ERTH 2001: Classification

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ERTH 2001 Classification

For Wednesdays class Find definitions for
. - mineral - rock - crystal -
gemstone .. and give an example of each
can you name some Earth Materials that are not
any of these things?
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ERTH 2001 Classification

• Classification
• the arrangement of a number of objects, facts,
  ideas, concepts, principles, theories (etc.) into
  related groups
• a fundamental technique for organising
  scientific information into a logical and
  coherent format
• necessary in order to break complex problems,
  materials, ideas, etc. into manageable pieces
• in Earth Materials, an essential first step
  towards identifying minerals, rocks (etc....) and
  towards understanding their origin and
  distribution

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ERTH 2001 Classification
many ways of classifying Earth Materials ....
..... abundance, use, form, value, colour,
distribution ....... minerals are classified
based on chemical composition crystal
structure these determine all the physical,
chemical, and optical properties
which are used to identify minerals
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ERTH 2001 Classification
Chemical Properties
Physical Properties
Minerals
chemical composition crystal structure
Optical Properties
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ERTH 2001 Classification
many ways of classifying Earth Materials ....
..... abundance, use, form, value, colour,
distribution ....... minerals are classified
based on ERTH 2001 chemical
composition crystal structure these determine
all the physical, chemical, and optical
properties which are used to
identify minerals rocks are classified based on
ERTH 2002 mineralogy texture c
hemical composition field relations
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ERTH 2001 Classification

• Classification of Minerals by Chemical
  Composition
• Dana's System of Mineralogy (and its derivatives)
• ca. 15 major groups of minerals with a few
  important subgroups
• - we will see about 10 of these in the lab
• named according to dominant anion or anionic
  group
• basis for organisation of your textbook (Ch.
  12-20) and field guide
• by far the most important group is the
  silicates
• - 6 subgroups based on crystal structure

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ERTH 2001 Classification
CRYSTAL CHEMICAL CLASSES (Dana's System of
Mineralogy) 1. native elements (AFG p.345 Nesse
p.397) 2. sulphides, arsenides, tellurides (AFG
p.357 Nesse p.378) 3. sulphosalts (AFG p.383
4. simple oxides (AFG p.393 Nesse p.356) 5.
hydroxides (AFG p.407 Nesse p.370) 6. multiple
oxides (AFG p.415 Nesse p.363, 367) 7. halides
(AFG p.425 Nesse p.374) 8. carbonates (AFG
p.431 Nesse p.326) 9. borates (AFG p.447 Nesse
p.353) 10. sulphates (AFG p.453 Nesse
p.340) 11. chromates (AFG p.469) 12. phosphates,
arsenates, vanadates (AFG p.471 Nesse
p.347) 13. vanadium oxysalts (AFG p.493) 14.
molybdates, tungstates (AFG p.495 Nesse
p.352) 15. silicates 6 different subclasses
based on crystal structure we will look at at
least one example of each of these in Labs HS-1-5
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ERTH 2001 Classification

• Classification of Minerals by Chemical
  Composition
• Dana's System of Mineralogy (and its derivatives)
• ca. 15 major groups of minerals with a few
  important subgroups
• - we will see about 10 of these in the lab
• named according to dominant anion or anionic
  group
• basis for organisation of your textbook (Ch.
  12-20) and field guide
• by far the most important group is the
  silicates
• - 6 subgroups based on crystal structure
• before tackling this system, you need to know
  the basics of
• Crystal Chemistry (Nesse, Ch. 3)
• Crystal Structure (Nesse, Ch. 4)
• crystallography (Nesse, Ch. 2) will be
  dealt with a little later

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ERTH 2001 Classification
 SOME TERMS THAT CAN CAUSE CONFUSION Crystal
chemical class (Dana) Classification of minerals
based on chemical composition (crystal structure
is irrelevant). There are ca. 15 main categories,
with the "silicate" class further subdivided into
6 subclasses. The mineral descriptions in Nesse
and AFG are arranged by crystal chemical
class. Crystal system Classification based on
symmetry of crystal structure (composition is
irrelevant). There are 6 (or 7) crystal systems,
with subdivisions of each (space groups and point
groups not discussed in detail in this class)
based on specific symmetry elements. Details
will be dealt with in the labs (see Lab Manual,
p. 4-6)
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ERTH 2001 Crystal Chemistry (Nesse, Ch. 3)

• Nature of Chemical Elements (p.39-45)
• Abundance of Elements (p.45-46)
• Chemical Bonding (p.46-52)
• Sizes of Atoms and Ions (p.53-55)

some knowledge of basic chemistry will be
assumed focus here is on aspects relevant to
minerals for help, see www.chemtutor.com (or
similar site)