structure of one or more metals combined with sulfur.
Examples: Pyrite (FeS2), Galena (PbS), Sphalerite (ZnS).

24. Mineral groups
Important Nonsilicate Minerals
Halides- compounds consisting of an atomic structure of chlorine(Cl) or fluorine(F) with sodium(Na), potassium(K), or calcium(Ca).
Ex: Halite (NaCl)
-> common table salt
Sulfates compounds consisting of an atomic structure of one sulfur and four oxygen (SO4).
Ex: Gypsum (CaSO4 .H2O)
-> main ingredient of
plaster & other building materials

25. Native Minerals- elements that occur uncombined in nature.
Mineral groups
Important Nonsilicate Minerals
Native Minerals- elements that occur uncombined in nature.
commonly called native elements.
Examples: Gold (Au), Silver (Ag), Copper (Cu), & Sulfur (S)

26. Hints to Classify Mineral Groups
Olivine (Mg,Fe)2SiO4
Barite BaSO4
Calcite CaCO3
Mineral groups that end with “ate” and have an oxygen group in its chemical formula are one of the following;
Silicates = Si + Ox
Sulfates = S + Ox
Carbonates = C + Ox

27. Hints to Classify Mineral Groups
Hematite Fe2O3
Pyrite FeS2
Fluorite CaF2
Mineral groups that end with “ide” and have a metal (eg. Na, K) in its chemical formula are one of the following;
Oxidides = Metal + O
Sulfides = Metal + S
Halides = Metal + Cl, Br, F

28. Physical properties of minerals
We use physical properties of minerals to identify them
Crystal form
Luster
Color
Hardness
Cleavage
Fracture
Specific gravity
Taste
Elasticity
Feel
Magnetization
Optical properties
Smell
Streak

29. The properties of each mineral depends on the following;
Physical properties of minerals
The properties of each mineral depends on the following;
1) The type of elements present
2) The arrangement of atoms
3) The strength of bonding

30. Quartz (SiO2) Crystal form
Shape of a crystal can reflect the orderly internal arrangement of atoms
Quartz
(SiO2)

31. Crystal form
Shape of a crystal can reflect the orderly internal arrangement of atoms

32. The sooth flat surfaces on crystals are called faces.
Crystal form
The sooth flat surfaces on crystals are called faces.
Shape of a crystal can reflect the orderly internal arrangement of atoms

33. The appearance of the mineral in reflected light.
Luster
The appearance of the mineral in reflected light.
A metallic looking mineral: metallic luster
Others: nonmetallic luster
Ex: pearly, silky, glassy, adamantine,
greasy, earthy.

34. Metallic Luster

35. Non-metallic Glassy Luster
B) Greasy
A) Glassy

36. D) Pearly
C) Earthy . or Dull

37. One mineral can come in many colors.
Obvious, but often misleading. Slight impurities in a mineral can change its color.
Problems:
One mineral can come in many colors.
Different minerals can have the same color.
Surface oxidation can change a minerals color.

38. Color
Quartz (when pure it is colorless):

40. Various blue minerals

41. Surface Oxidation

42. Streak The true color of the mineral in its powdered form.
To find the streak of a mineral, you perform a streak test. To do this you scratch a mineral across an unglazed porcelain tile and the powder streak left on the tile is the true color of the mineral.

43. Hardness- The resistance of a mineral to scratching.

44. Hardness is expressed in terms of Moh’s Hardness Scale which ranks relative hardness from 1 – 10.

45. If the object scratches the mineral then it is harder than the mineral.

47. Calcite Mica (sheets) Cleavage
Tendency of a mineral to break along weak planes of bonding in crystal structure (some bonds are stronger than others)
Calcite
Mica (sheets)

48. Cleavage
Cleavage directions are determined by atomic structure and strength of bonding.

49. Cleavage
Cleavage follows areas of weak bonding.

50. Cleavage Plane Directions
Minerals show cleavage in many different directions, but most common are in planes of one, two, and three directions.
Cleavage in one direction (Basal Cleavage). Example: Mica displays this type of cleavage.

51. Cleavage Plane Directions
Cleavage in two directions. Example: Orthoclase feldspar displays this type of cleavage.

52. Cleavage Plane Directions
Cleavage in three directions. Example: Halite displays this type of cleavage.

53. Tendency of a mineral to break irregularly.
Fracture
Tendency of a mineral to break irregularly.
Conchoidal Fracture is a curved breakage that resembles the concentric shape of a mussel shell. It often occurs in fine-grained minerals or in crystalline minerals

54. Specific gravity
is the mass of a mineral compared to that of an equal volume of water
1.) weigh the specimen in air and record the weight.

55. 2.) weigh the specimen submerged in water and record the weight.
3.) calculate specific gravity (S.G.) using the following formula.
Specific Gravity = weight in air weight in air - weight in water

56. Specific Gravity = Density
Because pure water at 4EC has a density of 1 g/cm3, the specific gravity is equal to its density Thus; Specific gravity = Density.
Metric system 1ml = 1gram= 1 cm3
To determine Density you need to:
1) Use a scale to measure the mass of the mineral sample.
2) Find the volume of the mineral sample.
3) Calculate density (which equals specific gravity).
Density = Mass(mineral) Volume(mineral)
= Specific Gravity

57. Specific Gravity
Given: 1mL = 1cm3 = 1g, we know the weight of an equal volume of water in grams. We can then use the following formula to calculate Specific Gravity:
Calculation
S.G. = W(mineral) W(water)

58. Other Properties
Taste
Elasticity
Feel
Magnetization
Optical properties
Smell
Acid test
Double refraction
Fluorescence
Acid Test - drop acid on the sample to see if the mineral reacts (fizzes). used to test the Carbonate group. Ex. Calcite (Limestone)