Mineralogy -II

Rock Forming Minerals
• Only few minerals form the great bulk of the
rock of the crust of the earth. These very
common minerals have been grouped to-
geather as rock forming minerals.
• Among the rock forming minerals, Three
groups like Silicates, Oxides and Carbonates
are considered as these three groups include
most of the common rock forming minerals.

The Silicate Group
• About eight percent of the crest of the earth is
made of silicates and free silica. Among the silicate
group, the total number of minerals known to
occur in nature may easily approach to about one
thousand species. Since majority of them are quite
rare in occurrence. Since this group of minerals is
one of the biggest a little knowledge of the
important aspect of the group such as Chemical
Composition, Atomic Structure, Classification and
descriptive study of some important minerals.

The Silicate Group
Chemical Composition
• Most common silicate minerals are made up
chiefly of a few of the following nine elements,
Na, K, Al, Ca, Mg, Fe, Li, Si, and O. Other
elements are present only rarely and in traces.

The Silicate Group
Atomic Structure
• The fundamental unit. All silicates are simple or complex
repetition of a fundamental Silicon-Oxygen Tetrahedron,
represented by the formula [ SiO 4] 4-. In this tetrahedron,
the very small Si 4- ion is situated in the centre and is
surrounded on the four sides by relatively big oxygen ions.
The dimensions. The dimension of this unit cell of silicon-
oxygen tetrahedron are constant. Further, the distance
between the silicon ion at the centre and the oxygen atom at
the corner is 106 A0 . This fundamental unit is repeated,
linked and joined in different ways giving rise to different
types of silicate structures.

The Silicate Group
Independent Tetrahydra.
A unit SiO4 has four negative charges. Hence it has
the capacity to exist as an isolated or independent
tetrahydron provided these four negative charges
are balanced by four positive ions of other metals.
This actually happens in nature in orthosilicates.
Sometimes more than one elements may combine
with an independent tetrahydon to satisfy the four
negative valency giving rise to different types of
minerals.

The Silicate Group
Double Linked Tetrahedra
• In Some cases SiO4- may first get linked together in
such a way that one oxygen atom is held common
between the two cells. The net negative charge left
in two joint tetrahedral is 6 (O-Si-O-Si-O) and the
formula for such tetrahydron is (Si2O7)6-. In fact it
is known as Si2O7 group.
Complexed-linked Tetrahedron.
• In some cases, three, four and six tethedron may
be linked together in such a way that they form
closed ring-type structures.

The Silicate Group
The Chain Structure
• It results from single-dimensional continuation in which each
tetrahedron is linked to the adjacent tetrahedron by sharing the two
corners. This is the characteristic structure of Pyroxene group of
silicates and is commonly referred as single-chain structure.
• A double chain structure is also possible according to formula
• [ Si4 O11]6- The amphibole group of minerals has this type of double-
chain extension.
• These will have six, eight and twelve free negative charges to be satisfied
• The formula is expressed as
• [Si3O9]6-, [Si4O12]8-, and [ Si6O18]12-
• Repetition in space The single tetrahedron and the double linked
tetrahedron as described above may in themselves be repeted in space
in a variety of ways giving rise to different structural forms in the silicate
minerals.

The Silicate Group
The Sheet Structure
• A two-dimensional continuation of silicon
tetrahedron commonly result in a layered or sheet
structure. It is characterized by linking of the
tetrahedrons in such a way that all the three apexes
of one tetrahedron are linked with an adjoining
tetrahedron resulting ultimately into hexagonal
pattern lengthwise, and breadthwise.
• Such sheets may be linked with other identical
sheets resting above or below through metallic ions
resulting in a considerable weaker bond.

The Silicate Group
The Network Structure
• In this type of structure, the silicon- oxygen
tetrahedron are so arranged that they form a
three dimensional network.

The Felspar Group
• The felspar group are the most prominent
group of minerals making more than fifty
percent by weight, crust of the earth up to a
depth of 30 km. These occur chiefly in the
igneous rocks but also form a good proportion
of their metamorphic derivatives.

The Felspar Group
• In Chemical Composition, felspar are chiefly
aluminosilicates of Na, K and Ca with the chemical
formula:
• WZ4O8
• In which W= Na, K, Ca and Ba
• And Z= Si and Al
• The Si:Al shows variation from 3:1 to 1:1. Some
examples of minerals are
• NaAlSi3O8
• KalSiO3O8
• CaAl2SiO2O8

The Felspar Group
Atomic Structure
• At atomic level, the felspars shows a continuous
three-dimensional network type of structure in
which the SiO4 tetrahedra are linked at all four
corners, each oxygen ion being shared by two
adjacent tetrahedron
• The resulting network is negatively charged and
these negative charges are satisfied by the presence
of positively charged K, Na, Ca and also Ba.

The Felspar Group
Orthoclase
Plagioclase
K-feldspar
Ca/Na-feldspar

The Felspar Group
Crystallization
• The felspar group of minerals crystallographic
systems: monoclynic and triclinic.
• Infact the plagioclase of felspar crystallizes only
in Triclinic system.

The Felspar Group
Felspar are classified both as on the basis of their chemical
composition and also on their mode of crystallization.
Chemically felspar group fall into two main group the potash felspar
and soda lime felspar
Potash Felspar
• Orthoclase
• Sandine
• Microline
Soda lime Felspar
• Albite
• Labradorite
• Oligoclase
• Bywonite
• Andesine
• Anorthite

The Felspar Group
Physical Properties
• In addition to their close relationship in chemical
composition, crystallography and atomic
constitution, felspar group of minerals exhibit a
broadly similarity and closeness in their physical
character as well so that differentiation of one
variety from other requires very through,
sometimes microscopic examination.
• They are general light in color, have lower specific
gravity and have a double cleavage and a hardness
varying between 6-6.5.

Orthoclase
Physical Properties of Orthoclase
• Cleavage: {001} Perfect, {010} Good
• Color: Colourless, Greenish, Greyish yellow, White, Pink.
• Density: 2.56
• Diaphaneity: Transparent to Translucent
• Fracture: Uneven - Flat surfaces (not cleavage) fractured in an uneven
pattern.
• Habit: Blocky - Crystal shape tends to be equant (e.g. feldspars).
• Habit: Massive - Granular - Common texture observed in granite and
other igneous rock.
• Habit: Prismatic - Crystals Shaped like Slender Prisms (e.g.
tourmaline).
• Hardness: 6 – Orthoclase
• Luminescence: Non-fluorescent.
• Lustre: Vitreous (Glassy)
• Streak: White

Microcline
Physical Properties of Microcline
• Color: Bluish green, Green, Gray, Greyish yellow, Yellowish.
• Density: 2.56
• Diaphaneity: Translucent to transparent
pattern.
• Habit: Crystalline - Coarse - Occurs as well-formed coarse sized
crystals.
• Habit: Prismatic - Crystals Shaped like Slender Prisms (e.g.
tourmaline).
• Luminescence: Fluorescent, Short UV=cherry red.
• Streak: White

Albite
Physical Properties of Albite
• Color: White, Gray, Greenish gray, Bluish green, Gray.
• Density: 2.61 - 2.63, Average = 2.62
• Diaphaneity: Transparent to translucent to sub translucent
pattern.
• Habit: Granular - Generally occurs as anhedral to subhedral crystals in
matrix.
• Habit: Striated - Parallel lines on crystal surface or cleavage face.
• Hardness: 7 - Quartz
• Luminescence: Fluorescent, Short UV=herry-red blue, Long UV=white.
• Streak: White

Anorthite
Physical Properties of Anorthite
• Color: Colourless, Gray, White, Red, Reddish gray.
• Density: 2.72 - 2.75, Average = 2.73
• Diaphaneity: Transparent to Sub transparent to translucent
pattern.
• Habit: Euhedral Crystals - Occurs as well-formed crystals showing
good external form.
• Habit: Granular - Generally occurs as anhedral to subhedral crystals
in matrix.
• Habit: Striated - Parallel lines on crystal surface or cleavage face.
• Streak: White

The Felspar Group
• Crystographically, Felspar fall into two crystal
systems
Monoclinic Felspar
• Orthoclase
• Sandine
Triclinic Felspar
• Microclinic
• Albite-Anorthite

Pyroxene Group
• The pyroxene group of minerals forms another
set of important rock-forming minerals. They
occur in good abundance in the dark colored
igneous and metamorphic rocks. In fact among
the ferro-magnesium minerals, pyroxenes
occupy first place as rock forming group.

Pyroxene Group
• In Chemical Composition, Pyroxenes are
essentially ferro-mangnesium silicates, with
other bases as calcium, sodium, aluminum and
lithium being also present in varying amount in
different varieties.
• In the simplest form, the chemical composition
of pyroxenes may be represented as RSiO3 with
R representing Ca, Na and Al and li etc.

Pyroxene Group
Atomic Structure
• The pyroxene show the single-chain structure
of silicates. In this type of constitution, the
fundamental silicon-oxygen tetrahedron are
linked together at one of the oxygen atoms. In
other words, one oxygen atom is shared
between two adjacent SiO4 giving rise to typical
prismatic cleavage of the group.

Pyroxene Group
Crystallization
• Pyroxenes in two systems: Orthorhombic and
Monoclinic. The prism angle in pyroxenes are
870 and 930 and form a distinct features of
Pyroxenes.

Pyroxene Group
• Pyroxenes care commonly classified on the basis of their
crystallization in two groups
• Orthorhombic Pyroxenes
• Enstatite
• Hyperstene
• Monoclinic Pyroxenes
• Clinoenstatite
• Clinohypersthene
• Diopside
• Augite
• Acmite
• Spodumene

Pyroxene Group
Physical Properties
• They are generally dark in color, their hardness
varies between 5 to 6 and sp gravity from 3 to
3.3. Pyroxene crystal are generally short and
stout.

Enstatite
Physical Properties of Enstatite
• Cleavage: { 110} Distinct, {010} Distinct
• Color: White, Yellowish green, Brown, Greenish white, Gray.
• Density: 3.1 - 3.3, Average = 3.2
• Diaphaneity: Translucent to opaque
• Fracture: Brittle - Generally displayed by glasses and most non-metallic
minerals.
• Habit: Lamellar - Thin laminate producing a lamellar structure.
• Habit: Massive - Fibrous - Distinctly fibrous fine-grained forms.
• Hardness: 5.5 - Knife Blade
• Lustre: Vitreous - Pearly
• Streak: Gray

Hypersthene
Physical Properties of Hypersthene
• Cleavage:{100} Perfect, {010} Perfect
• Color: Greyish white, Greenish white, Yellowish white, Bronzy brown,
Greyish black.
• Density:3.2 - 3.9, Average = 3.55
pattern.
• Habit: Crystalline - Coarse - Occurs as well-formed coarse sized crystals.
• Habit: Massive - Granular - Common texture observed in granite and other
igneous rock.
• Hardness:5.5-6 - Knife Blade-Orthoclase
• Luminescence:Non-fluorescent.
• Luster:Vitreous - Silky
• Streak:grayish greenish white

Diopside
Physical Properties of Diopside
• Cleavage: {110} Good, Indistinct
• Color: Blue, Brown, Colourless, Green, Gray.
• Density: 3.25 - 3.55, Average = 3.4
• Diaphaneity: Transparent to translucent
• Fracture: Brittle - Conchoidal - Very brittle fracture producing small,
conchoidal fragments.
• Habit:Granular - Generally occurs as anhedral to subhedral crystals in matrix.
• Habit: Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).
• Hardness: 6 - Orthoclase
• Streak: White green

Augite
• Physical Properties of Augite
• Cleavage: {110} Perfect, {010} Indistinct
• Color: Brown green, Green, Light brown, Dark brown, Black.
• Density: 3.2 - 3.6, Average = 3.4
• Diaphaneity: Translucent to opaque
• Habit: Columnar - Forms columns
• Habit: Granular - Generally occurs as anhedral to subhedral crystals in
matrix.
• Hardness: 5-6.5
• Lustre: Vitreous - Resinous
• Streak: Greenish gray

Amphibole Group
• This group of minerals is regarded as a parallel
to the pyroxene group because most minerals
of this group shows a striking resemblance to
the pyroxene minerals in many of their
properties. They are also characterized with a
double cleavage, a hardness between 5-6 and sp
gravity from 3 to 3.5 they are generally dark in
color.

Amphibole Group
• Amphibole minerals are also metasilicates with Si :
O ratio of 4: 11. The Metallic ions present in
amphiboles in amphiboles are Ca, Mg, Fe and
sometimes Mn, Na , K and H. Presence of (OH)
ion, which may be replaced by F and Cl, is another
peculiarly of chemical composition. The general
chemicals formula:
• [Si4 O11]2 [OH]2, forms the basis for combination
with the metallic ions. There is possibility of a
good degree of substitution between various ion
such as Al, Mg, Fe, Ca, Na and K, H and F and So
on giving rise to a variety of amphibole minerals.

Amphibole Group
Atomic Structure
• There is a basic difference in the atomic
constitution of pyroxenes and amphiboles the
SiO4 tetrahedra are linked in double chain; it is
for this reason that the amphiboles are more
complex in their chemical constitution.

Amphibole Group
Crystallization
• More important members of amphiboles group
crystallize in two crystal system
• Orthorhombic and Monoclinic The amphibole
crystal are generally long, slender and prismatic;
these sometimes fibrous in habit, the prism
angle in amphibole is 124 0

Amphibole Group
• Amphiboles are commonly divided in two
groups on the basis of their crystallization
• Orthorhombic amphiboles and monoclinic
amphiboles.

Amphibole Group
• Despite wide variation in their chemical
composition, amphiboles show quite few common
physical characters due to their atomic structures.
Thus all of them crystallize in only two crystal
systems.
• Physical Properties
• Most of them are dark in color have a hardness
ranging between 5-6 and Sp Gr. Between 2.8 to
3.6. Their crystal are elongated, slender and often
fibrous in nature.

Anthophyllite
• Physical Properties of Anthophyllite
• Cleavage: {110} Perfect, Distinct, Distinct
• Color: White, Greenish gray, Green, Clove brown, Brownish green.
• Density: 2.85 - 3.57, Average = 3.21
• Fracture: Conchoidal - Fractures developed in brittle materials
characterized by smoothly curving surfaces, (e.g. quartz).
• Habit: Fibrous - Crystals made up of fibers.
• Habit: Massive - Uniformly indistinguishable crystals forming large
masses.
• Hardness: 5-6 - Between Apatite and Orthoclase
• Luminescence: Fluorescent, Short UV=red, Long UV=red.
• Streak: Gray

Tremolite
Physical Properties of Tremolite
• Cleavage:{110} Perfect, {010} Distinct
• Color: Brown, Colourless, Gray, White, Light green.
• Density:2 .9 - 3.2, Average = 3.05
• Fracture: Sub Conchoidal - Fractures developed in brittle materials
characterized by semi-curving surfaces.
• Habit: Columnar - Forms columns
• Habit: Massive - Granular - Common texture observed in granite and
other igneous rock.
• Hardness: 5-6 - Between Apatite and Orthoclase
• Luminescence: Fluorescent, Short UV=yellow, Long UV=range
pink.
• Streak: White

Actinolite
Physical Properties of Actinolite
• Cleavage: {110} Perfect, {110} Perfect
• Color: Green, Green black, Gray green, Black.
• Density: 2.98 - 3.1, Average = 3.04
• Fracture: Splintery - Thin, elongated fractures produced by
intersecting good cleavages or partings (e.g. hornblende).
• Habit: Bladed - Aggregates of thin lath-like crystals (e.g. kyanite).
• Habit: Fibrous - Crystals made up of fibers.
• Habit: Radial - Crystals radiate from a center without producing
stellar forms (e.g. stibnite)
• Hardness: 5.5 - Knife Blade
• Streak: White

Hornblende
• Physical Properties of Hornblende
• Color usually black, dark green, dark brown
• Streak white, colourless
(brittle, often leaves cleavage debris behind instead of a
streak)
• Lustre vitreous
• Diaphaneity translucent to nearly opaque
• Cleavage two directions intersecting at 124 and 56 degrees
• Mohs Hardness 5 – 6
• Specific Gravity 2.9 - 3.5
(varies depending upon composition)
• Diagnostic Characteristics Cleavage, color, elongate habit
• Crystal System monoclinic

Mica Group
• Minerals of Mica Group are characterized with the
presence of a micaeous structure (Cleavage) by virtue of
which these can be split into very thin sheets along one
direction. This micaceous cleavages is explained by their
atomic constitution they consist of SiO4 tetrahedra
linked at three of their corner and extending in two
dimensions. This is called Sheet structures.
• Micas are besides feldspar, pyroxenes and amphiboles,
very common rock forming minerals forming
approximately 4 % of the crest of the earth.

Mica Group
• Mica group of minerals show a great variation in
their chemical composition. Broadly speaking they
are mainly silicates of aluminum and potassium
containing one or more of
• Hydroxyl group
• Sodium
• Magnesium
• Lithium
• Iron
• Fluorine

Mica Group
Atomic Structure
• As mentioned above, micas are characterized
with sheet structure in atomic constitution. In
this type of structure, the basic unit of silicates,
SiO4 tetra hydra lined at all their three corners
resulting in Si :O ratio of 2:5 Such a linkage
when extended in two directions results in
Sheet of SiO2-tetrahedra.

Mica Group
Crystallization
• Most important member of mica Group
crystallize in one system only: Monoclinic
System some less important members
crystallize in Triclinic System.

Mica Group
• Micas are generally divided into two group based
on their chemical composition
Light Micas
• Muscovite
• Paragonite
• Lepidolite
Dark Micas
• Biotite
• Phlogopite
• Zinwaldite

Mica Group
Physical Properties
• Among the properties that are common to all
the minerals of the mica group are
• Perfect basal cleavage
• Low hardness between 2-3
• Viterous lusture
• Platy habit of the crystal

Muscovite
Physical Properties of Muscovite
• Cleavage:{001} Perfect
• Color:White, Gray, Silver white, Brownish white, Greenish white.
• Density:2.77 - 2.88, Average = 2.82
• Diaphaneity:Transparent to translucent
• Fracture:Brittle - Sectile - Brittle fracture with slightly sectile shavings
possible.
• Habit:Foliated - Two dimensional platy forms.
• Habit: Massive - Lamellar - Distinctly foliated fine-grained forms.
• Habit:Micaceous - Platy texture with "flexible" plates.
• Hardness:2-2.5 - Gypsum-Finger Nail
• Luminescence:Non-fluorescent.
• Luster:Vitreous (Glassy)
• Streak:white

Biotite
Physical Properties of Biotite
• Cleavage: {001} Perfect
• Color: Dark brown, Greenish brown, Blackish brown, Yellow, White.
• Density:2.8 - 3.4, Average = 3.09
• Diaphaneity: Transparent to translucent to opaque
pattern.
• Habit: Micaceous - Platy texture with "flexible" plates.
• Habit: Pseudo Hexagonal - Crystals show a hexagonal outline.
• Hardness: 2.5-3 - Finger Nail-Calcite
• Streak: Gray

Oxide Minerals
• Next to silicate minerals, oxide occupy an
important positions in the list of rock forming
minerals. Some of them are important as non-
metallic refrectory minerals (e.g. Quartz,
coroundum, spinel, and rutile) Many others are
very important as Source minerals of metals
such as hematite, magnetite(iron), cuperite
(copper), Zincite (zinc), cassiterite (tin) and
bauxite (aluminum).

Oxide Minerals
Quartz (SiO2)
• Polymorphous Transformation (Polymorphism is the ability
of a solid material to exist in more than one form or crystal
structure.)
• Quartz, when heated, transforms into high temperature
modified as follows
• Quartz ------ Tridymite ------ Critobalite -------- Melt
• The variety named as Quartz itself as two polymorphs
• α Quartz
• β Quartz
• Identification of exact type of minerals requires through
investigation of the mode of formation.
870 0C 1470 0C 1713 0C

Oxide Minerals
• Right handed and left handed Quartz
• When occurring in distinct crystal, quartz may be
distinguished into right handed and left handed
types This is done on the basis of recognition of
some typical faces such as trigonal, trapezohedron
and dipyramid. This two faces normally occur at
the edges of prism faces, one above 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 crystal.

Right handed and left handed Quartz

Oxide Minerals
Coloured Varieties
• Common pure quartz is a colorless transparent
mineral. Presence of even a trace of an impurity
may give it a characteristics color and hence a
variety. A few common types of quartz are
• Amethyst: Purple or White
• Smoky : Dark to light brown, even black
• Milky: Pure white or opaque
• Rose Red: Coloured is attributed to presence of
titanium.

Oxide Minerals
Crystocrystalline Types
• In many cases, crystallization of pure silica to quartz remains
incomplete due to interruption in the process for one reason
to another. Silica occurring in this cryptocrystalline varieties,
altogether close in composition and physical properties to
quartz is named directly.
• A few variety of cryptocrystalline silica are
• Chalcedony, Agate, Onyx, Flint, Jasper
• Occurrence Quartz and its variety occur in all types of rocks;
Igneous, sedimentary and metamorphic. In igneous rocks,
quartz makes up the bulk of acidic varieties. In sedimentary
rocks quartz makes up sandstone and ortho quartzite. Loose
sand consists mostly of quartz grains. The metamorphic
rocks like gneisses and schists contain good proportion of
quartz in some cases.

Quartz
Physical Properties of Quartz
• Cleavage: {0110} Indistinct
• Color: Brown, Colourless, Violet, Gray, Yellow.
• Density: 2.6 - 2.65, Average = 2.62
• Diaphaneity: Transparent
• Fracture: Conchoidal - Fractures developed in brittle materials characterized
by smoothly curving surfaces, (e.g. quartz).
• Habit: Crystalline - Fine - Occurs as well-formed fine sized crystals.
• Habit: Druse - Crystal growth in a cavity which results in numerous crystal
tipped surfaces.
• Hardness: 7 - Quartz
• Luminescence: Fluorescent and Triboluminescent, Short UV=yellow-
orange, Long UV=yellow-orange.
• Streak: white

Corundum
Physical Properties of Corundum
• Cleavage: None
• Color: Blue, Red, Yellow, Brown, Gray.
• Density: 4 - 4.1, Average = 4.05
• Fracture: Tough - Difficult to break apart as shown by fibrous minerals and
most metals.
• Habit: Euhedral Crystals - Occurs as well-formed crystals showing good
external form.
• Habit: Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).
• Habit: Tabular - Form dimensions are thin in one direction.
• Hardness: 9 – Corundum
• Luminescence: Sometimes Fluorescent, Long UV=red.
• Magnetism: Nonmagnetic
• Streak: none

Spinel
Physical Properties of Spinel
• Cleavage: None
• Color: Colourless, Red, Blue, Green, Brown.
• Density: 3.57 - 3.72, Average = 3.64
pattern.
• Habit: Euhedral Crystals - Occurs as well-formed crystals showing good
external form.
• Habit: Massive - Granular - Common texture observed in granite and other
igneous rock.
• Hardness: 8 - Topaz
• Luminescence: Sometimes Fluorescent, Short UV=red, Long UV=red.
• Magnetism: Nonmagnetic
• Streak: greyish white

Carbonate Minerals
• A few carbonate minerals are very important as
rock forming minerals in sedimentary and
metamorphic groups. These include calcite,
dolomite and magnetite.

Carbonate Minerals
Calcite-Dolomite

Calcite
Physical Properties of Calcite
• Cleavage: {1011} Perfect, {1011} Perfect, {1011} Perfect
• Color: Colourless, White, Pink, Yellow, Brown.
• Density:2.71
• Habit: Massive - Uniformly indistinguishable crystals forming large masses.
• Habit: Stalactitic - Shaped like pendant columns as stalactites or stalagmites
(e.g. calcite).
• Hardness: 3 - Calcite
• Luminescence: Fluorescent and phosphorescent, Short UV=yellow, blue,
red green, Long UV=yellow, blue, red green.
• Streak: white

Calcite
Physical Properties of Dolomite
• Cleavage: { 1011} Perfect, {1011} Perfect, {1011} Perfect
• Color: White, Gray, Reddish white, Brownish white, Gray.
• Density: 2.8 - 2.9, Average = 2.84
• Habit: Blocky - Rhombohedral - Crystal shape resembles rhomohedrons.
• Habit: Massive - Uniformly indistinguishable crystals forming large masses.
• Hardness: 3.5-4 - Copper Penny-Fluorite
• Streak: white

Magnesite
• Physical Properties of Magnesite
• Cleavage: {1011} Perfect, {1011} Perfect, {1011} Perfect
• Color: Colourless, White, Greyish white, Yellowish white, Brownish white.
• Density: 3
• Fracture: Brittle - Conchoidal - Very brittle fracture producing small, conchoidal
fragments.
• Habit: Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g.
howlite).
• Habit: Massive - Fibrous - Distinctly fibrous fine-grained forms. Habit: Massive -
Granular - Common texture observed in granite and other igneous rock.
• Hardness: 4 - Fluorite
• Luminescence: Fluorescent, Short UV=blue white, Long UV=bright blue white.
• Streak: White

• Engineering and General Geology :by Parbin Singh
• Textbook of Engineering Geology :N.Chenna Kesavullu
• http://geology.com/
• http://webmineral.com/
• http://www.mindat.org/
• http://www.asu.edu/courses/glg103/PDF%20labs/Lab%202%20Mineral%20L
ab%20ID%20revised%2017JULY2010.pdf

Mineralogy -II

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