Transcript What is a Mineral?

Minerals Objectives
•List 5 characteristics all minerals share
•Give examples of 2 ways that minerals form
•List the physical properties to identify minerals
•Describe how physical properties are used to identify
minerals
•List characteristics that gems have that make them
different from and more valuable than minerals
•List the conditions necessary for a mineral to be
classified an ore
•List the properties of titanium that make it useful in
biomedicine
•Identify the minerals that are mined for titanium
What is a Mineral?
• A mineral is
a naturally occurring,
inorganic solid
with crystalline form
and definite chemical composition.
The Structure of Minerals
• Crystals – a solid in which the atoms are
arranged in repeating patterns: Go to Pg. 63 and
draw each sample by their pattern name. Due
Thursday at the beginning of class.
• 1. Cubic
• 2. Tetragonal
• 3. Hexagonal
• 4. Orthorhombic
• 5. Monoclinic
• 6. Triclinic
Mineral Formation
1. Magma formation- cooling of hot molten rock material
-Atoms lose energy and move closer together, patterns.
2. Liquid evaporation- minerals dissolved in liquids
-Liquid evaporates atoms of minerals stay & form crystals
3. Precipitation- alternate material in supersaturated
solutions
Mineral Identification
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5.
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Color
2. Luster
Streak
4. Hardness
Cleavage
6. Fracture
Crystal form
8. Density
Specific gravity 10. Magnetism
Reaction to hydrochloric acid (HCl)
Taste
Fluorescence
Double refraction
1.Color
not always diagnostic (feldspar, quartz, fluorite)
Feldspar can be green, pink white, gray, etc.
2. Luster
Metallic, non-metallic
glassy or vitreous, dull, pearly,
resinous, waxy, adamantine, silky
3. Streak
Using a unglazed porcelain plate
scratch the porcelain and note
color, odor if any.
1.Both of these samples are hematite; both have a
reddish-brown streak
4. Hardness
Moh’s Scale of Hardness (1-10)
1.Talc
2.Gypsum ____ fingernail
3.Calcite ___ penny (copper)
4.Fluorite ___ iron nail
5.Apatite ___ glass
6. Orthoclasefeldspar(Kfeldspar)
7. Quartz
8. Topaz.
9. Corundum
10. Diamond
Minerals Objectives
•List 5 characteristics all minerals share
•Give examples of 2 ways that minerals form
•List the physical properties to identify minerals
•Describe how physical properties are used to identify
minerals
•List characteristics that gems have that make them
different from and more valuable than minerals
•List the conditions necessary for a mineral to be
classified an ore
•List the properties of titanium that make it useful in
biomedicine
•Identify the minerals that are mined for titanium
5. Cleavage
Breakage along planes. Related to crystal structure
1 direction
(muscovite, biotite)
Muscovite (left) Biotite (right)
2 directions at 90°
(feldspar, pyroxene)
Pyroxene
3 directions at 90° (cubic)
(halite, galena)
Halite
Galena
3 directions not at 90°(rhombohedral)
(calcite, dolomite)
Cleavage fragments of calcite
Cleavage fragments of dolomite
4 directions (octahedral)
6 directions
(fluorite)
(sphalerite)
Cleavage fragments of fluorite
Sphalerite
6. Fracture
irregular breakage (no cleavage), breakage
not along smooth planes
Conchoidal fracture
smooth curved fracture surfaces
occurs in quartz, chert, obsidian, glass
Rose quartz and obsidian lacks cleavage;
they have conchoidal fracture
7. Crystal form
Some minerals that may or may not have cleavage GROW (not
break) into crystals with flat sides.
quartz
pyrite
Quartz crystals
Physical Properties cont.
8. Density : D=mass/volume
9. Specific gravity (similar to density) Weight of
a mineral divided by weight of an equal
volume of water.
10. Magnetism: Can be picked up by a magnet
or may be a natural magnet.
11. Reaction to hydrochloric acid (HCl)
Calcite effervesces in acid.
12. Taste : halite, sylvite
13. Fluorescence: Some minerals glow in the
dark under a black light (U.V. light) Due to
excitation of electrons
14.Double refraction
Light passing through the mineral is split into two rays. Causes an optical
"doubling" effect.
Calcite
Calcite has the optical property of double refraction. In the photos above, the
same sample of calcite is used. It is rotated over a thin dark line. Examine how
the appearance of he line changes in the different orientations of calcite.
Mineral Composition and Groups
• 90 elements occur naturally in Earth’s crust.
• 98% of the crust is made of only 8 elements
46.6% Oxygen, 27.7% Silicon, 8.1% Aluminum, 5% Iron,
3.6% Calcium, 2.8% Sodium, 2.6% Potassium, 2.1%
Magnesium, 1.5% others
• 4000+ known minerals, a few dozen are
common and these are composed of the 8
common elements
Minerals Objectives
•List 5 characteristics all minerals share
•Give examples of 2 ways that minerals form
•List the physical properties to identify minerals
•Describe how physical properties are used to identify
minerals
•List characteristics that gems have that make them
different from and more valuable than minerals
•List the conditions necessary for a mineral to be
classified an ore
•List the properties of titanium that make it useful in
biomedicine
•Identify the minerals that are mined for titanium
Major Mineral Groups
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Silicates – SiO2 – silicon, oxygen + element
Carbonates – CO3
Oxides – element + Oxygen (O2)
Sulfides – element + sulfur (S)
Sulfates- SO4
Halides – Salts with( +) or( –) ions
Hydroxides- OH
Phosphates – PO4
Native elements – single elements ( Au, Ag, Cu)
Uses of Minerals
• Gems: have crystal structure which allows them
to be cut and polished
• Rare and beautiful
• Brighter and more colorful
Ex: Opal
More Gemstones
Azurite and
Malachite
Ores: are minerals which contain a useful substance which
can be mined for a profit.
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Bauxite – Aluminum
Hematite – Iron
Sphalerite – Zinc
Chalcopyrite - Copper
Zinc:
Sphalerite
Copper:
For coins, wire
Chalcopyrite
Ores continued:
Waste Rock Removal- Cost –vs- demand:
In order to get the ore waste material must be removed first. This
may be costly both on the $ end and to the environment. If the cost
of the removing of the waste gets higher than the value of the desired
material, then it is no longer considered an ore.
Technology and Minerals
Rutile: produces Titanium which is lightweight, durable, and
nontoxic. Used in bicycles, airplanes, hip replacements. Most
titanium is mined from rutile rather than ilmenite because the
mining and processing from ilmenite is hazardous to the
environment.
Minerals as Paint Pigments
Many minerals used as pigments were poisonous
Lead, arsenic, mercury. Cinnabar – red (mercury)
Greens and blues: malachite and azurite.
Dark blue ultramarine: lapis lazuli
Ochre: yellow clay containing iron.
White: from compounds containing; calcium, zinc, titanium
and lead.