Transcript Minerals (Review)

Minerals (Review)
Terms
Mineral is:
• Naturally Occurring--Not man made.
• Crystalline: solids whose atoms are
arranged in a regular repeating pattern.
• Inorganic– Not derived form plants or
animals.
• Specific chemical composition: All
minerals have a specific chemical
composition within a specific range.
Types of chemical bonds
• Ionic: one atom gives away one or more
electrons to another atom. The giving
atom becomes a positive charged cation.
The receiving atom becomes negatively
charged anion. Since + and – attract each
other these atoms become bonded or
bound to each other. Example NaCl.
Types of chemical bonds
• Covalent: One atom shares some of its electrons
with one or more other atoms.
Example: diamond is the covalent bonding
of Carbon (C) atoms.
H2O (though a non mineral) is a good
example of covalent bonding. Oxygen has two
empty slot in outer most energy level, and
Hydrogen has one empty slot. To satisfy both
they end up sharing electrons and a covalent
bond results.
Types of chemical bonds
• Metallic: type of bonding found in metals.
Electrons are loosely bond to any specific
nucleus, and so can flow freely from one
nucleus to the other. This is the reason
that metals conduct electricity so well ( the
electrons are so free to move.).
Atoms
• Parts of an atom:
– Protons--+charged, relatively mass particles
• Number of protons in an atom determines what
element it is, and is called the atomic number.
– Neutrons– are neutral particles, having no
charge. Similar to protons in size.
• Atoms with the same number of protons but
different numbers of neutrons are isotopes of the
same element.
Atoms
• Parts of an atom continued:
– Electrons-- negatively charged, extremely
light particles 1850 e- make up the mass of
one proton (approximate).
• Behavior of the electrons determines the chemical
behavior of a given element.
Other Atomic Terms Needed
• Ions: An atom without the same number of
electrons and protons resulting in the atom
not being electrically neutral. There are
two types.
– Cations—more protons than electrons, +
charged.
– Anions– more electrons than protons, charged.
Other Atomic Terms Needed
• Electron Shells: electrons orbit the nucleus, but
are restricted to discrete orbital distances from
the nucleus called electron shells.
– Each electron shell can hold a specific number of
electrons (2-8-18-32-32-18-8).
– If a given atom has a full outer elecron shell, that
atom is highly stable and reacts only weakly with
other atoms (Noble gases). All other atoms will either
give away, gain or share electrons.
Mineral Classes
• Based on the dominant chemical
compound that makes up the mineral.
– Silicates—Made of SiO4, in combinations with
various elements such as calcium,
magnesium, iron, etc. The silicates are the
most abundant mineral type in the crust.
• Silicate ions form tetrahedral crystals. These
tetrahedral shapes can form various forms such as
isolated tetrahedra (olivine), rings (cordierite),
single chains (pyroxenes), double chains
(amphiboles), sheets (micas), and frameworks
(quartz).
Mineral Classes
• Carbonates: Made from the carbonate ion
CO3, in combination with various other
elements.
– Calcite is the common carbonate mineral, one
form is aragonite (sea shells). There is also
Calcite (CaCO3), and Dolomite ( CaMgCO3).
• Oxides: Made from oxygen combined with
other elements such as iron, titanium, ect.
Many economically important metals are
mined as oxide ores.
Mineral Classes
• Sulfides: Made of sulfur with other
minerals such as copper, iron, zinc, etc.
Many economically important metals are
mined as sulfide deposits.
• Sulfates: made from the sulfate ion (SO4)
combined with minerals such as clacium,
and barium. Gypsum is a sulfate mineral.
Mineral Classes
• Halides: salts of various kinds. NaCl is
called halite, there are also KCl called
Sylvite.
• Native metals: metals such as Gold, silver,
copper etc..
• Native elements: such as sulfur, diamond,
graphite, arsenic.
Mineral Identification
• To identify minerals we use a variety of physical
properties such as:
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Hardness
Cleavage
Fracture
Luster
Color
Streak
Density
Habit
• You need to know which each of these refer to
and how it is used.
Summary
• You should be able to do the following:
– Define what a mineral is.
– Discuss the Atomic theory of matter (atoms,
protons, neutrons, electrons, etc.)
– Know the types of chemical bonds in minerals
(ionic, covalent, metallic) and how they work.
– Discuss the basics of crystallization (how it
takes place).
– Know the different mineral classes.
– Know how the minerals are identified.
SITES USED
• Thanks to Greg Anderson for use of
lecture notes.
http://pasadena.wr.usgs.gov/office/ganderson/es10/lectures