The Importance of Mineralogy
and Mineral Identification Skills
Importance of Mineralogy
List 5 things in this
classroom that you
think were mined?
Importance of Mineralogy
Almost everything except things that were grown (made
from wood). Some surprising things that are mined:
1)
2)
3)
4)
5)
6)
7)
8)
Plastics – all made from oil
Your clothing - half cotton (grown), half polymers or plastics (nylon,
dacron, rayon, spandex - polymers made from petroleum).
Even the carpets and the drapes are made from polymer plastics.
Most cosmetics – polymers.
The lead in your pencils – actually Graphite
Salt – yes, you are eating rocks!
Glass – made from sand.
The chalkboard and the chalk. Chalk is made from pure limestone which
is made from the skeletons of tiny ocean plankton.
 Let your English teacher know of the cruelty of smearing the skeletons of dead
animals across the chalkboard every time chalk is used.
Importance of Mineralogy
 The three most economically important groups of mineral
resources are:
1) Fossil fuels (oil, coal and gas)
2) Aggregates (gravel, sand and cement)
3) Metal resources (iron, copper, gold, etc.)
All METAL resources come from mineral ores. Most of these
metals come from impure forms – sulfides, oxides,
sulfates, carbonates, silicates, etc…
The mineral ores of copper
Importance of Mineralogy
 Hence the knowledge of minerals, their geological
occurrence and their identification is the key to one
of Canada’s largest industries. The overall value of
production of the Canadian mining, mineralprocessing, and metal producing industries totals
approximately $42 billion per year.
 Canada is now one of the largest mining nations in the
world, producing more than 60 minerals and metals.
The mining industry is a major player in Canada's
economy and contributes nearly 5% of the country's
Gross Domestic Product. Mining in Canada also
accounts for 19% of the country's total exports.
Importance of Mineralogy
The mining industry provides Canadians with career
opportunities. In 2007, the mining and mining processing
industries directly employed 363,000 Canadians. And more
skilled workers are needed. Current estimates indicate that
the mining industry will need thousands of additional
workers each year up to the year 2016!
Canada ranks first in the world for the production of
potash and uranium, and ranks in the top five for the
production of nickel, cobalt, titanium concentrate,
aluminum, magnesium and platinum group metals, gypsum,
asbestos, cadmium, zinc, salt, molybdenum, and diamonds.
Importance of Mineralogy
Excerpt from the Mining Association of Canada to the Competition Policy Review Panel (2006)
In short, this data basically tells us that a degree in the Earth
Sciences is the key to one of Canada’s fastest growing, most
well paid industries! Right now there are more jobs in the
mining industry than Canadians with suitable qualifications.
Exploration Geology
 Since a vast array of products are
produced from minerals, it is
important that a geologist can
identify one mineral from another.
 Today, I will introduce basic mineral
identification skills and introduce the
first few minerals from our mineral sets
 Next class, we will define what a mineral
is and discuss mineral chemistry and
crystal structure.
Realgar (AsS)
Gold nugget
Mineral Sets and Testing Equipment
1) Take out the mineral sets and mineral test kits.
2) There are 30 minerals that you will need to know
how to identify.
3) These minerals are chosen because they are either
common or economically important.
4) There are over 3000 naturally occurring minerals but
an average geologist might know how to identify 50
to 100 minerals. A mineralogy specialist might know
a few hundred.
5) The first step in mineralogy is to know how to
conduct the basic identification tests
Mineral identification Labs
 In this course you will be expected to know how to identify
about 30 common minerals and to know their chemical
formulas.
 In order to identify these minerals, you will learn to use
about 10 mineral identification tests.
 For each mineral that you learn in the lab, you will be given
the data for some of the tests and will be conducting the
tests to obtain some data for yourselves.
 When identifying minerals in the field or in the lab, it is
only necessary to know two or three key pieces of
information to make a positive identification.
Mineral identification Labs
 A mineral’s physical properties are a result of their internal





chemical structure.
Silicate minerals tend to be hard because they have mostly
covalent bonds and few ionic bonds.
Similarly some minerals like Talc or Graphite are soft due to weak
Van der Waals bonds.
Many minerals have a high density due to a prevalence of heavy
atoms. For example, Galena is very dense due to Pb atoms.
A mineral’s crystal form is directly related to its atomic
arrangement.
Chemicals properties (such as reaction to acids) are directly
related to a mineral’s chemical composition.
Mineral Identification Tests
Sight tests:
1)
2)
3)
4)
Physical Tests:
Colour
Crystal Form
Cleavage and Fracture
Lustre
1) Hardness
2) Specific Gravity
(Density)
3) Streak
4) Magnetism
5) Reaction to Acid
Other tests such as taste, fluorescence
and radioactivity are used in rare cases
to identify some minerals.
Mineral test equipment
1) Colour
Description
The colour of minerals depends on the presence of certain atoms.
Quartz can gain any colour due to chemical impurities.
Testing method
1)
Look at the sample and determine its colour - white,
black, green, clear, etc.
2) COLOUR can be deceiving – impurities in the mineral
can change the colour of ANY mineral. As you can see
below, quartz can be just about any colour!
2) Crystal Form
Description
Geometric shape of a crystal or mineral.
Testing method
1) Examine and describe the geometric
shape of the mineral - cubic,
hexagonal, etc.
2) Not all minerals display crystal form
commonly – in fact, crystal habit is
rarely seen in most of the common
rock forming minerals.
3) MASSIVE – the term used to
describe minerals that do not display
crystal form
The 6 Crystal Classes
The shape of crystals is based on the internal
symmetry of the crystals. All mineral crystals fall into
one of these 6 or 7 classes. Examples of minerals and
the crystal classes they belong to can be seen in the
chart at right.
3) Cleavage
Description
Breakage of a mineral along planes of weakness in the crystal
structure. Cleavage is related to the crystal class of a
mineral.
Testing method
1) Examine the mineral for areas where the
mineral is broken. Look for areas where the
blocky cleavage of feldspar
light reflects from planar surfaces.
2) This can be easily confused with a crystal
face and is the most difficult properties for
students to master.
3) Not all minerals show cleavage. Minerals perfect basal cleavage of mica
with many cleavage planes tend to sparkle.
Common types of Cleavage
Fracture
Description
Breakage of a mineral, not along planes of weakness in the
crystal structure.
Testing method
1) Examine the mineral for
areas where the mineral is
broken.
2) Describe the breakage as
either irregular or
conchoidal (has the
appearance of broken glass)
The conchoidal fracture of quartz
4) Lustre
Description
Character of the light reflected by a mineral. It is a measure
of how “shiny” a mineral is.
Testing method
1) Look at the sample to determine if the mineral is:
metallic – lustrous, looks like a metal
non-metallic – non-lustrous, dull, earthy
sub-metallic – displays a somewhat metallic
appearance but tends to be duller.
2) Metallic minerals tend to be sulfides while sub-metallic
minerals are generally oxides and some sulfides
3) Mineral books will list a wide variety of lustre terms that
we do not need to know!
Lustre
Metallic
Pyrite
Galena
Sub-Metallic
Sphalerite
Hematite
Non-Metallic
Talc
Feldspar
5) Hardness
Description
Resistance to scratching or abrasion. Put in other terms – the
ability of one mineral (or material) to scratch another.
Testing method
1) Rate hardness based on the Mohs Hardness Scale.
2) Use your hardness testing kits to rate minerals as:
very soft – can be scratched with fingernail
soft - too hard to scratch with fingernail but can be
scratched easily with a nail.
hard – difficult to scratch with nail but cannot scratch glass
very hard – scratches glass
3) Only leave a scratch of 2 or 3 mm in length on a mineral!
Moh’s Hardness Scale
Talc
Gypsum
fingernail = 2.5
3) Calcite
old copper penny = 3.5
4) Fluorite
5) Apatite
6) Orthoclase (Feldspar)
window glass or
typical knife blade
= 5.5 to 6.0
7) Quartz
8) Topaz
9) Corundum
(Ruby/Sapphire)
10) Diamond
1)
2)
 The Mohs Hardness Scale is only
relative. Meaning that fluorite at
4 is not twice as hard as gypsum
at 2; nor is the difference
between calcite and fluorite
similar to the difference between
corundum and diamond. An
absolute hardness scale looks a
little different than the relative
scale.
 One word of caution for
inexperienced collectors: do not
SCRATCH NICE CRYSTAL
FACES! A fractured, cleaved or
inconspicuous part of the
mineral should still give a good
hardness test and not damage a
potentially wonderful specimen.
Moh’s Hardness Scale
 The relation between the
Moh's Scale and absolute
hardness measured by other
means is shown below:
Hardness Scale Equipment
 Mineral Testing Kits
will include a nail and
glass plate for
hardness testing.
 Place the glass plate on
the table when testing
hard minerals or else it
may shatter in your
hand!
 A 2-3 mm scratch is
enough when using a
pen knife/nail
Fingernails have a hardness of 2.5.
Any mineral that can be scratched by
a fingernail is VERY SOFT
If a mineral cannot be
scratched by your fingernail
but can be scratched by a
knife or nail (5.5) it is SOFT
If a mineral cannot be
scratched by a knife/nail but
cannot scratch a glass plate
(5.5) it is HARD
Any mineral that can scratch a glass
plate is VERY HARD
6) Specific Gravity (SG) or Density
Description
Density in g/cm3 (water = 1). Ratio of the mass of a mineral to the
mass of an equal volume of water. It is measure of how “heavy”
a mineral is for its given volume.
Testing method
1) Qualitative descriptions are generally used:
light – S.G. is less than 2.5
medium – S.G. is between 2.5 and 3.5
heavy – S.G. is between 3.5 and 5.0
very heavy – S.G. is greater than 5.0
2) All metallic minerals are heavy so use comparative terms
(example – heavy for a non-metallic mineral)
7) Streak
Description
Colour of the mineral when it is powdered. The colour
produced when the mineral is scraped (streaked) across an
unglazed porcelain tile.
Testing method
1) Use this test only on metallic and submetallic minerals.
2) Grind a small amount of a mineral into a
powder on a porcelain streak plate and
determine the colour of the powder.
3) Unlike the hardness test, a larger more
forceful test is OK.
4) Make sure you are streaking the correct
mineral.
8) Magnetism
Description
The electromagnetic force generated by a mineral
Testing method
1)
Use the magnet supplied in the
Mineral Testing Kit and determine
if a magnet is attracted to the
sample.
2) Few minerals are magnetic
(examples – magnetite, pyrrhotite)
and they tend to iron-bearing
metallic minerals.
Magnetite (Fe3O4) – also
known as lodestone
9) Reaction to Acid
Description
Reaction of hydrochloric acid with carbonates – particularly
calcium carbonate (CaCO3).
Testing method
1)
Using the acid dropper bottles
supplied in the Mineral Testing
Kits, place one small drop of HCl
on a sample a watch for a reaction
- effervescence (bubbles).
2) Wipe the sample with a tissue
after the test.
3) Though the acid is relatively
weak, use acid carefully!
10) Other tests
Taste
This test is only useful when determining the presence of
halite (NaCl) or potash (potassium salts).
This test is not recommended for any other minerals due to
the presence of toxic compounds, especially heavy metals.
Radioactivity
This test is conducted with a Geiger counter and is useful in
identifying radioactive minerals such as Uraninite or
Pitchblende (UO2)
Fluorescence
Some minerals fluoresce under ultraviolet (shortwave UVB)
radiation. Minerals such as Scheelite (CaWO4) and diamond.
Mineral Collection
1
Quartz
11
Barite*
21
Galena
2
Pyroxene*
12
Gypsum
22
Chalcopyrite
3
Amphibole
13
Apatite*
23
Pyrrhotite *
4
Talc
14
Calcite
24
Bornite*
5
Biotite
15
Garnet
25
Graphite
6
Muscovite
16
Hematite
26
Fluorite
7
Phlogopite*
17
Magnetite
27
Halite
8
Orthoclase
18
Corundum*
28
Malachite
9
Plagioclase
19
Sphalerite
29
Chromite*
10
Olivine*
20
Pyrite
30
Sodalite*
* Do no teach these minerals if time is limited
Silicates
mineral
formula
mineral
formula
Quartz
(1)
SiO2
Orthoclase (8)
(Feldspar)
KAlSi3O8
(framework silicate)
(3-D framework structure)
Pyroxene
(2)
CaMgSi2O6
(single chain silicate)
Plagioclase (9)
(Feldspar)
CaAl2Si2O8
(3-D framework structure)
Amphibole
(3)
A2Z5Si8O22(OH)2 or
Olivine (10)
(double chain silicate)
(isolated silicon
tetrahedrons)
Talc
(4)
Mg3Si4O10(OH)2
(sheet silicate)
Garnet (15)
(ring structure)
Biotite
(5)
mafic mica
Sodalite (30)
(sheet silicate)
Feldpathoid – feldspar like
structure
Muscovite
(6)
Phlogopite
(7)
felsic mica
(sheet silicate)
intemediate mica
(sheet silicate)
(Mg,Fe)2SiO4
A3Z2Si3O12
Na8Al6Si6O24Cl2