Presentation on rock forming minerals,ore forming minerals and it's uses.

1. MINERALOGY
BY
G. Ramya Sunil
Assistant Professor
CIVIL Department

2. MINERALOGY
 MINERALOGY: Scientific discipline that is concerned with all aspects
of minerals, including their physical properties, chemical
composition, internal crystal structure, and occurrence and
distribution in nature and their origins in terms of the physicochemical
conditions of formation.
 MINERAL : A Mineral may be defined as a natural, inorganic,
homogeneous solid substances having a definite chemical composition
and regular atomic structure
• Based on their nature and economic importance all minerals are
grouped into
• Rock forming minerals and
• Economic minerals


3.  Rock forming minerals:
 Rock forming minerals are very abundant in the earth’s crust. These
minerals are responsible for the formation of rocks.
 Example: Quartz, Feldspar, Flint, jasper, Olivine, Augite, Hornblende,
Muscovite, Biotite, Asbestos, Chlorite, Kyanite, Garnet, Talc, Calcite,
etc..
 Economic minerals:
 Those minerals are extracted from the earth by mining, quarrying and
pumping. These minerals are responsible for the formation of ore
deposits
 Example: Pyrite, Hematite, Magnetite, Chromite, Galena, Pyrolusite,
Graphite, Bauxite, Magnesite etc..

4. Different Methods Of Study Of Minerals
 According to the definition every mineral has its own chemical
composition and atomic structure. This combination of chemical
composition and atomic structure is unique for every mineral. This fact
facilitates the study of minerals in different ways . Common methods
of study and identification of minerals are based on
 I) Study of Physical properties
 II) Study of Chemical composition
 III) Study of Optical properties
 IV) Study of X-ray analysis

5. Physical properties of minerals
 Physical properties of minerals are like color , lustre, hardness, specific
gravity etc.
 These properties are dependent on chemical composition and atomic
structure
 If atomic structure and chemical composition remain the same the
resulting physical properties also should be same
 Since every mineral has its own chemical composition and atomic
structure

6.  Example: Quartz
 Color: white
 Lustre: vitreous
 Hardness: 7
 Specific gravity :2.65
 Cleavages: Absent
 Fractures : present etc..
 This set of physical properties is never
exhibited by any other mineral . Therefore
if such properties are observed in any
unknown mineral it must be only quartz
and no other mineral.

7. Study of chemical composition
 According to the definition every mineral is expected to have its own
distinctive, chemical composition. Which is not to be found in any
other mineral.
 Therefore by chemical analysis. If the composition is known it should
be possible to identify the mineral
 This principle is the basis for this type of study of minerals
 For example if the composition of an unknown mineral is found to be
calcium carbonate caco3 then that mineral must be only calcite
because calcite always has the composition of calcium carbonate and
no other mineral has this composition

8. Study of chemical composition
 According to the definition (except
polymorphism minerals)every mineral
is expected to have its own distinctive,
chemical composition. Which is not to
be found in any other mineral.
 Therefore by chemical analysis. If the
composition is known it should be
possible to identify the mineral
 This principle is the basis for this type
of study of minerals
 For example if the composition of an
unknown mineral is found to be
calcium carbonate caco3 then that
mineral must be only calcite because
calcite always has the composition of
calcium carbonate and no other
mineral has this composition

9. Study of Optical properties
 When polarized light passes through thin
section of a mineral it is influenced in a
characteristic way depending on the
chemical composition and atomic
structure of the mineral.
 The optical properties of every mineral
are also distinctive and hence helpful in
the identification of mineral
 For example; The set of optical properties
distinctive of quartz are anhedral shape
,colorless, cleavages, low relief, non
pleochroic, no alteration etc.

10. Study of X-ray analysis
 X- ray analysis makes use of the
definite atomic structure found in every
mineral
 When a beam of x-rays falls on a crystal
it is diffracted by the layers of atoms
with in the crystal. In making an x-ray
analysis of the atomic structure of the
crystal the diffracted x-rays are allowed
to fall on a photographic plate, and the
resulting photograph shows a series of
spots or lines which are more are less
symmetrical pattern. From
measurements made on the
photograph
 X-ray analysis will reveal their actual
atomic structure , which is distinctive
for each mineral. This enables the
accurate identification of minerals

11. Advantages of study of physical properties of minerals
 Study of mineral in field itself
 Quickest method
 No need of chemicals
 No loss or wastage of minerals
 Does not require any equipment
 Cheapest ,simplest and lest tedious

12. SIGNIFICANCE OF DIFFERENT PHYSICAL PROPERTIES IN MINERAL
IDENTIFICATION
 Color, luster, streak, hardness, cleavage, fracture, specific gravity and form are
the most useful physical properties for identifying minerals
 COLOR: This is the first observation made in examine a minerals. Color is the
most readily apparent property of a mineral. but be careful Slight impurities or
defects within the crystal structure determine the color of many minerals.
 Example:
Mineral name Color
Quartz White or colorless
Muscovite Silvery white in color
Biotite Black color
Galena Lead gray

13. Lustre: Lustre is the nature of shining on the surface of the mineral
LUSTRE TYPE MINERAL EXAMPLES
Metallic Galena , pyrite, gold
Sub metallic Hematite, chromite, ilmenite ,
magnetite
Vitreous Quartz, calcite, dolomite, feldspar,
barytes etc..
Sub vitreous Pyroxenes and amphiboles
Pearly Talc, muscovite mica
Silky Asbestos, satin spar
Resinous Opal, agate, chalcedony
Greasy Graphite, serpentine
Adamantine Garnet, sphene, zircon, diamond
Earth or Dull Magnesite, kaolin, chalk, bauxite

14.  Streak: The color of a mineral powder is
called streak of a mineral this phenomenon
is more constant and hence more reliable
than color
 In general the powder of a mineral will have
a pale shade of the body color itself
 You can observe a mineral’s streak by
rubbing a mineral against a piece of
unglazed porcelain plate called a streak
plate

15.  HARDNESS: Hardness is the
resistance of a smooth surface to
abrasion or scratching.
 To determine the hardness of a
mineral, something with a known
hardness is used to scratch, or be
scratched by, the unknown. The
minerals in the Mohs Hardness
Scale are used as standards for
comparison

16. Specific Gravity
 The specific gravity of a mineral determines how heavy it is by its
relative weight to water. The specific gravity value is expressed upon
how much greater the weight of the mineral is to an equal amount of
water
 Most of the commonly occurring rock forming minerals have a specific
gravity range 2.5-3.5
 While common ore minerals have a specific gravity of over 3.5

17.  FRACTURE: Fracture is the nature of randomly broken surface of a mineral
 Based on the nature of a broken surface, fractures are described as follows
 Even fracture:
 If the broken surface is smooth and plain it is indicates presence of even
fractures
 Example: chalk, magnesite

18.  Uneven fractures: If the broken surface is rough
or irregular and it is indicates presence of uneven
fractures
 Example:
 Hackly fractures: If the broken surface is very
irregular like the end of a broken stick
 Example: Asbestos, tremolite, kyanite

19.  Conchoidal fractures : If the broken surface is
smooth and curved
 Example: Opal volcanic glass
 Sub Conchoidal fractures :
 If the broken surface is smooth and curved
nature is less prominent
 Example: Agate, flint, jasper etc..

20.  Cleavages: A mineral that exhibits
cleavage consistently breaks, or
cleaves, along parallel, flat surfaces
called cleavage planes

21.  FORM: The form represents the
common mode of occurrence of
a mineral in nature
 Acicular Form: Needle-like,
slender and
 Ex: Natrolite and Rutile
 Bladed form: Blade-like, slender
and flattened
 Ex: Actinolite, Kyanite
Natrolite
Actinolite

22.  Botryoidal form:
 Grape-like, hemispherical masses
 Example: Hematite, pyrite, malachite,
Smithsonite, hemimorphite etc..
 Columnar :
 Similar to fibrous: Long, slender prisms
often with parallel growth
 Example: calcite, gypsum etc..

23. B
BIOTITE
 Cubic form: Cube shape
 Ex: Pyrite, Galena Halite
 Foliated or micaceous or lamellar
(layered)form:
 Layered structure, parting into thin sheets
 Ex: mica ( muscovite, biotite) etc..

24. FELDSPAR
 Massive or compact:
 Shapeless, no distinctive external crystal
shape
 Example: limonite, cinnabar, realgar etc..
 Tabular :More elongated than equant,
slightly longer than wide, flat tablet-
shaped
 Example: feldspar, topaz

25. PHYSICAL PROPERTIES OF MINERALS
 The following properties are useful for identification of
minerals:
 Form
 Color
 Streak
 Lustre
 Cleavages
 Fractures
 Hardness
 specific gravity

26. QUARTZ:
 Form : Massive
 Color : White or colorless
 Streak : Color less
 Lustre : Vitreous
 Cleavages : Present
 Fractures : (un even to conchoidal)
 Hardness: 7
 specific gravity : 2.65
 Uses: Quartz used as an abrasive for
sandblasting, grinding glass, and cutting
soft stones etc..

27. Feldspar
 Form : Tabular
 Color : White/ pale color
 Lustre : Vitreous
 Cleavages : Present
 Fractures : Even to uneven
 Hardness: 6
 specific gravity : 2.5-3.0
 Uses : Feldspars are used widely in the
glass and ceramics industries

28. Flint
 Form : Nodular
 Color: Brown
 Lustre: Waxy, Dull
 Cleavages: Absent
 Fractures:
 Hardness: 6½ - 7
 specific gravity:
 Uses : Flint was widely used historically
to make stone tools and start fires.

29. JASPER
 Form: Massive
 Color: Generally red color
 Streak: Brownish
 Lustre: Resinous
 Cleavages: Absent
 Fractures: Conchoidal
 Hardness: 6½ - 7
 specific gravity: 2.5 to 2.9
 Uses: The mineral aggregate breaks
with a smooth surface and is used
for ornamentation or as a
gemstone.

30. OLIVINE
 Form: Massive
 Color: Olive green
 Lustre: Dull
 Cleavages: Absent
 Fractures: Uneven
 Hardness: 6-7
 specific gravity: 3.2-3.5
 Uses: Most olivine is used in
metallurgical strategies as a slag
conditioner. Olivine has also been
used as a refractory material. It is used
to make refractory brick and used as a
casting sand.

31. AUGITE
 Form: Massive
 Color : Black
 Lustre: Vitreous to sub vitreous
 Cleavages: Present(Distinct/Good)
 Fractures: Uneven
 Hardness: 5-6
 specific gravity : 3.2-3.5
 Uses : The calcium content of augite has
been found to be of limited use in studies of
the temperature history of igneous rocks

32. HORNBLENDE
 Form: Granular
 Color: dark greenish black
 Lustre: Vitreous to sub vitreous
 Cleavages: Present (2 sets)
 Fractures: Uneven
 Hardness: 5 to 6
 specific gravity : 3.0-3.5
 Uses : rushed and used as road
construction and railway ballast.
 It was cut to be used as a dimension
stone.

33. MUSCOVITE
 Form: Lamellar
 Color: Silvery white or colorless
 Lustre: Pearly
 Cleavages: Present (1-set)
 Fractures: Uneven to Hackly
 Hardness: 2-3
 specific gravity : 2.7-3.0
 Uses : muscovite are used
as fillers and extenders in a variety
of paints, surface treatments, and
manufactured products.

34. BIOTITE
 Form: Lamellar or flaky
 Color: Dark greenish black or black
 Lustre: Dull
 Cleavages: Present (1-set)
 Fractures: Uneven to Hackly
 Hardness:2.5 to 3
 specific gravity : 2.7 to 3.4
 Uses : Very little industrial Biotite is
commonly used to limit the age of rocks
through potassium-argon escort or argon-
argon escort. use

35. ASBESTOS
 Form: Fibrous
 Color: White or pale colors
 Lustre: Silky
 Cleavages: Present
 Fractures: Uneven to Hackly
 Hardness: ----
 specific gravity : ----
 Uses : asbestos has been used
building materials, pipe work lagging,
insulating mattresses and rope, fire
resistant insulation boards, sprayed
fire-proofing products, floor tiles

36. CHLORITE
 Form: Foliated
 Color: Various shades of green.
 Lustre: Pearly
 Cleavages: Perfect in one direction
 Fractures: Uneven
 Hardness: 2 to 3
 specific gravity : 2.6 to 3.3
 Uses :Very few industrial uses. Used as a
filler and as a constituent of clay.

37. KYANITE
 Form: Bladed
 Color: Blue with dark patches
 Lustre: Vitreous, pearly
 Cleavages:
Perfect in two directions
 Fractures: Uneven
 Hardness: 4.5 to 5
 specific gravity : 3.5 to 3.7
 Uses : Kyanite is used to fabricate a
wide variety of products.

38. Garnet
 Form: Granular
 Color: Brown
 Lustre: Vitreous to resinous
 Cleavages: Absent
 Fractures: Present
 Hardness: 6-7
 specific gravity : 3.5-4.3
 Uses :Red garnets were the maximum
normally used gemstones. Garnet sand
is also used for water filtration media

39. Talc
 Form: Foliated
 Color: White
 Lustre: Pearly
 Cleavages: {resent (1- set)
 Fractures: Uneven
 Hardness: 1
 specific gravity : 2.7-2.8
 Uses :In the making of paper, paint,
plastic, electric, food, medicine,
cosmetics and ceramics.

40. Calcite
 Form: Rhombic
 Color: Colorless or white
 Lustre: Vitreous
 Cleavages:
 Fractures: Uneven to subconchoidal
 Hardness: 3
 specific gravity : 2.7-2.8
 Uses : Used in paper industry, paint
industry, tire industry, plastic industry
etc..

41. Pyrite
 Form: Cubic
 Color: Pale brass-yellow
 Lustre: Metallic
 Cleavages: preset(3- sets)
 Fractures: uneven
 Hardness: 6–6.5
 specific gravity: 4.95–5.10
 Uses: it is used as an ornamental stone, as
well as a very popular stone for amateur
collectors. It is sometimes used as gemstone
by being faceted and polished for use as an
inexpensive side gemstone in some rings,
necklaces, and bracelets.

42. HEMATITE
 Form: Massive
 Color: Metallic gray
 Lustre: Metallic to sub metallic
 Cleavages: Absent
 Fractures: Uneven, Sub- Conchoidal
 Hardness: 6.5
 specific gravity: 5.26
 Uses: It is the main iron ore in the world.
It is also useful as a ballast for ships,
Polishing compounds, Minor gemstone


43. MAGNETITE
 Form: Granular
 Color: Black
 Lustre: Metallic
 Cleavages: Absent
 Fractures: Uneven
 Hardness: 5-6
 specific gravity: 5.17–5.18
 Uses: Magnetite is an important material
component of power plants as it is used to
generate electricity. And also used in
compasses and other navigation devices

44. Galena
 Form: Cubic
 Color: Lead gray
 Lustre: Metallic
 Cleavages: Present (3-sets)
 Fractures: Rarely found
 Hardness: 2.5–2.75
 specific gravity: 7.2–7.6
 Uses: Galena is the primary ore of lead. It is
used in a green glaze applied to pottery.
Another use of Galena was its importance in
early radio devices.

45. PYROLUSITE
 Form: Massive
 Color: Dark brownish black
 Lustre: Dull
 Cleavages: Indistinct
 Fractures: Uneven
 Hardness: 4-5
 specific gravity; 5.2
 Uses: Pyrolusite is one of the most
important ores of manganese. It is also a
component of the production of steel, and
was once used for the manufacture of
batteries. It is also used in the preparation of
chlorine, and as an agent in coloring and
dyes.

46. Graphite
 Form: Massive
 Color: Black
 Lustre: Greasy
 Cleavages: Perfect in one direction
 Fractures: Uneven
 Hardness: 1-2
 specific gravity: 2.0-2.3
 Uses: Natural graphite is mostly used for
refractories, batteries, steelmaking, expanded
graphite, brake linings, foundry facings and
lubricants.

47. Magnesite
 Form: Massive
 Color: White
 Lustre: Dull
 Cleavages: Absent
 Fractures: Uneven to sub conchoidal
 Hardness: 4-5
 specific gravity: 3.0-3.2
 Uses: Commonly used in making the
bricks used to line kilns, industrial
ovens, and blast furnaces

48. BAUXITE
 Form: Spongy
 Color: Dirty white with patches of different
colors
 Lustre: Dull
 Cleavages: Absent
 Fractures: Uneven
 Hardness: 4
 specific gravity: 2.0-3.5
 Uses: Bauxite is used in a lot of industries
like the chemical industry, refractory,
abrasive, cement, steel, and petrol industry.