Chapter 5 Section 1 Notes
What is a Mineral?
- mineral – a natural, inorganic solid that has a
characteristic chemical composition, an orderly internal
structure and a characteristic set of physical properties
Characteristics of Minerals
- four questions to determine a mineral
- Table 1 Page 103
o Is it inorganic?
o Does it occur naturally?
o Is it a crystalline solid?
o Does it have a consistent chemical composition?
- answers must be “Yes” to all to be considered a mineral
Kinds of Minerals
- over 3000 minerals
- fewer than 20 are common
- rock forming minerals – common minerals that form the
rocks that make up Earth’s crust
- 10 are so common, they make up 90% of Earth’s crust
o quartz, orthoclase, plagioclase, muscovite, biotite,
calcite, dolomite, halite, gypsum, and
ferromagnesian minerals (contains iron and/or
magnesium)
Silicate Minerals
- silicate mineral – a mineral that contains a combination
of silicon and oxygen and they may also contain one or
more metals
- quartz has only silicon and oxygen
- feldspars are the most common
- make up 96% of Earth’s crust
Nonsilicate Minerals
- nonsilicate minerals – a mineral that does not contain
compounds of silicon and oxygen
- make up 4% of Earth’s crust
- six major groups
o carbonates, halides, native elements, oxides, sulfates
and sulfides
Crystalline Structure
- all minerals have a crystalline structure
- crystal – a solid whose atoms, ion or molecules are
arranged in a regular, repeating pattern
- scientists use X-rays to study the structure of crystals
Crystalline Structure of Silicate Minerals
- each building block has four oxygen atoms arranged ina
pyramid with one silicon atom in the center
- silicon-oxygen tetrahedron – the basic unit of the
structure of silicate minerals; a silicon ion chemically
bonded to and surrounded by four oxygen ions
- six kinds of silicate-mineral arrangements (Fig 3 pg 107)
o isolated tetrahedra – individual tetrahedra do not
link with other silicon or oxygen atoms
o ring silicates – tetrahedra form a ring by sharing
oxygen atoms
o single-chain silicates – tetrahedra form a chainby
sharing oxygen atoms
o double-chain silicates – form when two sing chains
of tetrahedra bond to each other
o sheet silicates – form when each tetrahedron shares
three of its oxygen atoms with other tetrahedra
o framework silicates – form when each tetrahedra is
bonded to four other tetrahedra
The Crystalline Structure of Nonsilicate Minerals
- display a vast variety of crystalline structures
- forms cubes, hexagonal prisms and irregular masses
- structure of the crystal determines characteristics
- native elements have very high densities
o occurs because of closest packing
o each metal atom is surrounded by 8 to 12 other
metal atoms that are as close to each other as the
charges of the atomic nuclei will allow