1. UNIT-II MINERALOGY

2. MINERALOGY
A mineral is naturally occurring homogeneous inorganic substance having distinctive physical properties and a more or less definite chemical composition.
Minerals are to a large extent the units which make up the rocks of the earths crust or the outer shell.

3. MODE OF FORMATION OF MINERALS
Three kinds of formation of minerals in nature
Formed from magma
Secondary process
Metamorphism
Directly formed from deposition of molten magma - feldspar, quartz, pyroxenes, amphiboles, micas
Due to weathering, precipitation, deposition (secondary process) – calcite, dolomite, bauxite, coal, petroleum
Formed under the influence of high temperatures and pressures with and without the active involvement of chemically active solution (metamorphism)- Garnets, chlorite, graphite

4. CRYSTALLOGRAPHY
Great majority of minerals when the conditions of formations are favorable, occur in definite and characteristic geometric forms known as crystals.
Crystal-Greek word “Krystallos” meaning clear ice.
The study of crystals is called as crystallography..
“Crystals are bodies bounded by surfaces usually flat, arranged on a definite plan which is an expression of an orderly internal arrangement of the atoms”.

5. CRYSTALLOGRAPHIC ARRANGEMENT

6. SYMMETRY
All crystals show by the arrangement of their faces a definite symmetry which enables one to group them into different classes
Types of symmetry
Plane of symmetry
Axis of symmetry
Centre of symmetry

7. SYMMETRY 1.PLANE OF SYMMETRY
A plane of symmetry divides a crystal into two similar and similarly placed halves
2.Axis of symmetry
If a crystal on being rotated comes to occupy the same position in space more than once in a complete turn the axis about which the rotation has taken Is called as axis of symmetry
3.Centre of symmetry
A crystal is said to have centre of symmetry if an imaginary line can be passed from any point on its surface through its centre and a similar point can be found on the line at an equal distance beyond the centre

8. PHYSICAL PROPERTIES Colour Lustre Structure Hardness Cleavage Fracture
Specific gravity
Tenacity
Odour and taste

9. Colour
very useful in identifying mineral in spite of the fact that colour is constant in most of the minerals and commonly colour is due to stain or impurities in the minerals.
Lustre
Appearance of a fresh surface of a mineral in a ordinary reflected light
Metallic- galena
Glassy-vitreous
Pearly-talc
Structure
Term used to denote the shape and form of minerals.
Columnar
Bladed
Fibrous
Radiated
Lamellar
granular

10. Hardness Resistance a mineral offers to abrasion or scratching and is measure relative to a standard scale of ten minerals known as Moh’s scale of hardness Cleavage Tendency of many crystallized minerals to break or split in certain parallel directions yielding more or less smooth surfaces known as cleavage planes. May be perfect and imperfect Fracture Appearance of the broken surface of the mineral. Specific gravity Specific gravity of a mineral is the ratio of its weight to the weight of an equal volume of water.

11. Tenacity The resistance which the mineral offers to breaking, crushing, bending or tearing-in short its cohesiveness is known as tenacity Ex Brittle, sec tile, malleable, flexible and ductile Taste A few minerals which are soluble in water have more or less characteristic tastes Acid, alkaline, astringent, bitter, cooling, pungent, saline

12. ISOMORPHISM Peculiar natural phenomenon
Minerals appear to be mixtures of two different minerals from chemical composition.
This type of formation is called as isomorphism
Examples: Feldspar, pyroxene, amphiboles and garnets

13. ROCK FORMING MINERALS
Silicate ranks first in the earths crust for rock forming minerals.
SiO4 tetrahedron ins the fundamental unit of all silicate minerals.
STRUCTURE OF SILICATES:
Nesosilicates - SiO4 occurs as Independent unit E.g. garnet.
Sorosilicate - SiO4 occurs as pairs unit E.g. garnet.
Inosilicate SiO4 occurs as chains along one direction or single chain silicates e.g. pyroxenes
Cyclosilicates - SiO4 occurs as ring form as 3 or 4 units called as ring silicates e.g beryl
Phyllosilicates - SiO4 occurs as sheets; called as sheet silicates. E.g mica, chlorite
Tectosilicates - SiO4 occurs as three dimensional frame work e.g quartz, feldspar

14. MINERAL GROUP OR FAMILIES
Some silicate minerals have similar atomic structure and chemical composition. Such set of minerals are called as groups or families.
Examples of some important groups of silicate minerals
Feldspar group
Pyroxene group
Amphibole group
Garnet group

15. IMPORTANT DETAILS OF ROCK FORMING MINERAL
I. FELDSPARS
Most abundant of all the silicate minerals.
The name refers to a group and not a single mineral
Make up about half the rocks of earths crust
Form monoclinic and triclinic crystals and are aluminous silicates of K, Na or Ca.
Three common molecules
Orthoclase - KAlSi3O3
Albite - NaAlSi308
Anorthite - CaAlSi3O8

16. CRYSTAL SYSTEM : MONOCLINIC
Any mineral that falls under the following specifications belongs to the monoclinic crystal system.
Three axes, all of them are unequal in length. Two of them are at right angles to each other, while the third is lies at an angle other than 90°.

17. CHEMICAL COMPOSITION-FELDSPAR
In chemical constitution, felspars are chiefly Alumino-silicates of sodium, potassium and calcium with the following general formula : WZ4 O8
where W=Na ,K, Ca and Ba and Z= Si and Al .
The Si : Al shows a variation of 3:1 to 1:1 .
Some examples of chemical composition of felspar minerals are : KAlSi3O8 – NaAlSi3O8 – CaAl2Si2O8
Occurs in isomorphous series

18. ATOMIC STRUCTURE-FELDSPAR
At atomic level ,the felspars shows a continuous three-dimensional network type of structure in which SiO4 tetrahedra are linked at all the corners, each oxygen ion being shared by two adjacent tetrahedral.
The SiO4 tetrahedra is accompanied by AlO4 tetrahedra so that the feldspar are complex three dimensional framework of the above two types of tetrahedra.
The resulting network is negatively charged and these negative charges are satisfied by the presence of positively charged K, Na, Ca and Ba.
The felspar group of minerals crystallize only in two crystallographic systems Monoclinic and Triclinic.

19. CRYSTALLIZATION
The feldsdpar group of minerals crystallize only in two crystallographic systems Monoclinic and Triclinic.
CLASSIFICATION
Chemically felspar fall into two main groups:
The potash felspar
The soda lime felspar .
Common members of the two groups are -
Potash felspar :
Orthoclase (KAlSi3O8), Sanidine(KAlSi3O8) and Microline (KAlSi3O8).
Soda – lime feldspar :
These are also called the plagioclase feldspars and consists of an isomorphous series of six felspar with two components: NAlSi3O8 and Ca Al2 Si2O8 as the end members.
1. Albite Labradorite
2. Oligoclase Bytwonite
3. Andesine Anorthite
The above series is also known as Albite-Anorthite series.

20. Crystallographically ,felspar fall in two crystal systems .
Monoclinic Feldspars
1. Orthoclase (KAlSi3O8 )
2. Sanidine (KAlSi3O8 )
Triclinic Feldspars
1. Microcline (KAlSi3O8 )
2. Albite – Anorthite series (six minerals)-(six minerals)
PHYSICAL PROPERTIES
In addition to their close relationship in chemical composition ,crystallography and atomic constitution ,felspar group of minerals exhibit a broad similarity and closeness in their physical characters as well so that differentiation of one variety from other requires very thorough, sometimes microscopic examination.
Light in colour,
lower specific gravity ,
have a double cleavage and a hardness varying between
COMMON TYPE OF MINERALS
Orthoclase 2. Microcline 3. Albite 4. Anorthite

21. PHYSICAL PROPERTIES-FELDSPAR
Form
Tubular, mineral occurs as uniform thickness
Colour
Generally white, pale grey or pale red
Streak
White or pale body colour
Lustre
Vitreous
Fracture
Even to uneven
Cleavage
Two sets one set is better developed
Hardness 6
Density
Medium, 2.57
Occurrence
weathering

22. Orthoclase Crystal system
Monoclinic ; β=63•57•.Crystals commonly occur in prismatic shape.
Cleavage
Shows cleavage in 2 directions. The one parallel to basal pinacoid (001) is perfect. The cleavage angle is 90•.
Colour
Various shades of pink and red, such as flesh red, reddish white, light pink . The transparent variety is called the Adularia .
Luster
Vitreous to semiviterous.
Hardness and specific gravity
6-6.5 ; 2.56 to 2.58
Composition
KAlSi3O8
Optical
Optically negative (-)
Occurrence
A most common and essential constituent of many igneous rocks ,especially granites .
Economic use
As a ceramic material.
Varieties
Adularia-a transparent orthoclase.
Sanidinc-a high temperature variety stable above 900•C

23. microcline Crystal system
Triclinic, resembles closely with orthoclase in crystal habits.
Cleavage
In two directions, the one parallel to basal pinacoid(001) is perfect.
Colour
Similar to orthoclase. In addition , may occur as a greenish felspar,when it is called amazonite.
Streak ,hardness and specific gravity
colorless, 6-6.5,2.54 to 2.57
Composition
KAlSi3O8
Optical
Optically negative (-).
Occurrence
It occurs along with the orthoclase in granites and other igneous rocks.
Economic use
As a ceramic material and semi-precious stone (amazonite).
Varieties
Anorthoclase (meaning-not orthoclase).It is a triclinic felspar containing sodium aluminum silicate.

24. albite
Crystal system
Triclinic ,it is the first member of the isomorphous plagioclase series .
Cleavage
Present in 2 directions. the one parallel to basal pinacoid (001)is perfect.
Colour
Commonly whitish or pinkish white but shows shades of grey,green and blue.
Streak
Colourless
Luster
Vitreous to pearly.
Hardness and specific gravity
6-6.5 ,
Composition
Sodium aluminum silicate with NaAlSi3O % and CaAl2Si2O %.
Optical
Optically positive(+).
Occurrence
It is an essential constituent of many igneous rocks such as granite,syenites,rhyolites and dacites.
Economic use
As a ceramic material.
As an ornamental stone in polished form.

25. anorthite Crystal system
Triclinic, it is the last member of the isomorphous plagioclase series.
Cleavage
Present in two directions, the one parallel to basal pinacoid (001)if perfect .
Colour
Generally white, may also occur in reddish and light grey shades.
Streak
Colourless
Luster
Semi-vitreous.
Composition
CaAl2Si2O %
Optical
Optically positive (+)
Occurrence
An important constituent of many basic types of igneous rocks.
Varieties
Composition of other members of plagioclase felspars has mentioned above . These maybe broadly considered the varieties of plagioclase felspars.

26. II. QUARTZ Composition of SiO2 Most abundant material next to felspar
Colourless or white
Many coloured varieties are mainly due to impurities.
Three main varieties
Crystalline -Rock crystal, amethyst, rose quartz, milky quartz
Crypto-crystalline -Chalcedony, carnclian
Amorphous-opal
Mostly used for jewellery and ornamental purposes

27. QUARTZ
Crystal system
Hexagonal, (rhombohedral). Crystals common ; some crystals weighing many tones have been reported. Twinned ,right-handed and left-handed crystals are common.
Cleavage
Generally absent
Fracture
Conchoidal
Colour
Colourless when pure, quartz also occur in coloured varieties :red, green , blue and mixture.
Hardness 7
Sp. Gravity
Streak
White in coloured varieties
Varieties
It is a very common rock forming mineral and occurs in numerous varieties . A few common varieties are mentioned below.

28. Polymorphous transformation
Quartz, when heated , transforms into high temperature modifications as follows:
(870•C) (1470•C) (1713•C)
Quartz ↔ Tridymite ↔ Cristobalite ↔ melt
The variety named as QUARTZ itself has two polymorphs :
1. Α quartz, β quartz.
Identification of the exact type of quartz (into Αand β) requires thoroug investigations of the mode of formation of mineral as observed by its place of occurrence and also type of symmetry.
Right handed and left handed quartz :
When occurring, quartz may be distinguished into right handed and left handed types.
Carried out on the basis of recognition of some typical faces such as trigonal, trapezohedron and dipyramid. These two faces normally occur at the edges of the prism faces, one above the another. In the left handed quartz ,these faces are located on the left side of the upper edge of the prism, whereas in the right handed quartz, these occur on the right upper edge of the crystals. Such a location of these faces in manifestation of an internal atomic arrangement in the crystal.

29. COLOURED VARIETIES :
Common pure quartz is a colourless transparent mineral. Presence of even a trace of an impurity may give it a characteristic colour and hence a variety . A few common types of quartz distinguished on their basis are :
Amethyst – purple or violet
Smoky- dark to light brown, even black
Milky- pure white and opaque
Rose red – colour is attributed to presence of titanium.

30. CRYPTOCRYSTALLINE TYPES :
In many cases, crystalline of pure silica to quartz remains incomplete due to interruption in the process for one reason to another. Silica occurring in these cryptocrystalline varieties, although close in composition and physical properties to quartz is named differently. A few common varieties of cryptocrystalline silica are as follows :
Chalcedony – luster ,waxy, commonly translucent, generally massive.
Agate – often banded , opaque and massive.
Onyx – a regularly banded agate having alternating and evenly paced layers of different colours.
Flint – a dull opaque variety of chalcedony breaking with characteristic conchoidal fracture.
Jasper- a dull red, yellow,almost amorphous variety of silica.
OCCURRENCE
Quartz and its varieties occur in all types of rocks ;igneous, sedimentary and metamorphic.
In igneous rocks, quartz makes up bulk of acidic varieties.
In sedimentary rocks quartz makes up sandstones and ortho quartzites.
Loose sands consist mostly of quartz grains.
The metamorphic rocks like gneisses contain good proportion of quartz in some cases.
A metamorphic rock named as (Para) quartzite is entirely made up of quartz.

31. PIEZOELECTRICITY Quartz scepters
Quartz crystals have piezoelectric properties; they develop an electric potential upon the application of mechanical stress. An early use of this property of quartz crystals was in phonograph pickups. One of the most common piezoelectric uses of quartz today is as a crystal oscillator. The quartz clock is a familiar device using the mineral. The resonant frequency of a quartz crystal oscillator is changed by mechanically loading it, and this principle is used for very accurate measurements of very small mass changes in the quartz crystal microbalance and in thin-film thickness monitors.
Quartz scepters

32. PHYSICAL PROPERTIES-QUARTZ
Form
Granular or short prismatic
Colour
Black or dark greenish black; pale colour – magnesium rich pyroxene
Streak
White or pale body
Lustre
Vitreous
Fracture
Uneven
Cleavage
Two sets od prismatic cleavage 87° and 93°
Hardness
5 to 6
Density
Medium
Specific gravity
3.2 to 3.5

33. III. PYROXENE
Constitute important group of minerals that are generally recognized by their stout crystals and their two cleavages right angles to each other.
Most pyroxenes are dark coloured
Ca, Mg and Fe silicate composition
Varieties
Monoclinic pyroxene Augite
Orthorhombic pyroxene Hypersthene

34. CHEMICAL COMPOSITION
Composition mainly consists of silicates of calcium, magnesium and ferrous iron.
At initial formation magnesium rich varieties
At later stage iron rich formation
General formula R2(AlSi)2 where R –divalent calcium, magnesium or ferrous iron
ATOMIC STRUCTURE
Single chain silicates
Have 1:3 ratio of silicon and oxygen
Mostly crystallize in the form of either orthorhombic or monoclinic system

35. Monoclinic pyroxene- AUGITE

36. AUGITE - description Chemical Formula: (Ca,Na)(Mg,Fe,Al)(Al,Si)2O6
Augite is an important rock-forming mineral, and large crystals are fairly common.
It is the most widespread member of the pyroxene group, and it frequently alters to many other minerals, including Hornblende.
Augite usually occurs in dull crystals that are ugly and uninteresting.
The name Augite is derived from the Greek word augites, "brightness", in reference to the bright luster this mineral occasionally exhibits.

37. OCCURRENCE
Major rock forming mineral in mafic igneous rocks, ultramafic rocks and some high grade metamorphic rocks.

38. Crystal System : Monoclinic
Any mineral that falls under the following specifications belongs to the monoclinic crystal system: Three axes, all of them are unequal in length. Two of them are at right angles to each other, while the third is lies at an angle other than 90°.

39. AUGITE – PHYSICAL PROPERTIES
Colour : dark green to black
Streak : white to gray, augite can be slightly harder than a streak plate so brittle fragments rather than a powder will sometimes be produced.
Lustre : vitreous
Diaphaneity : translucent to opaque
Cleavage : prismatic
Hardness : 5.5 – 6
Specific Gravity :
Distinguishing Characteristics : Two cleavage directions almost at right angles, dark green to black colour
Chemical Classification : silicate

40. USES OF AUGITE
Augite is a dark green to black mineral that is used for ceramics.
It contains large amounts of aluminum, iron, and magnesium and can be found in meteroic stones.
ceramic glazing, manufacturing aluminum, purifying water.

41. IV.AMPHIBOLES
Another type of mineral
AMPHIBOLE MINERALS
Important
Crystallization
ORTHORHOMBIC
MONOCLINIC
Crystals – long, slender, prismatic, sometimes fibrous Prism angle – 124’

42. Amphibole Group – Resemble – Pyroxene Group
CHARACTERISTICS
HARDNESS: 5 – 6
SPECIFIC GRAVITY: 3 – 3.5
Dark in Colour
CHEMICAL COMPOSITION
Amphibole minerals – Metal silicates – Si : O – 4 : 11
Ca, Mg, Fe, Mn, Na, K, H – metallic ions
(OH) ions – F and Cl –
Chemical Formula – [Si4 O11]2 [OH]2
Various ions – Al, Mg, Fe, Ca, Na, K, H, F – replaced – giving rise to a variety of Amphibole minerals
ATOMIC STRUCTURE
Difference – Amphiboles and Pyroxenes
Amphiboles – SiO4 tetrahedra – double chains
Reason – more complex than Pyroxenes – chemical composition

43. PHYSICAL PROPERTIES Orthorhombic Amphiboles
Crystallise in only 2 crystal systems
Dark in colour.
Hardness – 5 to 6
Specific Gravity – 2.8 to 3.6
Elongated
Slender
Often fibrous in nature
Orthorhombic Amphiboles
ANTHOPHYLLITE (Mg, Fe)3 [Si4O11]2 [OH]2
CRYSTAL SYSTEM
Orthorhombic – thin, slender fibres
CLEAVAGE
Perfect and Prismatic
COLOR
Grey, brownish or greenish
HARDNESS
5.56 – 6
SP. GRAVITY
2.85 – 3.20
LUSTRE
Vitreous
OPTICAL
Optically (+)
OCCURRENCE
Only in metamorphic rocks

44. VARIETIES OF AMPHIBOLES
Hornblende
Tremolite
Actinolite
Asbestos
Hornblende is the most common variety

45. AMPHIBOLE - 1.Hornblende

46. Hornblende – Description
Chemical formula : Ca2(Mg,Fe)4Al(Si7Al)O22(OH,F)2
Any of a subgroup of amphibole minerals that are calcium-iron-magnesium-rich and monoclinic in crystal structure.
Hornblende, occurs widely in metamorphic and igneous rocks.
Common hornblende is dark green to black in colour and usually found in middle-grade metamorphic rocks (formed under medium conditions of temperature and pressure).
Such metamorphic rocks with abundant hornblende are called amphibolite's.

47. System : Monoclinic
Block diagram showing the relationship between the crystallographic axes and the indicatrix axes.

48. OPTICAL PROPERTIES
Colour : distinctly coloured, shades of green, yellow-green, blue- green and brown
Composition : exhibits a wide range of compositions.
Occurrence : common mineral found in a variety of geological environments, i.e. in igneous, metamorphic and sedimentary rocks
Alteration : may be altered to biotite, chlorite or other Fe-Mg silicates
Distinguishing Features : cleavage and grain shape, inclined extinction, pleochroism

49. PHYSICAL PROPERTIES Colour : dark green to black.
Streak : gray to greenish gray
Lustre : vitreous
Diaphaneity : translucent to nearly opaque
Cleavage : good
Hardness :
Specific Gravity :

50. USES
The hornblende mineral is used in a variety of common things that we use every day.
These things include: steel, soap, oil, buildings, and statues.

51. Monoclinic Amphiboles – 2.Tremolite
Ca2Mg5 [(Si4O11)]2 [OH]2
CRYSTAL SYSTEM
Monoclinic –long, bladed
CLEAVAGE
Prismatic and Perfect
COLOUR
White to light grey
HARDNESS
5.5 – 6.0
SP. GRAVITY
2.9 – 3.0
LUSTRE
Vitreous
OPTICAL
Optically (-)
OCCURRENCE
Igneous and metamorphic rocks.. (mostly)

52. Monoclinic Amphiboles – 3. ACTINOLITE
Ca2 (Mg, Fe)5 [(Si4O11)]2 [OH]2
CRYSTAL SYSTEM
Monoclinic
CLEAVAGE
Perfect and Prismatic
COLOUR
Green due to ferrous ion
HARDNESS
5.5 – 6.0
SP. GRAVITY
3.1 – 3.3
VARIETY
Asbestos – fibrous form – long and flexible fibres

53. V. INTRODUCTION-MICA
Mica is the name given to a group of silicate minerals that have silicon and oxygen as their two major components.
The Mica family of minerals includes several variations based on chemical composition and characteristics.

54. Mica’s are besides feldspars, pyroxenes and amphiboles, very common rock forming minerals comprising approximately 4 percent of the Earth.
They have great variation in their Chemical Composition.
Despite this, mica minerals are easily grouped together because of their similar atomic structure.
(Mica’s yield water when heated in a closed test tube.)

55. DIFFERENT TYPES

56. The 11 common variations are:
Biotite
Celadonite
Fuchsite
Glauconite
Lepidolite
Margarite
Muscovite
Phengite (or) Mariposite
Phlogopite
Sericite
Stilpnomelane
The many variations come from the diverse ways it formed. Mica formations are associated with volcanoes and hydrothermal vents.

57. GENERAL FORMULA X2Y4–6 Z8 O20(OH,F)4
Chemically, micas can be given the general formula
X2Y4–6 Z8 O20(OH,F)4
in which,
X is K, Na, or Ca or less commonly Ba, Rb, or Cs;
Y is Al, Mg, or Fe or less commonly Mn, Cr, Ti, Li, etc.;
Z is chiefly Si or Al, but also may include Fe3+ or Ti.

58. CHARACTERISTICS
Mica has a brilliant shininess that glitters and sparkles. In fact the name mica is believed to have come from the Latin word ‘MICARE’ which means “to shine.”
Mica is responsible for the flashes of light in composite rocks such as granite, gneiss, and slate.
The crystal structure is monoclinic with a somewhat hexagonal crystal shape. These two characteristics are due to the structure of the atoms that make up the mica group.

59. PROPERTIES Name Content Color Streak Colorless Luster
White, Yellowish, Green, Gray
Streak
Colorless
Luster
Vitreous to Pearly
Transparency
Transparent, Translucent and Opaque
Crystal System
Monoclinic
Specific Gravity
2.8
Hardness(Mohs)
2.5-3
Cleavage
Perfect

60. Fracture
Uneven
Uses
Mainly as Insulators in Electronics
Location
Mica is found in many rocks around the world. Notable deposits are found in India, South Dakota, Russia and Brazil. Larger deposits are found in Colorado(USA), Evje(Norway) and Minas Gerais(Brazil).

61. BIOTITE

62. DESCRIPTION OF BIOTITE
General Formula: K2(Mg,Fe)3 AlSi3O10(OH,O,F2)2
Biotite is a group of common rock-forming minerals forming a series between phlogopite and annite. The name is best used as a field name for dark micas for which the exact composition has not been determined.

63. DESCRIPTION OF BIOTITE – CONTD.
Biotite survives a certain amount of weathering and is found in soils, sediments and sedimentary rocks. Weathered Biotite becomes relatively brassy of bronzy in colour and has been mistaken for gold.
Its lower density, cleavage, and other properties are soon apparent to the careful observer. Finally Biotite can form as a result of hydrothermal processes, especially wall-rock alteration around ore veins.

64. OPTICAL PROPERTIES
Colour: Typically brown, brownish green or reddish brown.
Occurrence: Common in a wide range of igneous and metamorphic rocks and may be an important detrital mineral in sediments.
Cleavage: Perfect cleavage on {001}.
Twinning: Rarely visible.
Optic Orientation: Extinction is parallel or nearly parallel, with a maximum extinction angle of a few degrees. Cleavage traces are length slow.
Alteration: Alters to chlorite, clay minerals, and/or sericite, iron-titanium oxides, epidote, calcite, and sulphides
Distinguishing Features : colour, "birds-eye" extinction, nearly parallel extinction

65. BIOTITE - PHYSICAL PROPERTIES
Colour: black, dark green, dark brown
Streak: white to gray.
Lustre: vitreous.
Diaphaneity: transparent to translucent.
Cleavage: basal, perfect
Hardness: 2.5 – 3
Specific Gravity:
Chemical Classification: silicate

66. BIOTITE - USES Biotite has very limited commercial use.
Biotite particles are sometimes used as a surface treatment in decorative concrete, plaster and other construction materials.
It is also used in the potassium-argon method of dating igneous rocks.

67.  MUSCOVITE

68. OCCURRENCE
A common rock forming mineral, muscovite is found in igneous, metamorphic and detrital sedimentary rocks. 
It is not usually valuable as a mineral specimen but can be found associated with other valued minerals such as tourmaline, topaz, beryl, almandine and others.

69. MINERAL DESCRIPTION Chemical formula : KAl2(AlSi3O10)(F,OH)2
MUSCOVITE was once commonly used for windows.
The Russian mica mines that produced it gave muscovite its name (it was once widely known as "Muscovy glass").
Muscovite is a high-aluminium member of the mica family of minerals, all known for the property of perfect basal cleavage; cleavage layers can be easily peeled off into very thin sheets which are quite durable and are not easily destroyed by erosion. 
Muscovite sheets have high heat and electrical insulating properties and are used to make electrical components.

70. OPTICAL PROPERTIES Colour : colourless Composition : highly variable
Form : found as micaceous flakes or tablets with irregular outlines
Twinning : rare
Optic Orientation : parallel extinction, cleavage traces are length slow
Alteration : not generally altered
Distinguishing Features : colourless, parallel extinction, "birds-eye" extinction
Bird's eye maple, or bird's eye extinction, is a specific type of extinction exhibited by minerals of the mica group under cross polarized light (sometimes called the optical analyser). It gives the mineral a pebbly appearance as it passes into extinction.

71. SYSTEM: MONOCLINIC
Block diagram showing the relationship between the crystallographic axes and the indicatrix axes.

72. MUSCOVITE - PHYSICAL PROPERTIES
Colour : colourless, yellow, brown, green, red
Streak : white
Lustre : vitreous
Diaphaneity : transparent to translucent
Cleavage : perfect
Hardness : 2.5 – 3
Specific Gravity :
Chemical Classification : silicate

73. MUSCOVITE – USES
Muscovite has a high resistance to heat and, split into thin transparent sheets, it has been used as windows on high- temperature furnaces and ovens.
It is an insulator and was used in the past to make circuit boards.
Historically, it was used as an early window glass.

74. CALCITE

75. CALCITE - DESCRIPTION
Calcite is a rock-forming mineral with a chemical formula of CaCO3.
It is extremely common and found throughout the world in sedimentary, metamorphic and igneous rocks.
Calcite is the principal constituent of limestone and marble.
These rocks are extremely common and make up a significant portion of Earth's crust.
They serve as one of the largest carbon repositories on our planet.  

76. CALCITE - DESCRIPTION – CONTD.
The properties of calcite make it one of the most widely used minerals.
It is used as a construction material, abrasive, agricultural soil treatment, construction aggregate, pigment, pharmaceutical and more.
It has more uses than almost any other mineral. 

77. CRYSTAL SYSTEM
 The true rhombohedral unit cell, which is the acute rhombohedra, and the cleavage rhombohedron setup.
The true unit cell includes 2 CaCO3 with calcium ions at the corners of the rhombohedron and CO3 groups.
Each of which consists of a carbon ion at the centre of a planar group of oxygen atoms whose centres define an equilateral triangle.

78. CALCITE – PHYSICAL PROPERTY
Mineral class : Carbonates - Calcite group.
Cleavage : Perfect rhomboedric in three planes, subconchoidal fracture.
Hardness : 3
Density : 2.7
Colour : usually colourless, but nuances in blue, yellow, green, red, violet, even black and opaque.
Streak : White to greyish.
Lustre : Vitreous to pearly or dull.

79. USES OF CALCITE IN CONSTRUCTION
The construction industry is the primary consumer of calcite in the form of limestone and marble.
These rocks have been used as dimension stones and in mortar for thousands of years.
Limestone blocks were the primary construction material used in many of the pyramids of Egypt and Latin America.
Today, rough and polished limestone and marble are still an important material used in prestige architecture. 

80. USES OF CALCITE IN CONSTRUCTION – CONTD.
Modern construction uses calcite in the form of limestone and marble to produce cement and concrete.
These materials are easily mixed, transported and placed in the form of a slurry that will harden into a durable construction material.
Concrete is used to make buildings, highways, bridges, walls .

81. OTHER USES OF CALCITE
In a powdered form, calcite often has an extremely white colour.
Powdered calcite is often used as a white pigment or "whiting".
Some of the earliest paints were made with calcite. It is a primary ingredient in whitewash and it is used as an inert colouring ingredient of paint. 
It is softer than the stone, porcelain and plastic surfaces found in kitchens and bathrooms but more durable than dried food and other debris that people want to remove .
This is a non-flammable dust that is sprayed onto the walls and roofs of underground coal mines to reduce the amount of coal dust.

82. GYPSUM (CaSO4.2H2O)
Gypsum- a soft sulphate mineral composed of calcium sulphate di hydrate.
Gypsum was known in Old English as spærstān, "spear stone", referring to its crystalline projections.
Dehydrated gypsum is popularly known as “plaster of Paris”.
Gypsum crystals contain anion water and hydrogen bonding.

83. PROPERTIES Category Colour Cleavage Mohs scale Lustre Specific gravity
Solubility
-Sulphate minerals
-White, colorless. May be pink, brown, red due to impurities.
-Perfect on 010 distinct on 100
-1.5-2
-Vitreous to silky, pearly or waxy.
-2.31 to 2.33
-Hot, dilute Hcl

84. GYPSUM CRYSTALS

85. APPLICATIONS Used as cement blocks in building.
An ancient mortar used in building construction.
Binder in fast-dry tennis courts.
Fertilizer and soil conditioner.

86. CLAY

87. Clay- a fine grained soil.
Distinguished from other soil by size.
Formed by gradual weathering of rocks.
Absorb or lose water depending on humidity changes.
Due to absorption of water, specific gravity of clay is variable.
Divided into kaolinite, illite, vermiculite, smectite and chlorite.

88. PRODUCTION

89. USES Used in pottery, decorative and construction products.
Macaws use clay licks for survival.
Can soothe an upset stomach.
Primary ingredient in building techniques.
Kaolin clay – used as anti-diarrheal medicines.
Removal of heavy metals from waste water.

91. PROPERTIES
QUARTZ
FELSPAR GROUP
MUSCOVITE
BIOTITE
MICA
GYPSUM
CRYSTAL SYSTEM
Hexagonal
Monoclinic and Triclinic
Monoclinic
Category of sulphate
COLOUR
Colourless when pure; red, green, blue
Grey, green, blue, pink and white
White to Colourless
Greenish to brown or black; even yellow
White, yellowish, green, grey
White, colourless
HARDNESS 7
6 – 6.5
2 – 2.5
SPECIFIC GRAVITY
2.65 – 2.66
2.54 – 2.57
2.7 – 3.1
2.8
2.31 – 2.33
CLEAVAGE
Generally absent
Perfect
Highly perfect basal cleavage
LUSTRE
Vitreous

92. PROPERTIES
AMPHIBOLE MINERALS
CALCITE
CRYSTAL SYSTEM
Monoclinic
Crystalline, granular, rhombohedra
COLOUR
White to light grey
White or colourless; also grey, yellow & green
HARDNESS
5.5 – 6 3
SPECIFIC GRAVITY
2.71
CLEAVAGE
Perfect
Perfect with 74’
LUSTRE
Vitreous