A is naturally occurring, inorganic, and has a fixed composition and a repeating internal structure. Rocks are made of …

3.3

Elements are the building materials of minerals…. • Atomic structure

c.f. 3.5 3.4

Ionic bonds result from the transfer of an electron… is a perfect example of an ionic solid…

Halite

c.f. 3.7 3.12

1

• Covalent bonds result from sharing of Diamond and graphite are examples of ‘native’ carbon… electrons….

Elemental carbon, as diamond, is a perfect example of a covalently- bonded material. 3.15

Metallic bonding Structure of minerals

• Polymorphs • Minerals with the same composition but different crystalline structures • Examples include diamond and graphite » Phase change = one polymorph changing into another

‘Native’ ….

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: :

Mohs scale of hardness

Figure 3.22 Figure 3.20

Fluorite, halite, and calcite and muscovite Physical properties all exhibit perfect cleavage of minerals • • 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

Physical properties Conchoidal fracture 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

Silicate Two Minerals illustrations of the Si–O Silica tetrahedron tetrahedra link to form:

Figure 3.27

3.29

Chapter 4

Table 3.2

4