Chapter 3,Atoms,Elements,Minerals,
Rocks,Earth’s Building Materials
? Mineral
? Naturally formed,inorganic,solid material with a
specific chemical composition and a characteristic
crystalline structure.
? Rock
Naturally formed,coherent mass of one or more
minerals,sometimes including organic debris.
Introduction, What Is A Mineral?
Key Characteristics of Minerals
? Minerals have two key characteristics.
? Composition:
? The chemical elements that compose a mineral,
and their proportions.
? Crystal structure:
? The organized way in which the atoms of the
elements are packed together in a mineral.
Composition of Minerals
? A few minerals are composed of a single
element (diamond,graphite,gold,copper,
and sulfur).
? Most minerals are compounds,containing
more than one element.
? Chemical elements are the most
fundamental substances into which matter
can be separated by chemical means,
Crystal Structure of Minerals
? The atoms in most solids are organized in
regular,geometric patterns,called the crystal
structure.
? Solids that have a crystal structure are said to
be crystalline.
? Ice in a glacier meets the definition of a mineral.
? Solids that lack crystal structures are amorphous.
? glass and amber.
Crystal Form
? Crystal,any solid body that grows
with planar surfaces.
? The interfacial angle in any crystalline
structure remains constant.
Iregular Growth of Quartz grains
Fibers of Chrysotile Asbestos
Growth Habit and Polymorphism
? Growth habit:
? The characteristic crystal form of each mineral.
? Polymorphism:
? Some elements and compounds form two or
more different minerals:
? C Graphite,Diamond
? CaCO3 Calcite,Aragonite
? FeS2 Pyrite,Marcasite 白铁矿
? SiO2 Quartz,Cristobalite 方英石
Cleavage
? Cleavage is the tendency to break in preferred
directions along bright,reflective planar surfaces.
? A cleavage surface is a breakage surface,
whereas a crystal face is a growth surface.
? The planar directions along which cleavage
occurs are governed by the crystal structure.
? They are planes along which the bonding between
atoms is relatively weak.
Mineral cleavage--Halite three
well defined cleavage
Luster
? Luster is the quality and intensity of light
reflected from a mineral.
? The most important lusters are:
? Metallic (polished metal surface).
? Vitreous (glass).
? Resinous (resin),the look of dried glue or amber.
? Pearly (pearl),the iridescent闪广的 look of a pearl.
? Greasy (as if the surface were covered by a film of
oil),
Quartz has a vitreous luster
Sphalerite 闪锌矿 has a resinous luster
Talc has a pearly luster
Color and Streak
? Color is determined by several factors,but its
main cause is chemical composition.
? Unreliable for identification.
? Streak is the thin layer of powdered material
left when a specimen is rubbed on an unglazed
ceramic plate,
? Much more reliable than color for identification.
Hardness and the Mohs Scale
? Hardness is a mineral’s relative
resistance to scratching.
? The Mohs relative hardness scale uses ten
minerals,each with its distinctive
hardness:
? scale indicate relative hardness.
? 10.diamond
? 9.Corundum
? 8.Topaz
? 7.Quartz
? 6.Potassium feldspar Pocket knife and glass
? 5.Apatite
? 4.Fluorite Copper penny
? 3.Calcite fingernail
? 2.Gypsum
? 1.Talc
Mohs relative hardness scale
Density and Specific Gravity
? Density is mass per unit volume.
? Minerals with a high density,such as
gold,contain atoms with high mass
numbers that are closely packed.
? Minerals with a low density,such as ice
have loosely packed atoms.
? The unit of density is gram per cubic
centimeter (g/cm3).
Specific Gravity
? Density is easily measured using the
property called specific gravity.
? Specific gravity is the weight of a
substance in air divided by the weight of
an equal volume of pure water.
? Specific gravity is a ratio of weight.
Common Minerals in Earth’s Crust
? Only 12 elements occur in the continental crust
in amounts greater than 0.1 percent by weight.
? These 12 elements make up 99.23 percent of the
crustal mass.
? The crust,therefore,is constructed mostly of a
limited number of minerals.
? Approximately 4,000 minerals have been
identified,but only about 30 are commonly
encountered.
Average composition of the continental crust
Three Mineral Groups
? Silicate minerals (SiO4)4-,the most
abundant in Earth’s crust.
? Carbonate (CO3)2-,phosphate (PO4)3-,
and sulfate (SO4)2- minerals.
? Ore minerals,sulfides (S2-) and oxides
(O2-) that contain valuable metals.
Silicates,The Largest Mineral Group
? Two elements,oxygen and silicon,make up
more than 70 percent of the weight of the
continental crust.
? Polymerization 集合 is the creation of
compounds by accepting or sharing
electrons,
? Linking silicate tetrahedra by oxygen
sharing results in huge anions.
? It produces endless chains.
Silicate Tetrahedron
Olivines and Garnets
? Two very important rock-forming mineral
groups,the olivines and the garnets,have
crystal structures in which the silicate
tetrahedra are isolated.
? Olivine is among Earth’s most abundant
mineral groups,a very common constituent of
igneous rocks in oceanic crust and the upper
part of the mantle.
olivine
Olivines and Garnets (2)
? Olivine occurs in such flawless and
beautiful crystals that is used as a gem,
peridot,
Chains,Pyroxenes and Amphiboles
? One of the most important mineral groups,the
pyroxenes,contains single-chain linkages.
? The most common pyroxene is called augite.
? A very common and important family of
minerals,the amphiboles,contains double
chains.
? The most common of the amphiboles is called
hornblende.
Large Anions formed by polymerization
Chains,Pyroxenes and Amphiboles
? The pyroxenes and the amphiboles are
hard to tell apart.
? The cleavages in pyroxene are right
angles (90o).
? The cleavages in amphibole are at 120o.
Cleavage in the chain silicates
Common silicate minerals
Sheets,Clays,Micas,Chlorites,and
Serpentines
? Kaolinite,Al4Si4O10(OH)8,is one of the
most common clays.
? Muscovite,KAl2(Si3Al)O10(OH)2,is a
common mica.
? Chlorite,which contains Mg2+ and Fe2+
cations,is usually greenish in color.
Crystals of the clay mineral Kaolinite
Sheets,Clays,Micas,Chlorites,and
Serpentines (2)
? The serpentine group consists of three
polymorphs with the formula
Mg6Si4O10(OH)8.
? Chrysotile 温石棉 is the white asbestos of
commerce,
Quartz
? Quartz is pure SiO2.
? Forms six-sided crystals.
? Found in many colors.
? The colors come from minute amounts of iron,
aluminum,titanium,and other elements
present by ionic substitution.
? Fine grain forms of quartz are called
chalcedony玉髓,
? Agate 玛瑙
? Flint 燧石 (gray)
? Jasper 碧玉 (red)
The colors of Quartz
The Feldspar Group — Most Common
Minerals in Earth’s Crust
? The most common mineral group in Earth’s
crust.
? Accounts for about 60 percent of all minerals
in the continental crust.
? Feldspar and quartz constitute 75 percent of
the volume of the continental crust.
? Feldspar has a structure formed by
polymerization.
Green feldspar/amazonite
The Carbonates Group
? The carbonate anion,(CO3)2-,forms
three common minerals:
? Calcite
? Aragonite
? Dolomite
? Calcite reacts vigorously to HCl.
Calcite and dolomite are differ with fizz and effervesce
The Phosphate and Sulfate Mineral Groups
? Apatite is the most important
phosphate mineral.
? Contains the complex anion ((PO4)3-.
? Common mineral in many varieties of
igneous and sedimentary rocks.
? Main source of the phosphorus used
for making phosphate fertilizers.
Sulfate Mineral Groups
? All sulfate minerals contain the sulfate
anion,(SO4)2-
? Only two are common:
? Anhydrite硬石膏 (CaSO4);
? Gypsum (CaSO4.2H2O).
? Gypsum is the raw material used for
making plaster.
The Ore Mineral Group—
Our Source for Metals
? Sulfides:
? Pyrite (FeS2) and Pyrrhotite 磁黄铁矿 (FeS)
are the most common.
? Galena方铅矿 (PbS),sphalerite闪锌矿 (ZnS),
chalcopyrite黄铜矿 (CuFeS2).
? Familiar metals extracted from sulfide
ore minerals are cobalt,mercury,
molybdenum钼,and silver.
Oxides
? Oxides;
? The iron oxides,magnetite (Fe3O4) and
hematite (Fe2O3),are the two most common
oxide minerals.
? Hematite is red when powdered.
? Other oxide ore minerals are,
? Rutile 金红石 (TiO2),the principal source of titanium;
? Cassiterite 锡石 (SnO2),the main ore mineral for tin;
? Uraninite 沥青铀矿 (U3O8),the main source of uranium.
Rocks,Mixtures of Minerals
? Igneous rocks
? Formed by solidification of magma.
? Sedimentary rocks
? Formed by sedimentation of materials
transported in solution or suspension.
? Metamorphic rocks
? Formed by the alteration of preexisting
sedimentary or igneous rocks in response
to increased pressure and temperature.
Distinguishing The Three Rock Types
The differences among rock types are identified
by two features.
Texture:
The overall appearance of a rock due to the size,
shape,and arrangement of its constituent
mineral grain.
Mineral assemblage:
The type and abundance of the minerals
making up a rock.
Texture and Mineral Assemblage
? A systematic description of a rock
includes both texture and mineral
assemblage.
? Megascopic textural features of rocks are
those that we can see with the unaided eye.
? Microscopic textural features of rocks are
those that require high magnification to
be viewed.
Thin section
A polished surface
Thin slice viewed under a microscope
Mineral Concentration
? The two most common processes of
concentration of a mineral are:
? Vapors are released by a cooling body of magma.
? A hot saline solution,such as heated seawater,
reacts with and alters a rock,and in the process
extracts the scarce metals.
? As such a solution cools the metals are deposited in
veins.
The rock cycle
Frequency of rock types
Rocks,Earth’s Building Materials
? Mineral
? Naturally formed,inorganic,solid material with a
specific chemical composition and a characteristic
crystalline structure.
? Rock
Naturally formed,coherent mass of one or more
minerals,sometimes including organic debris.
Introduction, What Is A Mineral?
Key Characteristics of Minerals
? Minerals have two key characteristics.
? Composition:
? The chemical elements that compose a mineral,
and their proportions.
? Crystal structure:
? The organized way in which the atoms of the
elements are packed together in a mineral.
Composition of Minerals
? A few minerals are composed of a single
element (diamond,graphite,gold,copper,
and sulfur).
? Most minerals are compounds,containing
more than one element.
? Chemical elements are the most
fundamental substances into which matter
can be separated by chemical means,
Crystal Structure of Minerals
? The atoms in most solids are organized in
regular,geometric patterns,called the crystal
structure.
? Solids that have a crystal structure are said to
be crystalline.
? Ice in a glacier meets the definition of a mineral.
? Solids that lack crystal structures are amorphous.
? glass and amber.
Crystal Form
? Crystal,any solid body that grows
with planar surfaces.
? The interfacial angle in any crystalline
structure remains constant.
Iregular Growth of Quartz grains
Fibers of Chrysotile Asbestos
Growth Habit and Polymorphism
? Growth habit:
? The characteristic crystal form of each mineral.
? Polymorphism:
? Some elements and compounds form two or
more different minerals:
? C Graphite,Diamond
? CaCO3 Calcite,Aragonite
? FeS2 Pyrite,Marcasite 白铁矿
? SiO2 Quartz,Cristobalite 方英石
Cleavage
? Cleavage is the tendency to break in preferred
directions along bright,reflective planar surfaces.
? A cleavage surface is a breakage surface,
whereas a crystal face is a growth surface.
? The planar directions along which cleavage
occurs are governed by the crystal structure.
? They are planes along which the bonding between
atoms is relatively weak.
Mineral cleavage--Halite three
well defined cleavage
Luster
? Luster is the quality and intensity of light
reflected from a mineral.
? The most important lusters are:
? Metallic (polished metal surface).
? Vitreous (glass).
? Resinous (resin),the look of dried glue or amber.
? Pearly (pearl),the iridescent闪广的 look of a pearl.
? Greasy (as if the surface were covered by a film of
oil),
Quartz has a vitreous luster
Sphalerite 闪锌矿 has a resinous luster
Talc has a pearly luster
Color and Streak
? Color is determined by several factors,but its
main cause is chemical composition.
? Unreliable for identification.
? Streak is the thin layer of powdered material
left when a specimen is rubbed on an unglazed
ceramic plate,
? Much more reliable than color for identification.
Hardness and the Mohs Scale
? Hardness is a mineral’s relative
resistance to scratching.
? The Mohs relative hardness scale uses ten
minerals,each with its distinctive
hardness:
? scale indicate relative hardness.
? 10.diamond
? 9.Corundum
? 8.Topaz
? 7.Quartz
? 6.Potassium feldspar Pocket knife and glass
? 5.Apatite
? 4.Fluorite Copper penny
? 3.Calcite fingernail
? 2.Gypsum
? 1.Talc
Mohs relative hardness scale
Density and Specific Gravity
? Density is mass per unit volume.
? Minerals with a high density,such as
gold,contain atoms with high mass
numbers that are closely packed.
? Minerals with a low density,such as ice
have loosely packed atoms.
? The unit of density is gram per cubic
centimeter (g/cm3).
Specific Gravity
? Density is easily measured using the
property called specific gravity.
? Specific gravity is the weight of a
substance in air divided by the weight of
an equal volume of pure water.
? Specific gravity is a ratio of weight.
Common Minerals in Earth’s Crust
? Only 12 elements occur in the continental crust
in amounts greater than 0.1 percent by weight.
? These 12 elements make up 99.23 percent of the
crustal mass.
? The crust,therefore,is constructed mostly of a
limited number of minerals.
? Approximately 4,000 minerals have been
identified,but only about 30 are commonly
encountered.
Average composition of the continental crust
Three Mineral Groups
? Silicate minerals (SiO4)4-,the most
abundant in Earth’s crust.
? Carbonate (CO3)2-,phosphate (PO4)3-,
and sulfate (SO4)2- minerals.
? Ore minerals,sulfides (S2-) and oxides
(O2-) that contain valuable metals.
Silicates,The Largest Mineral Group
? Two elements,oxygen and silicon,make up
more than 70 percent of the weight of the
continental crust.
? Polymerization 集合 is the creation of
compounds by accepting or sharing
electrons,
? Linking silicate tetrahedra by oxygen
sharing results in huge anions.
? It produces endless chains.
Silicate Tetrahedron
Olivines and Garnets
? Two very important rock-forming mineral
groups,the olivines and the garnets,have
crystal structures in which the silicate
tetrahedra are isolated.
? Olivine is among Earth’s most abundant
mineral groups,a very common constituent of
igneous rocks in oceanic crust and the upper
part of the mantle.
olivine
Olivines and Garnets (2)
? Olivine occurs in such flawless and
beautiful crystals that is used as a gem,
peridot,
Chains,Pyroxenes and Amphiboles
? One of the most important mineral groups,the
pyroxenes,contains single-chain linkages.
? The most common pyroxene is called augite.
? A very common and important family of
minerals,the amphiboles,contains double
chains.
? The most common of the amphiboles is called
hornblende.
Large Anions formed by polymerization
Chains,Pyroxenes and Amphiboles
? The pyroxenes and the amphiboles are
hard to tell apart.
? The cleavages in pyroxene are right
angles (90o).
? The cleavages in amphibole are at 120o.
Cleavage in the chain silicates
Common silicate minerals
Sheets,Clays,Micas,Chlorites,and
Serpentines
? Kaolinite,Al4Si4O10(OH)8,is one of the
most common clays.
? Muscovite,KAl2(Si3Al)O10(OH)2,is a
common mica.
? Chlorite,which contains Mg2+ and Fe2+
cations,is usually greenish in color.
Crystals of the clay mineral Kaolinite
Sheets,Clays,Micas,Chlorites,and
Serpentines (2)
? The serpentine group consists of three
polymorphs with the formula
Mg6Si4O10(OH)8.
? Chrysotile 温石棉 is the white asbestos of
commerce,
Quartz
? Quartz is pure SiO2.
? Forms six-sided crystals.
? Found in many colors.
? The colors come from minute amounts of iron,
aluminum,titanium,and other elements
present by ionic substitution.
? Fine grain forms of quartz are called
chalcedony玉髓,
? Agate 玛瑙
? Flint 燧石 (gray)
? Jasper 碧玉 (red)
The colors of Quartz
The Feldspar Group — Most Common
Minerals in Earth’s Crust
? The most common mineral group in Earth’s
crust.
? Accounts for about 60 percent of all minerals
in the continental crust.
? Feldspar and quartz constitute 75 percent of
the volume of the continental crust.
? Feldspar has a structure formed by
polymerization.
Green feldspar/amazonite
The Carbonates Group
? The carbonate anion,(CO3)2-,forms
three common minerals:
? Calcite
? Aragonite
? Dolomite
? Calcite reacts vigorously to HCl.
Calcite and dolomite are differ with fizz and effervesce
The Phosphate and Sulfate Mineral Groups
? Apatite is the most important
phosphate mineral.
? Contains the complex anion ((PO4)3-.
? Common mineral in many varieties of
igneous and sedimentary rocks.
? Main source of the phosphorus used
for making phosphate fertilizers.
Sulfate Mineral Groups
? All sulfate minerals contain the sulfate
anion,(SO4)2-
? Only two are common:
? Anhydrite硬石膏 (CaSO4);
? Gypsum (CaSO4.2H2O).
? Gypsum is the raw material used for
making plaster.
The Ore Mineral Group—
Our Source for Metals
? Sulfides:
? Pyrite (FeS2) and Pyrrhotite 磁黄铁矿 (FeS)
are the most common.
? Galena方铅矿 (PbS),sphalerite闪锌矿 (ZnS),
chalcopyrite黄铜矿 (CuFeS2).
? Familiar metals extracted from sulfide
ore minerals are cobalt,mercury,
molybdenum钼,and silver.
Oxides
? Oxides;
? The iron oxides,magnetite (Fe3O4) and
hematite (Fe2O3),are the two most common
oxide minerals.
? Hematite is red when powdered.
? Other oxide ore minerals are,
? Rutile 金红石 (TiO2),the principal source of titanium;
? Cassiterite 锡石 (SnO2),the main ore mineral for tin;
? Uraninite 沥青铀矿 (U3O8),the main source of uranium.
Rocks,Mixtures of Minerals
? Igneous rocks
? Formed by solidification of magma.
? Sedimentary rocks
? Formed by sedimentation of materials
transported in solution or suspension.
? Metamorphic rocks
? Formed by the alteration of preexisting
sedimentary or igneous rocks in response
to increased pressure and temperature.
Distinguishing The Three Rock Types
The differences among rock types are identified
by two features.
Texture:
The overall appearance of a rock due to the size,
shape,and arrangement of its constituent
mineral grain.
Mineral assemblage:
The type and abundance of the minerals
making up a rock.
Texture and Mineral Assemblage
? A systematic description of a rock
includes both texture and mineral
assemblage.
? Megascopic textural features of rocks are
those that we can see with the unaided eye.
? Microscopic textural features of rocks are
those that require high magnification to
be viewed.
Thin section
A polished surface
Thin slice viewed under a microscope
Mineral Concentration
? The two most common processes of
concentration of a mineral are:
? Vapors are released by a cooling body of magma.
? A hot saline solution,such as heated seawater,
reacts with and alters a rock,and in the process
extracts the scarce metals.
? As such a solution cools the metals are deposited in
veins.
The rock cycle
Frequency of rock types
