The Importance of Mineralogy and Mineral Identification
Skills
Slide 2
Importance of Mineralogy List 5 things in this classroom that
you think were mined?
Slide 3
Importance of Mineralogy Almost everything except things that
were grown (made from wood). Some surprising things that are mined:
1) Plastics all made from oil 2) Your clothing - half cotton
(grown), half polymers or plastics (nylon, dacron, rayon, spandex -
polymers made from petroleum). 3) Even the carpets and the drapes
are made from polymer plastics. 4) Most cosmetics polymers. 5) The
lead in your pencils actually Graphite 6) Salt yes, you are eating
rocks! 7) Glass made from sand. 8) 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.
Slide 4
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.) The mineral ores of copper All METAL
resources come from mineral ores. Most of these metals come from
impure forms sulfides, oxides, sulfates, carbonates, silicates,
etc
Slide 5
Importance of Mineralogy Hence the knowledge of minerals, their
geological occurrence and their identification is the key to one of
Canadas largest industries. The overall value of production of the
Canadian mining, mineral- processing, 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.
Slide 6
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.
Slide 7
Importance of Mineralogy In short, this data basically tells us
that a degree in the Earth Sciences is the key to one of Canadas
fastest growing, most well paid industries! Right now there are
more jobs in the mining industry than Canadians with suitable
qualifications. Excerpt from the Mining Association of Canada to
the Competition Policy Review Panel (2006)
Slide 8
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
Slide 9
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
Slide 10
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.
Slide 11
Mineral identification Labs A minerals 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 minerals crystal form is directly related
to its atomic arrangement. Chemicals properties (such as reaction
to acids) are directly related to a minerals chemical
composition.
Slide 12
Mineral Identification Tests Sight tests: 1) Colour 2) Crystal
Form 3) Cleavage and Fracture 4) Lustre Physical Tests: 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
Slide 13
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! 5 colours of the mineral Quartz
Slide 14
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
Slide 15
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.
Slide 16
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
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 with
many cleavage planes tend to sparkle. blocky cleavage of feldspar
perfect basal cleavage of mica
Slide 17
Common types of Cleavage
Slide 18
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
Slide 19
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!
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!
Slide 22
Mohs Hardness Scale 1) Talc 2) 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 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.
Slide 23
Mohs Hardness Scale The relation between the Moh's Scale and
absolute hardness measured by other means is shown below:
Slide 24
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
Slide 25
6) Specific Gravity (SG) or Density Description Density in g/cm
3 (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)
Slide 26
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 sub- metallic 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.
Slide 27
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
Slide 28
9) Reaction to Acid Description Reaction of hydrochloric acid
with carbonates particularly calcium carbonate (CaCO 3 ). 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!
Slide 29
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. 5 colours of the
mineral Quartz 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.
Slide 30
Mineral Collection 1Quartz11Barite*21Galena
2Pyroxene*12Gypsum22Chalcopyrite 3Amphibole13Apatite*23Pyrrhotite *
4Talc14Calcite24Bornite* 5Biotite15Garnet25Graphite
6Muscovite16Hematite26Fluorite 7Phlogopite*17Magnetite27Halite
8Orthoclase18Corundum*28Malachite
9Plagioclase19Sphalerite29Chromite* 10Olivine*20Pyrite30Sodalite* *
Do no teach these minerals if time is limited
Slide 31
Silicates mineralformulamineralformula Quartz (1) SiO 2
(framework silicate) Orthoclase (8) (Feldspar) (3-D framework
structure) KAlSi 3 O 8 Pyroxene (2) CaMgSi 2 O 6 (single chain
silicate) Plagioclase (9) (Feldspar) (3-D framework structure) CaAl
2 Si 2 O 8 Amphibole (3) A 2 Z 5 Si 8 O 22 (OH) 2 or (double chain
silicate) Olivine (10) (isolated silicon tetrahedrons) (Mg,Fe) 2
SiO 4 Talc (4) Mg 3 Si 4 O 10 (OH) 2 (sheet silicate) Garnet (15)
(ring structure) A 3 Z 2 Si 3 O 12 Biotite (5) mafic mica (sheet
silicate) Sodalite (30) Feldpathoid feldspar like structure Na 8 Al
6 Si 6 O 24 Cl 2 Muscovite (6) felsic mica (sheet silicate)
Phlogopite (7) intemediate mica (sheet silicate)