The document discusses the olivine group of minerals. It describes the history of the term "olivine" and defines key members of the olivine group. Olivine is a common mineral found in mafic and ultramafic igneous rocks. It is the first mineral to crystallize from cooling magma due to its high melting temperature. Olivine weathers quickly on Earth's surface, breaking down to form fertile volcanic soils. It has various industrial and gemstone uses.

2.  1. Introduction.
 2. Olivine Group
 3. Geological occurrence of Olivine
 4. Physical Properties
 5. Optical Properties
 6. Members Under Olivine Group
 7. Uses
 8. Weathering
 9. Conclusion
 10. Bibliography

3. Name – Kaijirsong Rongpi
Roll No - 377
B.sc 2nd Semester
Geology Department
Aryavidyapeeth
College,Guwahati

4.  The Evolution of the term ‘OLIVINE’ is complex. The earliest name given
to an Olivine group species was Chrysolite and was named by Johan
Gottschalk Wallerius in 1747, although the name Chrysolite was later used
by Balthasar George Sage in 1777 for what is now known as Prehnite.
Chrysolite was renamed Olivine in 1789 by Abraham Gottlieb Werner for
the usual Olive green color of this mineral.
 The second member of the group was named tephroite in 1823 by Johann
Friedrich August Breithaupt. The commom Mg-dominant member of the
group was renamed Forsterite by Serve-Dieu Abailard Levy in 1824. Hemy
C. Salmon in 1859 explicitly used “olivine group” to designate minerals
which were chemically analogous to Olivine. In the USA, James Dwight
Dana and George Jarvis Brush began organizing groups in their system
and organized the “Chrysolite group” in 1868 and that group name was
continued into 1892 by Edward Salisbury Dana.
 The Universal Acceptance of “ Olivine Group ” occurred in the Twentieth
Century.

5. Olivine is a magnesium iron silicate with the formula (Mg2+,Fe2+)2SiO4 Thus it is a
type of nesosilicate. It is a common mineral in Earth’s subsurface but weathers
quickly on the surface.
The two minerals Fayalite and Forsterite are referred to as the Olivine Series
These are also the end-members of this olivine group and the melting
temperature of Fayalite is about 1900 centigrade where this Fayalite ; melting
temperature is higher than Forsterite.
This is a group of rock-forming silicates that are typically found in mafic and
ultramafic igneous rocks such as basalt, gabbro, dunite, diabase and peritodite.
The minerals are olive green or brown in color. All these minerals crystallize in
orthorhombic system

6.  Most olivine are found at earth’s surface is in dark-colored igneous rocks. It
usually crystallizes in the presence of plagioclase and pyroxene to form
gabbro or basalt. These types of rocks are most common at divergent plate
boundaries and at hot spots within the centers of tectonic plates.
 Olivine has a very high crystallization temperature compared to other
minerals. That makes it one of the first minerals to crystallize from a
magma. During the slow cooling of a magma, crystals of olivine may form
and then settle to the bottom of the magma chamber because of their
relatively high density. This concentrated accumulation of olivine can
result in the formation of olivine-rich rocks such as dunite in the lower
parts of a magma chamber.
 Crystals of olivine are sometimes formed during the metamorphism of a
dolomite. The dolomite contributes magnesium and silica which is
obtained from quartz and other impurities in the limestone. When olivine
is metamorphosed it is transformed to serpentine

7. During
metamorphism,
olivine is altered to
serpentine
(amphibole).

8. 1. Color – Olive Green, but can be yellow-green to bright green
2. Crystal Habit – Massive to Granular
3. Cleavage – Poor Cleavage
4. Fracture – Conchoidal
5. Hardness – 6.5 to 7
6. Luster – Vitreous
7. Streak – Colorless
8. Diaphaneity – Transparent to Translucent
9. Specific Gravity – 3.2 to 4.4
10. Crystal System – Orthorhombic

9. 1. Color – Colorless and non pleochroic
2. Refractive index – High positive relief, high refractive index
3. Birefringence – Strong (0.037)
4. Extinction - Straight

10. 1. Calcio-Olivine Ca2SiO4
2. Fayalite Fe2+
2SiO4
3. Forsterite Mg2SiO4
4. Glaucochroite CaMn2+SiO4
5. Kirschsteinite CaFe2+SiO4
6. Laihunite Fe2+Fe3+
2(SiO4)2
7. Liebenbergite (Ni, Mg)2SiO4
8. Monticellite CaMgSiO4
9. Olivine (Mg2+,Fe2+)2SiO4
10. Roepperite (Fe2+
2,Mn,Zn)SiO4
11. Tephroite Mn2+
2SiO4

14.  Common impurities present in here are Ti,Al,Mn,Mg,Na,K and P
 Chemical Formula is CaFe2+SiO4
 It is also known lime-iron olivine.

15.  In this minerals, there is
an impurities of Fe and
Co.

19. Olivine minerals
are common in
igneous rocks.
Peridotite
Basalt
Gabbro

20. Olivine is common in
meteorites.
Olivine was brought back to
Earth from Comet Wild by
NASA’s Stardust mission.

21. Olivine is the gemstone Peridot. It
has been a human favorite for
centuries, and is often used as a
birthstone for August.

22. Olivine minerals are used in
industry as abrasives. Olivine is used in steel
manufacturing.
USES

23. Olivine is not only used in industry but most Olivine is used in metallurgical
processes as a slag-conditioner. High Magnesium Olivine (Forsterite) is added to
lash furnaces to remove impurities from steel and to form a slag.
Olivine has also been used as a refractory material. It is used to make refractory
brick and used as a casting sand. Both of these uses are in decline as alternative
materials are less expensive and easier to obtain.
Olivine is the green in green sand beaches.

24. WEATHERING
Olivine is one of the weaker common minerals on the surface according to the
goldich dissolution series. It alters into Iddingsite readily in the presence of water.
Artificially increasing the weathering rate of olivine . The presence of Iddingsite
on Mars would suggest that liquid water once existed there, and might enable
scientists to determine when there was last liquid water on the planet.

25. Olivine minerals tend to break
down (weather) very easily at the
Earth’s surface.
The iron and magnesium released
by this weathering process helps to
make volcanic soils very fertile.

26.  From the above mentioned theme’ Olivine”, we came to know that Olivine
Group consist of lots of minerals in it i.e. Fayalite , Forsterite etc
 Olivine are common in jewelry or as a gemstones
 Weathering process also plays an important role where olivine could break the
earth’s surface very easily.

27.  http://www.wikipedia.com/olivinegroup
 A textbook of Mineralogy by G.B Mahapatra
 http://www.slideshare.net.com/olivine
 A textbook of Geology by P.K Mukerjee
 http://www.geology.com/olivinegroup
 http://www.mindat.org/olivinegroup
 A manual of mineralogy by Dexter and Perkins