Notes 3 minerals:
The principal characteristics of a mineral are:
1.element or compound
2.
natural 3. inorganic 4. solid 5. definite chemical structure
Minerals are:
Elements or compounds found in nature.
If a mineral is an element
It is composed entirely of that one substance
If a mineral is an compound
It follows the “Law of definite proportions”
Either way a mineral always has:
A Characteristic Chemical Composition.
Crystalline structure
The regular arrangement of ions that results in
regular geometric-forms
Example: Quartz
Has a ratio of one atom of silica to 4 atoms of
oxygen
Definition of a Rock: It is made of one or more
minerals.
The slower the cooling of
molten rock, the larger the crystals
Silicate minerals are: Compounds that contain the two elements:
Silica and Oxygen
The Silica Tetrahedron: The basic building block of most of the earth’s crust
The native minerals that are
different forms of carbon are: Graphite and Diamond
The main rock type in oceanic
plates is Basalt
The main rock type in
continental plates is Granite
The two main elements in the lithosphere are: Silica
and oxygen
Geologists have identified:
Over 2000 minerals
Only 10 of these make
up the bulk of the rocks.
Ores: Rocks from which minerals of economic value are
extracted
Minerals
2 Powerpoint
Mineral Physical Properties: Luster Color Hardness
Cleavage Streak Specific Gravity
Luster
is the appearance of a
fresh mineral surface in reflected light and include: Metallic
Luster, and Non-Metallic Luster (or Glassy
Luster and Earthy Luster (kaolinite))
Hardness
is the mineral’s resistance to scratching.
It can be determined by trying to scratch a mineral of
unknown hardness with a substance of known hardness
Hardness is measured on a relative scale called the
Mohs Scale of Hardness which consists of ten common minerals arranged in order
of their increasing hardness.
You must know by heart the hardness of: fingernail (2),
copper penny (3.5),
glass plate (5.5), steel file (6).
Cleavage:
is the way a mineral
breaks. Minerals that break along smooth, flat surfaces have cleavage. Mica has
cleavage
Fracture: The
way a mineral breaks.
Quartz has Conchoidal
fracture Fibrous fracture
Streak: is the color of a mineral’s powder. The streak is determined by
rubbing the hand specimen on a piece of unglazed porcelain (streak plate). The streak of a mineral may or may not be the same as
the color of the hand specimen.
Specific Gravity: is the weight per unit volume, and is
a dimensionless number. It represents the ration of the mineral’s weight to
the weight of an equal volume of water.
Crystal Form: The way a mineral grows. Represents the
outer growth surfaces.
Slow cooling allows fewer (larger) crystals = coarse
texture to rock
Rapid cooling leads to many small crystals = smooth
texture to rock
List
three Special Properties of Minerals:
magnetism,
Magnetite
taste,
Halite (table salt)
odor,
Sulfur (rotten eggs)
chemical reaction with acid, Calcite ( w/ HCl)
What are the major mineral groups, significance, and
examples of minerals in each?
Silicates: most of crust & mantle. metal + silicon
& oxygen. grouped based on structure. major difference:
Si/O ratio
Common Silicate Minerals: Quartz: The 2nd most abundant mineral.
Feldspar: The most abundant mineral.
Oxides: metal +
oxygen Ores Magnetite
Sulfides: metal +
sulfur ores
Sulfates: metal +
sulfur +oxygen Gypsum
Halides: salts formed from evaporation of seawater Halite
Native
Elements Minerals which
occur free or uncombined in the rock are said to be native.
Examples: Native
Gold, silver, copper, molybdenum.
ORES:
The metal zinc is extracted from the mineral:
Sphalerite:
The metal tin is extracted from the mineral:
Cassiterite
Ore
of iron Hematite
The metal lead is extracted from the mineral
Galena
The metal Aluminum is extracted from the mineral Bauxite
The metal Copper is extracted from these minerals
Azurite, malachite and chalcopyrite
Carbonates: metal
+ carbon & oxygen. Seashells. Calcite.
Calcite: The mineral that makes up limestone
Limestone is a commonly occurring rock which can
be used not only for building, but also for making many other useful materials
including Lime, Cement and Glass. It is also added to Bread and Toothpaste.
Limestone is a sedimentary rock, formed from the
bones and shells of sea creatures living millions of yeas ago.
Limestone is mainly a chemical compound called
Calcium Carbonate
CaCO3
Carbonates generally can neutralise acids, so
powdered limestone may be used without any more processing, to neutralise the
acidity of lakes and soil
Limestone heated in a Kiln undergoes Thermal
Decomposition to form Quicklime Calcium Oxide CaO
Quicklime is a very strong alkali, which reacts
with water to produce Slaked Lime Calcium Hydroxide Ca(OH)2
(Lime water), this is also an alkali used to reduce acidity in soil.
Cement is produced by heating powdered limestone
and clay, in a Rotary Kiln.
There are many different types of glass, each
with its own properties and uses, but essentially, Glass is made by heating
together a mixture of:
Powered limestone, sand and soda.
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