Done, your profile is created.Finish your profile by filling in the following fields
Forgot Password Earn Money,Free Notes
Password sent to your Email Id, Please Check your Mail
Updating Cart........ Please Wait........
What is a Mineral?
What is a Mineral?
What is a Mineral
solid that has
structure Formation Composition
• 2500 kinds of
some are easy
to find and
• Mineral Properties
Each type of mineral has its own combination of properties that identify it.
Some of the properties are
Many minerals come in a wide variety of colors. Different minerals can be
the same color. It is difficult to use just color to identify a mineral.
Streak is the color of a mineral in powdered form. You can see a mineral’s streak
by rubbing a sample across an unglazed ceramic plate and observing the powder
left behind. Sometimes a mineral’s streak is very different from the color of the
Hardness is the resistance of a mineral to scratching. Geologists use the
Mohs' hardness scale to seriate and compare mineral hardness.
Specific gravity is the ratio of the weight of a given volume of a mineral to the
weight of an equal volume of water. Higher specific gravity means the mineral
Cleavage is how a mineral breaks. Some minerals break in smooth, flat
surfaces at identifiable angles, such as calcite. Others fracture and produce
no flat surfaces, such as quartz.
Fracture is how a mineral breaks when no cleavage surfaces form. For
example, quartz breaks in a pattern known as conchoidal fracture.
Conchoidal fracture looks like smooth, curved surfaces.
Luster is how a mineral reflects light or how it shines. Some ways to
describe luster include glassy or vitreous, metallic, dull, and pearly. Crystal form
Crystal form describes the geometric shape of a
crystal. There are seven main groups of crystal
shapes, including cubic, hexagonal, and tetrahedral.
Transparency describes how a mineral transmits light.
Some minerals are transparent (you can see through
them); others are translucent (some light passes through
a sample) or opaque (no light passes through a sample).
Magnetism is a special property of some minerals,
especially magnetite. Samples are attracted by a
magnet. Lodestone, a special form of magnetite, is a
Reaction to acid
Some minerals react to acid. Calcite especially will fizz
and bubble when it comes in contact with an acid such
as hydrochloric acid at room temperature.
used to identify
– Color always a
reliable way to
– However, color can
change do to
and cold Types
• Idiochromatics:Fairly constant colour(Copper Group of
• Allochromatic: Variable colour due to
impurities(Mineral Like Quartz, Calcite, Fluorite)
• Pseudochromatic: Showing a false colour Simultaneous
reflection and refraction(Diamond)
• The way a
• mineral reflects
• light from
• its surface
– Don’t have much of a
reflection; known as
glassy, pearly, and dull Factors affects Lustre
` The refractive index of a mineral
• The absorption (of light) capacity of a
• The nature of reflecting surface
Metallic: Shine resembles as of MetalsGalena
Vitreous: Lustre of GlassQuartz
Pearly: Shine resembles as of Pearl Labradorite
Silky: Shine resembles as of Pure silkGypsum
Resinous: oily shine, waxy or greasyNepheline
Dull: Shine is almost absentChalk. Clay , Bauxite
• Color of powder
scraped off when it
is rubbed against
• a hard, rough
• Streak may be a
than the mineral
itself. Streak: colour of the fine powdered
Determined by using a streak plate
Magnetite and chromite are almost black in
colour where as streak of magnetite is black and
that of Magnetite is brown
• The ability to resist
• Most useful properties
for identifying a mineral
• Numbered 110.
• Describe how the mineral
breaks along flat surfaces. Ex:
• Most minerals break along a
rough or jagged surface. Ex:
• Even: Broken srface is • woody
Uneven: Broken surface Hackly:Irregular sharp
is irregular surface Native
• Conchoidal: Broken • Earthy: Surface is
surface is having smooth and soft and
concentric rings with porousChalk
(Behaviour towards Break, bend, cut or
• Sectile: Cut with a knife
• Malleable: Can be flattened by a hammer
• Brittleness: Change to fine grain or
powder under a knife or a hammer
• Minerals have a
crystal shape that
results from the way
the atoms or
together as the
mineral is forming
Structure of a Mineral
(Physical make up of a mineral)
• Tabular: Mineral in the form of flattened, square,
rectangle (Calcite, orthoclase, barite)
• Elongated: Mineral is in the form of a thin or
thick elongated, columnlike crystals. (Beryl,
• Bladed: Mineral appears to be composed of thin,
flat , bladed like overlapping. (Kyanite)
• Lamellar: Mineral made up of relatively thick,
flexible, leaflike sheets.(Vermiculite)
• Foliated: similar to lamellar in boarder sense but
individual sheets are thin. (Muscovite)
• Fibrous: Mineral composed of Fibres, generally
separable easily or with a little difficulty. (Asbestos
• Radiated: needle like crystal appears to originating
from a common point. (iron pyrite)
• Granular: densely packed mass of small crystal
• Globular: Botroiydal, rounded, bulblike overlapping,
• Reniform: Globular similar to human kidney shape(H)
• Mammillary: Globular form, conspicuous overlapping
with each other(malachite)
• Magnetite: Naturally
Smells like rotten eggs
13.3: Uses of Minerals
• Minerals are raw
materials used for
a wide variety of
dyes to dishes and
from table salt to
Alpha Quartz or High Quartz (describes
Physical Properties of
Quartz stable at normal room conditions
Environment : develops in a wide variety of
environments, igneous, metamorphic,
Hardness: 7.0 on Moh's
Scale Index of refraction:
Transparency: Transparent to opaque
Luster: Most specimens have a vitreous
luster; Some yellow or brown are resinous;
0.009 Streak: White
Earthy specimens are dull; Very rare varieties
Spec. Grav.: 2.5 2.7
have an adamantine luster
Other Marks for identification purposes:
(prisms, pyramidal) Many specimens fluoresce; All specimens are
triboluminescent and piezoelectric
Striking Features: Hardness, crystal forms,
Cleavage : none
striations on crystal faces, and frequent
appearance of conchoidal fractures on
In Group: Silicates;
Complex Tests: Dissolves in hydrofluoric acid
Tectosiliates; Silica Group:
Distinguishing from Similar Minerals: Beryl is
or as an oxide by a few
harder (7½ 8), without the horizontal
striations of Quartz; Feldspar is a softer stone
Other Names: Silica (6), with perfect cleavage; Calcite is very soft
Typical Cutting StylesFaceted, cabochons
Quartz, Chalcedony, and Opal)
Varieties of Quartz
Other than Clear Quartz, Quartz occurs as
Amethyst, Aventurine, Citrine, Carnelian,
Herkimer Diamonds, Jasper, Onyx, Rose
Quartz, Rutilated Quartz, Smoky Quartz and
Tourmalinated Herkimer Diamonds are
Quartz crystals with double terminations and
Tourmalinated Quartz contains hairs of
Tourmaline crystals, but both are minor
Quartz family members.
Comments: Purplecolored druse of amethystine quartz and white
calcite. Location: Rio Grande do Sul, Brazil. Scale: Sample size 20
Comments: Wellformed crystals of chalcopyrite and quartz.
Location: Boldut mine, 61 level (350 meters deep), Cavnic,
Maramures, Rumania. Scale: 5.5 x 3.5 cm.
Comments: Black, prismatic ilvaite with quartz.
Location: First Sovietskij mine, Dalnjegorsk, Russia. Scale: 3.5 x 4.5
Comments: Crystal druse of transparent quartz crystals.
Location: Hot Springs, Arkansas, USA. Scale: Specimen size 6 cm.
Comments: Purple crystal of fluorapatite on slightly smoky quartz crystals. Former Dr. E.E. David and
Houston Museum collections.
Location: Pech, Kunar Province, Nuristan, Afghanistan. Scale: Crystal size 3.0 x 2.1 x 1.7 cm.
Comments: White epistilbite cluster 25 mm across on amethyst quartz crystal matrix.
Location: Sawda, Jalgaon, Maharashtra, India. Scale: 10x8x5 cm.
Comments: Slightly smokey quartz overgrown with rose quartz. Note the exceptional
transparency of the rose quartz.
Location: Lavra da Ilha, Taquaral, Minas Gerais, Brazil. Scale: 10 cm by 5.2 cm.
• KAlSi O
Orthoclase KAlSi O
NaAlSi O CaAl Si O Plagioclase
3 8 2 2 8
In the manufacture of highclass,
glass, feldspar should have a maximum of
0.1 Fe O though upto 0.3 is
Orthoclase usually light colored white, pink, yellow, or
cream, and not transparent. The gem variety is clear to
pale yellow, and some called "noble orthoclase"
Microcline white, pink, pale yellow, or sometimes
greenblue, and not transparent. The greenblue variety
is called "amazonite"
Plagioclase gray to grayishwhite is common, but may
also be white, pink or pale yellow. More semi opaque
than the other feldspars on average, and contains
striations on some crystal faces or cleavage surfaces.
The feldspars make up the major constituent of many
igneous and metamorphic rocks, they form at medium to
high temperature and at some depth. Microcline can
form in granite pegmatites and at lower temperatures.
• Luster: vitreous to semi vitreous.
• Sp. Gravity:2.562.58
• Cleavage: 2sets
• Varities: Adularia transparent varieties.
» Sanidine ahigh temperature variety(stable over 900 ˚C)
• Composition: K Al Si O
• Potash feldspar:
» Albite labradorite
» Oligoclase Bytwonite
» Andesine anorthite
Albiteanorthite Feldspar is generally used for three purposes
In making the body composition of several
types of procelain, china and earthenware
and also in the preparation of glazes and
enamel. As an important ingredient in the
glass sand batch.
As a bonding agent in the manufacture
of bonded abrasives like wheels and
discs of garnet, corundum, emery etc.
The glass and ceramic industries are the
major consumers of feldspar and account for
95 of the total consumption.
Feldspar is used in varying proportions in porcelain,
china and earthenware. Earthenware contains on an
average 12 feldspar
25 ball clay
This proportion of feldspar varies in different products
like Wall tile 5
Floor tile 30
Sanitary china and prodelain bodies 30