Download 02 Chapter 2_Matter and Minerals

Engineering Geology
CVL 3315
Chapter 2
Matter and Minerals
Dr. Sari Abusharar
University of Palestine
Faculty of Applied Engineering and Urban Planning
Civil Engineering Department
2nd Semester 2014-2015
1
Outline of Presentation
Minerals: Building Blocks of Rocks
Atoms: Building Blocks of Minerals
Why Atoms Bond
Isotopes and Radioactive Decay
Physical Properties of Minerals
Mineral Groups
Common Silicate Minerals
Important Nonsilicate Minerals
2
Minerals: Building blocks of rocks
Mineral, is defined as:
•
•
•
•
Naturally occurring
Inorganic solid substance
Orderly crystalline structure
Can be represented by a chemical formula
Rock, is defined as:
A solid aggregate or mass of minerals that
occurs naturally as part of our planet
Halite mineral
Granite rock
Composition of minerals
Elements
• Basic building blocks of minerals
• Over 100 elements are known (92
naturally occurring)
Atoms
• Smallest particles of matter
• Retains all the characteristics of an
element
6
The Periodic Table
Composition of minerals
Atomic structure
• Central region called the nucleus
– Consists of protons (positive charges) and
neutrons (neutral charges)
• Electrons
– Negatively charged particles that surround
the nucleus
– Located in discrete energy levels called shells
Idealized structure of an atom
Why Atoms Bond
Chemical bonding ‫الترابط الكيميائي‬
Ionic bonding ‫الترابط األيوني‬
Covalent bonding ‫الترابط التساھمي‬
Metallic bonding ‫الترابط الفلزي‬
Why Atoms Bond
Chemical bonding ‫الترابط الكيميائي‬
• Formation of a compound by combining
two or more elements
Ionic bonding ‫الترابط األيوني‬
• Atoms gain or lose outermost electrons to
form ions
• Ionic compounds consist of an orderly
arrangement of oppositely charged ions
Halite (NaCl) – An example of ionic bonding
Why Atoms Bond
Covalent bonding ‫الترابط التساھمي‬
• Atoms share electrons to achieve electrical
neutrality
• Covalent bonds are generally stronger
than ionic bonds
• Both ionic and covalent bonds typically
occur in the same compound (bonds are
seldom 100% ionic or covalent in
character)
Covalent bonding – sharing of
valence electrons
Formation of a
covalent bond
between two
hydrogen atoms
(H) to form a
hydrogen molecule
(H2)
Covalent bonding in Diamond
Diamond
Why Atoms Bond
Other types of bonding
• Metallic bonding ‫الترابط الفلزي‬
– Valence electrons are free to migrate among
atoms
– Weaker and less common than ionic or
covalent bonds
– This type of bonding is found in metals such
as copper, gold, aluminum, and silver
Isotopes and Radioactive Decay
Isotopes and radioactive decay ‫النظائر واالضمحالل اإلشعاعي‬
• Mass number is the sum of neutrons plus
protons in an atom
• Atomic number is the number of protons
• An isotope is an atom that exhibits variation in
its mass number (has same atomic number)
• Some isotopes have unstable nuclei that emit
particles and energy in a process known as
radioactive decay
‫‪Isotopes and Radioactive Decay‬‬
‫‪Radioactive decay‬‬
‫تحلل تلقائي ألنواع معينة من نويات الذرات إلى واحد أو أكثر من‬
‫نويات عناصر أخرى ‪ ،‬وانطالق طاقة وجسيمات نووية ‪ ،‬مثل‬
‫اضمحالل اليورانيوم –‪ ٢٣٨‬إلى رصاص‪ ، ٢٠٦-‬واضمحالل‬
‫البوتاسيوم‪ ٤٠-‬إلى أرجون‪.٤٠-‬‬
‫‪Isotope‬‬
‫ذرات عنصر لھا نفس العدد الذرى ‪ ،‬وتختلف فى أعداد الكتلة بسبب‬
‫االختالف فى عدد النيترونات فى نواة العنصر ‪.‬‬
Isotopes and Radioactive Decay
For example, carbon has three well-known
isotopes.
One has a mass number of 12 (carbon-12),
another has a mass number of 13 (carbon13), and the third, carbon-14, has a mass
number of 14. Carbon-12 must also have six
neutrons to give it a mass number of 12.
Carbon-14, on the other hand, has six
protons plus eight neutrons to give it a
mass number of 14.
Physical properties of minerals
Optical Properties
LUSTER ‫البريق‬
COLOR ‫اللون‬
STREAK ‫المخدش‬
Crystal Shape or Habit ‫الشكل البلوري‬
Mineral Strength ‫قوة المعدن‬
HARDNESS ‫الصالدة‬
CLEAVAGE ‫االنفصام‬
FRACTURE ‫المكسر‬
Density and Specific Gravity
Other Properties of Minerals
Physical properties of minerals
Primary diagnostic properties
• Determined by observation or performing a
simple test
• Several physical properties are used to
identify hand samples of minerals.
Physical properties of minerals
Luster ‫… البريق‬
‫درجة وشدة انعكاس الضوء من سطح معدن‬
• Appearance of a mineral in reflected light
• Two basic categories
– Metallic ‫فلزي‬
– Nonmetallic ‫الفلزي‬
• Other terms are used to further describe
luster such as vitreous ‫زجاجي‬, silky ‫حريري‬, or
earthy‫ترابي‬
Galena is a lead sulfide (PbS) ‫كبرتيد‬
‫ الرصاص‬that displays metallic luster
The
freshly
broken sample of
galena
(right)
displays a metallic
luster, while the
sample on the left
is tarnished (‫)ملوث‬
and
has
a
submetallic luster.
Quartz,consists of silica, or silicon dioxide
(SiO2), that displays vitreous luster
Physical properties of minerals
Color
• Generally an unreliable diagnostic
property to use for mineral identification
• Often highly variable for a given mineral
due to slight changes in mineral chemistry
• Exotic colorations of some minerals
produce gemstones
Quartz (SiO2) exhibits a
variety of colors
These
samples
include:
• crystal
quartz
(colorless) ,
• amethyst
(purple quartz)
• citrine
(yellow
quartz)
• smoky
quartz
(gray to black).
Malachite, Sulfur, and Azurite
exhibits a variety of colors
Sulfur (bright yellow)
‫الكبريت‬
Azurite (deep blue )
‫الالزورد‬
Malachite (bright green)
Cu2CO3(OH)2 ‫المليكيت‬
Sulfur: used for
Explosives ‫صناعة المتفجرات‬
Fungicides ‫مبيد الفطريات‬
Fertilizers ‫سماد طبيعي أو كيميائي‬
Realgar ‫ زرنيخ أحمر‬used for
arsenic and to give
fireworks the red color
Physical properties of minerals
Streak ‫المخدش‬
• Color of a mineral in its powdered form
• Helpful in distinguishing different forms
of the same mineral
‫ ويحصل عليه بحك المعدن بسطح‬، ‫• لون مسحوق المعدن‬
. ‫خشن صلب‬
A mineral’s streak is obtained by rubbing it
across a streak plate (a piece of unglazed
porcelain)
and
observing
the
color
of the mark it leaves.
Although the color
of a mineral is not
always helpful in
identification,
the
streak can be very
useful.
Crystal Shape or Habit ‫ھيئة البلورة‬
Mineralogists (expert in the
properties and character of
minerals ) use the term crystal
shape or habit to refer to the
common or characteristic shape
of a crystal or aggregate of
crystals.
Some common crystal habits
A. Bladed.
Elongated
crystals that
are flattened
in one
direction.
B. Prismatic.
Elongated
crystals with
faces that are
parallel to a
common
direction.
‫نصلية الشكل‬
‫منشوري‬
C. Banded.
Minerals that
have stripes
or bands of
different color
or texture.
D. Botryoidal.
Groups of
intergrown
crystals
resembling a
bunch of
grapes.
‫شريطية‬
‫عنقودي‬
Physical properties of minerals
Hardness ‫الصالدة‬
• Resistance of a mineral to abrasion or
scratching
• All minerals are compared to a standard
scale called the Mohs scale of hardness
‫ وتقاس الصالدة على مقياس‬. ‫• درجة مقاومة المعدن للكسر أو الخدش‬
‫( أقلھا صالدة بينما يمثل رقم‬١) ‫موھز الذى يشمل عشر درجات يمثل رقم‬
(٢) talc ‫( تلك‬١) :‫ وھى مرتبة كالتالى‬. ‫( أكثر المعادن صالدة‬١٠)
(٥) fluorite ‫( فلوريت‬٤) calcite ‫( كالسيت‬٣) gypsum ‫جبس‬
quartz ‫( كوارتز‬٧) orthoclase ‫( أورثوكالز‬٦) apatite ‫أباتيت‬
‫( الماس‬١٠) corundum ‫( كورندم‬٩) topaz ‫( توباز‬٨)
. diamond
Mohs scale of hardness
• This
property
is
determined by rubbing
a mineral of unknown
hardness against one of
known hardness, or vice
versa.
• It should be noted that
the Mohs scale is a
relative ranking, and it
does not imply that
mineral
number
2,
gypsum, is twice as hard
as mineral 1, talc. In
fact, gypsum is only
slightly harder than talc.
Physical properties of minerals
Cleavage ‫اإلنفصام‬
‫ على امتداد أسطح مستويات ذات‬، ‫ميل المعدن للتكسر في اتجاھات مفضلة‬
‫الروابط الضعيفة‬
..‫الضعيفة‬
• Tendency to break along planes of weak
bonding
• Produces flat, shiny surfaces
• Described by resulting geometric shapes
– Number of planes
– Angles between adjacent planes
Cleavage in Muscovite Mica
The thin sheets
shown here were
produced
by
splitting a mica
(muscovite) crystal
parallel
to
its
perfect cleavage.
Common cleavage directions
When minerals break evenly in more than one direction,
cleavage is described by the number of cleavage directions and
the angle(s) at which they meet.
‫مسكوفيت‬
‫الفلسبار‬
‫ھورنبلند‬
‫‪Common cleavage directions‬‬
‫ھاليت‬
‫كالسيت‬
‫معين األوجه‬
‫فلوريت‬
Three examples of perfect
cleavage – fluorite, halite, and
calcite
fluorite
halite
calcite
‫‪Physical properties of minerals‬‬
‫المكسر‪Fracture‬‬
‫‪• Absence of cleavage when a mineral is‬‬
‫‪broken‬‬
‫• التكسير غير المنتظم للبلورة عبر أسطح ال توازى وجه‬
‫البلورة ‪ ،‬وتستخدم للتفرقة بين المعادن ‪.‬‬
‫مكسر محاري‬
‫‪Conchoidal fracture‬‬
‫تعنى حرفيا "مثل الصدفة”‪ ،‬وھو‬
‫وصف لشكل مكسر بعض‬
‫)مثل‬
‫والمعادن‬
‫الصخور‬
‫األوبسيديان والكوارتز(‪ ،‬والتى‬
‫تأخذ شكل أسطح بھا نتوءات‬
‫منحنية متحدة المركز ‪.‬‬
‫‪The smooth curved surfaces‬‬
‫‪result when minerals break in a‬‬
‫‪glasslike manner.‬‬
Physical properties of minerals
Density ‫الكثافة‬
• An important property of matter, is defined as
mass per unit volume.
Physical properties of minerals
Specific Gravity
• Ratio of the weight of a mineral to the
weight of an equal volume of water
• Most minerals are between 2 and 3.
• Average value is approximately 2.7
• Quartz has a specific gravity of 2.65
• Galena, an ore of lead, has a specific
gravity of roughly 7.5
• 24-karat gold is approximately 20
Physical properties of minerals
Other properties
•
•
•
•
•
•
•
Magnetism ‫المغناطيسية‬
Reaction to hydrochloric acid
Malleability‫قابلية التطريق‬
Double refraction
Taste
Smell
Elasticity
‫المغناطيسية ‪Magnetism‬‬
Reaction to hydrochloric acid
One very simple chemical
test involves placing a drop
of dilute hydrochloric acid on
a freshly broken mineral
surface.
Using
this
technique, certain minerals,
called
carbonates,
will
effervesce ‫يفور‬
(fizz) as
carbon
dioxide
gas
is
released
Calcite reacting with a weak
acid
Double refraction illustrated by the mineral
calcite.
some minerals exhibit
special
optical
properties.
For
example,
when
a
transparent piece of
calcite is placed over
printed
text,
the
letters appear twice.
This optical property is
known
as
double
refraction.
Mineral Groups
Nearly 4000 minerals have been
identified (named) and several new ones
are identified each year.
Rock-forming minerals
• Common minerals that make up most of
the rocks of Earth’s crust
• Only a few dozen are abundant!
• Composed mainly of the 8 elements that
make up over 98% (by weight) of the
continental crust
Relative abundance of the eight most
abundant elements in the continental crust
Mineral Groups
Silicates
• Most important mineral group
– Comprise most of the rock-forming minerals
– More than 800 silicate minerals are known
– they account for more than 90 percent of
Earth’s crust.
– Very abundant due to large amounts of
silicon and oxygen in Earth’s crust
• silicon-oxygen tetrahedron molecule
– Fundamental building block
– Four oxygen ions surrounding a much
smaller silicon ion
Silicate structures
Two representations of
the
silicon–oxygen
tetrahedron. A. The four
large spheres represent
oxygen ions, and the
blue sphere represents a
silicon ion. The spheres
are drawn in proportion
to the radii of the ions.
B. An expanded view of
the tetrahedron that has
an oxygen ion at each of
the four corners.
Mineral Groups
Joining Silicate structures
• Single tetrahedra are linked together to
form various structures including:
– Independent tetrahedra
– Single chain
– Double chain
– Sheet structure
– Three-dimentional framework
Silicate structures
The relative sizes and charges of ions
commonly found in minerals
Ionic radii are usually expressed in angstroms (1 angstrom equals 10-8cm)
Mineral Groups
The Light Silicates
Or nonferromagnesian. Generally light in
color and specific gravity of about 2.7
Nonferromagnesian minerals
‫ )ﺘﺤﺘوي‬.‫ﻤﻌﺎدن ﺴﻴﻠﻴﻜﺎﺘﻴﺔ ﻤﻜوﻨﺔ ﻝﻠﺼﺨور ﻻ ﺘﺤﺘوى ﻋﻠﻰ اﻝﺤدﻴد واﻝﻤﺎﻏﻨﺴﻴوم‬
(........‫ ﻜﺎﻝﺴﻴوم‬،‫ ﺼودﻴوم‬،‫ﺒوﺘﺎﺴﻴوم‬
Mineral Groups
Common Silicate minerals
• Light silicates: Feldspar Group
– Most common mineral group
– 50 percent of Earth’s crust.
– 3-dimensional framework of tetrahedra
exhibit two directions of perfect cleavage at
90 degrees
– Orthoclase ‫( األورثوكليز‬potassium feldspar)
and Plagioclase ‫( البالجيوكليز‬sodium and
calcium feldspar) are the two most common
members
Common Silicate Minerals
Orthoclase feldspar
Plagioclase feldspar
These parallel lines, called striations (‫)حزوز‬, are a distinguishing
characteristic of plagioclase feldspar.
Mineral Groups
Common Silicate minerals
• Light silicates: Quartz (SiO2) ‫الكوارتز‬
–Only common silicate composed entirely of
oxygen and silicon
–Hard and resistant to weathering
–Conchoidal fracture
–Often forms hexagonal crystals
Common Silicate Minerals
Mineral Groups
Common Silicate minerals
• Light silicates: Muscovite
–Common member of the mica family
–Excellent cleavage in one direction
–Produces the “glimmering” brilliance ‫ لمعان‬often
seen in beach sand
Common Silicate Minerals
Dark silicates
Light silicates
Mineral Groups
Common Silicate minerals
• Light silicates: Clay minerals
– Clay is a general term used to describe a
variety of complex minerals
– Clay minerals all have a sheet or layered
structure
– Most originate as products of chemical
weathering
The Dark Silicates
Or ferromagnesian, contains ions of
iron=ferro and/or magnesium. Because that
content they are dark in color and have a
greater specific gravity.
Ferromagnesian minerals ‫ﻤﻌﺎدن اﻝﻔﻴروﻤﻐﻨﻴﺴﻴﺔ‬
. ‫ أو اﻝﻤﺎﻏﻨﺴﻴوم‬/‫ﻤﻌﺎدن ﺴﻴﻠﻴﻜﺎﺘﻴﺔ ﻤﻜوﻨﺔ ﻝﻠﺼﺨور ﺘﺤﺘوى أﺴﺎﺴﺎ ﻋﻠﻰ اﻝﺤدﻴد و‬
‫وﻴﺴﺘﺨدم ﻫذا اﻻﺴم ﻝوﺼف اﻝﻤﻌﺎدن اﻝﺸﺎﺌﻌﺔ ﻤﺜل اﻷوﻝﻴﻔﻴن واﻝﻬﺒرﺴﺜﻴن اﻷوﺠﻴت‬
. ‫واﻝﻬورﻨﺒﻠﻨد واﻝﺒﻴوﺘﻴت‬
Mineral Groups
Common Silicate minerals
• Dark silicates: Olivine group
– a family of high-temperature silicate minerals
– black to olive green in color and have a
glassy luster and a conchoidal fracture
– Individual tetrahedra linked together by iron
and magnesium ions
– Forms small, rounded crystals with no
cleavage
Common Silicate Minerals
Mineral Groups
Common Silicate minerals
• Dark silicates: Pyroxene Group
– Single chain structures involving iron and
magnesium
– Two distinctive cleavages at nearly 90 degrees
– Augite is the most common mineral in the
pyroxene group
Common Silicate Minerals
Mineral Groups
Common Silicate minerals
• Dark silicates: Amphibole Group
– Double chain structures involving a variety of
ions
– Two perfect cleavages exhibiting angles of
120 and 60 degrees
– Hornblende is the most common mineral in
the amphibole group
Common Silicate Minerals
Cleavage angles for augite and hornblende
Mineral Groups
Common Silicate minerals
• Dark silicates: Biotite
–iron-rich member of the mica family
–Excellent cleavage in one direction
- Like hornblende, biotite is a common
constituent of igneous rocks, including the rock
granite.
Common Silicate Minerals
Dark silicates
Light silicates
Mineral Groups
Important nonsilicate minerals
Typically divided into classes based on
anions
Comprise only 8% of Earth’s crust
Often occur as constituents in sedimentary
rocks
Mineral Groups
Important nonsilicate minerals
• Several major groups exist including
– Oxides
– Sulfides
– Sulfates
– Native Elements
– Carbonates
– Halides
‫‪Mineral Groups‬‬
‫سماد‬
‫األصباغ‬
‫خام الحديد‬
‫يستعمل للصنفرة‬
Mineral Groups
Mineral Groups
Important nonsilicate minerals
• Carbonates
– Primary constituents in limestone and
dolostone ‫حجر الدولوميت‬
– Calcite (CaCo3, calcium carbonate) and
Dolomite (Ca,Mg(CO3)2, calcium-magnesium
carbonate) are the two most important
carbonate minerals
Mineral Groups
Important nonsilicate minerals
• Many nonsilicate minerals have economic
value
• Examples
– Hematite (oxide mined for iron ore)
– Halite (halide mined for salt)
– Sphalerite (sulfide mined for zinc ore)
– Native Copper (native element mined for
copper)
– Gypsum (sulfate mined for sheetrock ‫اللوح‬
‫الجصي‬, etc.)
Estimated percentages (by volume) of
the most common minerals in Earth’s crust.
End of Chapter 2