Transcript What is Mineralogy

Mineralogy & Petrology
Name : Ronak Thakar
Er.no : 120350106047
Std
: Civil 3rd sem
 Curtains : Mineralogy & Petrology.
 Physical properties of minerals.
 Ouccerance and use of minerals.
 Classification of rocks ( types ).
 Engineering properties of rocks.
 Advantages and Disadvantages of rocks.
 What is Mineralogy ?
•
Mineralogy is that branch of geology , which deals
with formation , occurrence , aggregation , properties
and use of Minerals.
 What is Petrology ?
•
Petrology is that branch of geology , where we can
study about the formation of various types of rocks ,
their mode of occurrence , composition , texture and
structure .
 Physical properties of Mineral :• Minerals generally occur in aggregates of more or
less imperfectly developed . below mentioned physical
properties can be used to classify or distinguish one
mineral from another.
 Color :
• Color is the first thing & one of big reason that
attract people to minerals.
• Many minerals have different colors and some
minerals colors are identical to other minerals colors.
• Some mineral example are as below.
(a) White- calcite, talc , chalk etc.
(b) Green- Flourite, beryl, Microcline etc.
(c) Blue- Sodalite, apatite etc.
(d) Yellow- Sulphure, orpiment, siderite etc.
(e) Red- Jasper, orthoclase, zircon etc.
(f) Lead grey- Galena, graphite etc.
(g) Colorless- Halite, quartz, calcite etc.
 Luster :• Luster is a description of the way light interacts
with the surface of a crystal.
• It has nothing to do with color or shape, but is
related to transparancy surface conditions. It's property
are Adamantine , Dull , Earthy , Fibrous , Greasy ,
Gumdrop , Metallic , Pearly , Pitchy Resinous Silky ,
Submetallic , Vitreous , Waxy.
Form & Structure :
Acicular- long and needle-like, thinner than prismatic but
thicker than fibrous.
Bladed- Elongated and flattened like a blade of grass.
Blocky- Rectangular & box. but not flat.
Equant- Any three perpendicular axis through the crystal
are more or less equal.
Fibrous- Thinner than acicular crystals in either individual
crystals or in a tight compact cloth-like mass.
 Cleavage :
It is defined as the tendency of a crystal mineral to
break definite directions yielding on plane smooth surface.
• A mineral may have cleavage in one , two or three
directions.
 Fracture :The appearance of broken surface of a mineral in a
direction other than that of cleavage is generally expressed
by fracture.
• In some cases fracture becomes a characteristic property
of a mineral.
• Common types of Fractures are Even , Uneven ,
Concoidal , Splintery , Hackly , Earthy .
Hardness :
Hardness is determined byscryatching the minerals
with a mineral or substance of known hardness.
• Hardness is determined on the basis of Moh's relative
scale.
 Specific Gravity :
Density refers to the mass per unit volume.
• Specific Gravity is the relative density.
• weight of substance divided by the weight of an equal
volume of water.
Classification of Rocks:1) Igneous Rocks or Primary Rocks.
2) Sadimentary Rocks or Secondary Rocks
3) Metamorphic Rocks.
 These are the rocks formed by the solidification of magma.
 They are devided in to two groups.
a) Intrusive bodies :
Rocks which are formed underneath the surface of the
earth.
b) Extrusive bodies :
These are due to the consolidation of megma above the
surface of the earth.
 These are also known as Volcanic Rocks.
 Important Features of Igneous Rocks :1) Generally hard, massive, compact with
interlocking grains.
2) Entire absence of fossils.
3) Absence of bedding planes.
4) Enclosing rocks are baked.
5) Usually contain much feldspar.
Structure of Igneous Rocks :
The structures of igneous rocks are large scale
features, which are dependent on several factors like :
a) Composition of magma.
b) Viscosity of magma.
c) Temperature and pressure at which cooling and
consolidation takes place.
d) Presence of gases and other volatiles.
 Texture of Igneous Rocks :Textures of igneous rocks describe the actual
relation between crystals or that between the crystals
and the glassy material present within igneous rocks.
Sedimentary Rocks :
Sedimentary rocks are secondary rocks, which are
constituted of sediments.
The sediments are formed by the mechanical or
chemical activities of the natural agencies like running
water , blowing wind , percolating water , glaciers etc,
which causes disintegration as well as decomposition of the
pre-existing rocks.
•
Classification of Sedimentary Rocks :
Sedimentary Rocks are classified as.
a) the genetic aspect of the sediments,
b) their textural characteristics,
c) their mineralogical composition as well as
d) their structural peculiarities.
Texture of Sedimentary Rocks
The word 'Texture' refers to the size , shape , packing
and fabric of the components of the rock.
• It classified as
1) clastic rocks or exogenetic
2) Non-clastic or endogenetic rocks .
Metamorphic Rocks :Metamorphic rocks which are derived from igneous
rocks are known as orthometamorphic , and those which are
derived from the sedimentary rocks , are known as
parametamorphic rocks.
• Agents and kind of Metamorphism
The agents which are mostly responsible for bringing
about metamorphic changes are as follows
1) Temperature
2) Pressure
a) hydrostatic or uniform pressure,
b) directed pressure or stress.
3) Chemically active fluids.
1) Temperature :
It may be supplied by geothermal gradient , magmatic
heat, frictional beats and by radioactive disintegration.
- The temperature range withun which metamorphic
change take place is from 200' to 700'c. however , in certain
cases a temperature of 1000 to 1200'c may be encountered.
2) Pressure :
Uniform Pressure :
It is the hydrostatic pressure which increases with
depth.
- Uniform pressure and temperature can both domainate
together at great depths.
Directed pressure :
It is produced mostly by orogenic movements.
- It dominates at or near the surface.
3) Chemically active fluids :
- these are from the following source.
a) Meteoric water.
b) Juvenile water.
- Water carries minerals in some cases in solution and
also serves us a medium in which chemical changes occur
with ease.
Rocks :1) Granite :
a) Color : Light Color
b) Structure : Massive e Crystalline
c) Texture : the given rocks is hollow - crystalline .
d) Use : Good building stones and road metals , table
tops , kitchen tops etc.
e) Occurrence : Granites mostly occurs in form of stocks
, bosses & balholiths.
2) Basalt :
a) Color : Dark
b) Structure : Massive crystalline.
c) Texture : The given rocks specimen is fine grained
mero crystalline and aphanitic in texture .
d) Name : The given rock specimen is volcanic igneous
rock known as BASALT.
3) Sandstone :
a) Texture : Rock is compact , hard , homogeneous , non
crystalline.
b) Uses : Used as good building stone , road metals etc.
c) Note : Sometimes stratified structure may be present
and hence rock is called 'stratified sandstone'.
4) Marble :
- Metamorphosed limestone or dolostone.
- Non-foliated.
- Composed essentially of calcite or dolomite crystals.
- Coarse, crystalline.
- Used as decorative and monument stone, table top.
- Exhibits a variety of colors.
Rock cycle :-