Bauxite types, mineralogy, Indian occurrences

2. CONTENTS
1. INTRODUCTION
2. MINERALOGY & USES
3. IMPORTANT BAUXITE DEPOSITS OF INDIA
4. CONCLUSION

3. INTRODUCTION
• Bauxite is a naturally occurring heterogeneous material composed of hydrated
aluminium oxide namely gibbsite ,boehmite ,diaspore with impurities of iron
hydroxide and titanium oxide.
• Pierre Berthier named bauxite after the village les Baux de Provence in southern
France, where it was first discovered in 1821.
• India is endowed with large reserves of bauxite. It is the 5th
largest producer in
the world.

4. • Bauxite is produced by chemical weathering typically under tropical and sub-
tropical conditions.
• Bauxite deposits are confined to 30ₒ
N &
30ₒ
S of the equator.
• Gibbsite : Al203. 3H2O; Boehmite: Al2O3.H20 and Diaspore: Al2O3.H2O are
the constituent minerals of bauxite
• Bauxite is the raw material most widely used in the production of aluminum
on a commercial scale.

5. • The usual color of bauxite is pink but if of low iron content it may tend to
become whitish in color and with increase in iron it is reddish brown in color.
• Very commonly bauxite deposits are associated with the rock type known as
laterite which forms a kind of ferruginous crust over any type of rock whether
igneous, sedimentary, or metamorphic.

6. • Of all bauxites mined, approximately 85% is converted to alumina
(Al2O3) for the
production of aluminum metal, an additional 10% goes to non metal
uses as various forms of specialty alumina, and the remaining 5% is used
for non-metallurgical bauxite.

7. • Bauxite forms by weathering of aluminous rocks under conditions favorable for
retention of alumina and the leaching of other constituents in the parent rocks.
The favorable conditions for bauxitisation are:
• Availability of rocks with minerals susceptible to removal by leaching to yield a
residue rich in Al.
• Porous rock to enable easy access and free circulation of water.
• Normal to abundant rainfall alternating with dry seasons.

8. • Vegetation and bacteria for leaching.
• Tropical to subtropical climates.
• Low to moderate topographic relief to permit a slow downward infiltration of
meteoric water.
• Long periods of stability in earth's history and preservation of bauxite so
formed.

9. • Bauxite deposits are classified into 3 types based on their genesis:
• LATERITIC BAUXITE formed from weathering of igneous, metamorphic or sedimentary
rocks.
• KARST BAUXITE formed in limestone terrain, and
• SEDIMENTARY BAUXITE formed from detrital material of transported Al-rich material.
85% of the worlds bauxite is of the Lateritic type, 14% of the karst type and 1% of the
sedimentary type.
All Indian bauxites belong to the Tertiary period.

10. • In the following slides, an overview of various features of bauxite-bearing
laterite profiles are presented.

11. FLAT-TOPPED PLATEAUS CONTINING BAUXITES

12. A TYPICAL BAUXITE-BEARING LATERITE PROFILE
SHOWING THE DIFFERENT LITHOZONES.

13. OOLITIC/PISOLITIC TEXTURE IN BAUXITE

14. A close-up view of Oolite and pisolite
bauxite.

15. LATERITE PROFILE SHOWING VERMICULAR STRUCTURE

16. CAVITY FILLING OF IRON IN LOWER PART OF
THE BAUXITE PROFILE

17. BAUXITE DEPOSIT DISTRIBUTION IN INDIABAUXITE DEPOSIT DISTRIBUTION IN INDIA

18. • Most of the Indian deposits are associated with laterite capping
occurring as blankets on the plateau and hill ranges of the
peninsular regions. However, occurrences of bauxite at lower
levels are also common.
•The major bauxite deposits of India occur in the central regions:
•Plateau regions bordering Bihar and M.P.
•Maikala range in M.P.
•Western ghats
•Eastern Ghats.
Smaller and isolated areas where bauxite deposits occur are at
Kharagpur hills, Bihar ;
Vindhyan plateau, U.P; Seoni, Kaimur and Malwa plateau and
Bailadila range in M.P;
Gandhamardhan plateau, Orissa; Shevroy hills, Nilgiris. In the
extrapeninsular India, high-grade diasporic bauxite deposits occur
in Jammu area of Jammu and Kashmir.

20. ANDHRA PRADESH:
• Andhra Pradesh is 2nd richest in bauxite deposits in the country.
• Reserves of 750 million tonnes of metal-grade bauxite have been proved in
forest and tribal tracts of Visakhapatnam, East Godavari and Vizianagaram
districts, crowning the Eastern Ghat hill ranges.
• These hills are essentially made up of the khondalite and charnockite group of
rocks of the Eastern Ghat Supergroup.

21. MADHYA PRADESH & BIHAR:
• Bauxite occurs as tabular bodies lenses and as irregular segregations in laterite
which blanket the summit of hills. The bauxite deposits are confined to
elevations above 1000m above MSL in all the areas of M.P and Bihar.
• The bauxites are derived from the weathering of Deccan Basalts.

22. MAHARASHTRA:
• Important bauxite deposits are located in Kolhapur, Kolaba, Ratnagiri, Satara
districts.
• The occurrences are confined to the top
of different plateaus of Western Ghats.
• The deposits are associated with laterites which rest on Deccan Trap basalt.

23. • A generalized laterite profile of the area is as follows:
Topsoil
Aluminous laterite
Bauxite
Aluminous and ferruginous Laterite
Lithomargic clay
Altered trap
Deccan trap.
•
• Bauxite deposits have resulted from weathering of Deccan traps.

24. CONCLUSION
• Bauxite is the raw material most widely used in the production of
aluminum on a commercial scale.
• In addition to Al2O3, there are several elements like Ga, Ti, Co, Ni
recovered from bauxite which add to its value and find industrial
applications.
• Since bauxite formation occurs under specific climatic conditions,
isotope investigations of its minerals helps unravel palaeoclimatic
conditions.

25. REFERENCE
• www.cyberorissa.com
• www.ipicolorisa.com
• www.jharkhand.gov.in
• www.aponline.gov.in
• Principles of Petrology-G.W TYRRELL
• Mineralogy-L.G BERRY, BRIAN MASON, R.V DIETRICH

26. THANK YOU