PYROXENE MINERAL GROUP.pptx

PYROXENE MINERAL GROUP
Name-Ranjeet Biswal
Roll No-22GEOL-027
Class-M.Sc 1st year

CONTENTS:
CLASSIFICATION
SILICATE STRUCTURE
PHYSICAL PROPERTIES
USES
CONCLUSION
INTRODUCTION
GENERAL FORMULA
MODE OF OCCURRENCE
OPTICAL PROPERTIES

 INDRODUCTION
Mineral- A mineral is a naturally
occurring homogenous
substance which has a more or
less definite chemical
composition and definite
atomic structure. The minerals
are usually formed by inorganic
processes.
Example-quartz,feldspar,olivine
and calcite .

(Fig-Most abundants mineral in
earth’s crust.)
 Pyroxene - The name pyroxene is derived from
Greek words which means stranger to fire.
Pyroxene was named because of its presence
in glassy or vitreous lava.
 Pyroxene are constitute 11% of earth
crust materials and hold’s 4th position in
abundance after plagioclase feldspar,
alkali feldspar and quartz.
 Pyro - Fire
 Xenos - Stranger

 Pyroxene are generally formed
during early stage of magmatic
period , when the temperature is
very high . So therefore it have
high density.
 It is formed after the formation
of olivine.
 It is belong to discontinuous
crystallization series.
 Pyroxene is mafic mineral .
 Pyroxene is very susceptible to
chemical and physical
weathering.
 BOWEN’S REACTION SERIES

 GENERAL FORMULA
 Here X represents ions of larger size, such as
calcium(Ca),sodium(Na),iron(Fe) and magnesium(Mg).
X Y ( SI2O6 )
 Y represents ions of smaller size, such as
chromium(Cr),aluminium(Al),magnesium(Mg),manganese(Mn) and
cobalt(Co).

 CLASSIFICATION
 Pyroxene is divided into two main group based crystal
structure and chemical composition.
 ORTHOPYROXENE- Pyroxene that crystallize in the
orthorhombic crystal structure .
 Example- Enstatite,Ferrosilite and
Hyperthene .
(Fig- Enstatite )
(Fig – Diopside)
 CLINOPYROXENE- Pyroxene that
crystallize in monoclinic crystal structure
.
 Example-Diopside,Hedenbergite and
Augite .

(Fig-Ternary diagram)
 The figure shows wollastonite,enstatite and ferrosillite are
the end member of pyroxene group.The mineral
wollastonite, although used as an end member to
describe pyroxene composition, is not a pyroxene.

 THE ORTHOPYROXENE
Enstatite = Mg SiO3
Ferrosilite = Fe SiO3
Hyperthene =(Mg Fe)2 Si2O6
 Here complete solid solution exist between enstatite and
ferrosilite. They are substitute for each other with
6 to 8 coordination site .

 THE CLINOPYROXENE
Diopside = Ca Mg Si2O6
Hedenbergite = Ca Fe Si2O6
 Here solid solution exist between two end
member clinopyroxene i.e diopside and
hedenbergite.

 SODIUM PYROXENE
 The sodium rich pyroxene is also crystallized
in monoclinic crystal system ,so therefore it is
belong to clinopyroxene group.
The sodium pyroxene and iron bearing
pyroxene are found in alkaline igneous rocks of
various type.
 The sodium and aluminium bearing pyroxene
occur primarily in igneous or metamorphic
rocks formed under conditions of high pressure
and temperature (eg-jadeite,ompacite)

SILICATE STRUCTURE
 Pyroxene minerals are comes under single chain
(ionsilicates) silicate structure.
 Ionsilicate structure divided into two type.
I - Single chain structure .
II – Double chain structure .

I. SINGLE CHAIN STRUCTURE
 If two of the oxygens are shared in a way to make long
single chains of linked SiO4 tetrahedra, we get the
single chain silicates or inosilicates.
 The ratio of silicon to oxygen in single chain silicate
is 1:3 .
(Fig - Single chain structure)

II. DOUBLE CHAIN STRUCTURE
(Fig-Double chain structure)
 Two single chains lie side by side by side so that all the right
sided tetrahedrons of the left chain are linked by an oxygen
to the left sided tetrahedrons of the right chains.
 The ratio of silicate to oxygen in double chain
silicate is 4:11 .

 MODE OF OCCURRENCE
 Pyroxene is the name of the group of dark colored rock-
forming minerals found in igneous and metamorphic rocks
throughout the world.
 They are most abundant in the dark colored igneous rock,
such as basalt and gabbro, that comprise most of the
oceanic crust. Pyroxenes are also important minerals in
many peridotites rock(harzburgite,wehrlite) . Rocks of the
upper mantle are composed mainly of olivine and
pyroxenes.
 Prroxene is also present in various type of metamorphic
rock . The most important are –
Granulite- Is a high grade metamorphic rock mostly
composed orthopyroxene and clinopyroxene.
Eclogite- It is a high temperature and high pressure
metamorphic rock consists omphacite (high pressure cpx and
Na rich)and garnet.
 Pyroxenes are not abundant in sedimentary rocks because
pyroxenes rarely form at low temperatures and are very
susceptible to chemical and physical weathering.

 PHYSICAL PROPERTIES OF PYROXENE
 Chemical classification – Silicate
 Color – Dark green to dark brown or black
 Streak – White
 Lusture – Vitreous to dull
 Diaphaneity – Semi-translucent to opaque
 Hardness – 5 to 7
 Specific gravity – 3 to 4
 Cleavage – Two set of cleavage
 Crystal system – Orthorhombic or monoclinic

 OPTICAL PROPERTIES
 2v – Biaxial 60˚-90˚
 Colour- Mg rich opx are are colourless and, Fe rich show pale green to pale brown.
 Pleochroism- Colour opx show faint pleochroism.
 Cleavage- ~90˚ 2 sets (exact 87˚-93˚)
 Relief- Moderate(En) to high(Fs)
 Birefringence-1st order colour (opx), 2nd order colour (cpx)
 Extinction- Parallel extinction of minerals such as orthopyroxene.
 Habit- Early formed opx in igneous rock appear as short prismatic crystal.

 USES OF PYROXENE
( Fig – Crush trap rock ) ( Fig – Chromo diopside )
 Pyroxene mineral are minor to secondary components of some rock that are
use as crushed stone . A few pyroxene are used as gem material . It is also
used as construction industry and decorative tile and facing stone.

 REFERENCES..
 Mineralogy- Dexter Perkins
 Rutleys Elements Of Mineralogy- C.D Gribble
 Earth Materials –Kevin Hefferan
 https://geology.com/minerals/pyroxene.shtml
 https://www.alexstrekeisen.it/english/pluto/pyroxene.php

PYROXENE MINERAL GROUP.pptx

More Related Content

What's hot (20)

Similar to PYROXENE MINERAL GROUP.pptx (20)

More from Imposter7 (19)

Recently uploaded (20)

PYROXENE MINERAL GROUP.pptx