What is a mineral? "A mineral is a naturally occurring, homogeneous, inorganic, crystalline solid with an orderly internal structure and definable chemical composition"

1
What is a mineral? "A mineral is a naturally
occurring, homogeneous, inorganic, crystalline
solid with an orderly internal structure and
definable chemical composition"
2
05_00.jpg
3
05_02a.jpg
4
Types of bondsIonic bond - exchanged electrons
- example Na and Cl- halite, table salt.
Fairly strong bonds and ionic bonds are the
dominant type of bond in mineralsCovalent bond
- sharing of electrons between ions that do not
readily gain or lose electrons. Example
diamond, all carbon in very strong covalent bonds
in all directions. Most mineral bonds are
combinations of covalent and ionic. ?
5
Bonds between elements form a 3-dimensional
array. If a mineral is allowed to grow without
running into anything, a crystal will form with
flat (planar) surfaces, representing
manifestations of the internal order. Most of
the time, however, minerals run into other
minerals that are crystallizing at the same time,
and the crystal faces do not develop.
6
05_03ab.jpg
7
glass
Crystalline solid
8
05_04and05.jpg
9
05_06.jpg
10
Factors that affect the arrangement of elements
in a mineral are the sizes of the ions involved.
If it is a mineral composed of just one element
(copper, gold, graphite, diamond) or if all ions
are similar in size then the ions all fit
together very nicely.
11
(No Transcript)
12
Graphite or diamond?polymorphs
13
If there are two or more elements in the mineral
formula of different size, then the arrangement
of the ions will be very different. Example
quartz, SiO2 made of silica tetrahedra (but all
oxygens are shared, so formula is SiO2) - 4 large
oxygen ions surround a very small silicon
ion.Or NaCl
14
05_07ab.jpg