Download A mineral is naturally occurring, inorganic, and has a fixed

A mineral is naturally occurring, inorganic, and
has a fixed composition and a repeating internal
structure.
Rocks are
made of
minerals…
3.3
Elements are the building materials of minerals….
3.4
Ionic bonds result from the transfer of an electron…
• Atomic structure
c.f. 3.5
Halite is a perfect example of an ionic solid…
Halite
c.f. 3.7
3.12
1
• Covalent bonds result from sharing of
electrons….
Elemental carbon, as
diamond, is a perfect
example of a covalentlybonded material.
Structure of minerals
Diamond and graphite are examples of ‘native’ carbon…
3.15
Metallic bonding
• Polymorphs
• Minerals with the same composition but
different crystalline structures
• Examples include diamond and
graphite
» Phase change = one polymorph
changing into another
‘Native’ copper….
Physical Properties of Minerals:
Color:
• Crystal form
Quartz (SiO2) exhibits a variety of colors
• External expression of a mineral’s internal structure
Figure 3.26
2
Hardness:
Cleavage:
Mohs scale
of
hardness
Figure 3.22
Figure 3.20
Fluorite, halite, and calcite and muscovite
all exhibit perfect cleavage
Physical properties
of minerals
• Fracture
• Absence of cleavage when a mineral
is broken
• Specific Gravity
• Weight of a mineral / weight of an
equal volume of water
• Average value = 2.7
Conchoidal fracture
Physical properties
of minerals
• Other properties
• Magnetism
• Reaction to hydrochloric acid
• Malleability
• Double refraction
• Taste
• Smell
• Elasticity
Figure 3.23
3
Elemental abundances
in continental crust
Mineral groups
• Silicates
• Most important mineral group
– Comprise most rock-forming minerals
– Very abundant due to large % of silicon and
oxygen in Earth’s crust
• Silicon-oxygen tetrahedron
– Fundamental building block
– Four oxygen ions surrounding a much smaller
silicon ion
c.f. 3.26
Two
illustrations
of the
Si–O
tetrahedron
Silicate
Minerals
Silica
tetrahedra
link to form:
Figure 3.27
3.29
Chapter 4
Table 3.2
4