Bauxite is the primary ore for aluminum production, a vital non-ferrous metal used in various industries, with significant reserves found globally, especially in countries like Australia and Guinea. It is characterized by its chemical composition, with varying levels of alumina, silica, iron, and titanium. India holds substantial bauxite resources, primarily in Odisha and Andhra Pradesh, with the majority being of metallurgical grade.

1. Bauxite:
1. Bauxite is the principal ore for the production of aluminium, which is one of the most important non-ferrous metals with
wide applications in various sectors. Aluminium become an integral part of our everyday life. Its requirement is
increasing for domestic appliances, transmission of power, transport, defense equipment and packaging.
2. Bauxite is basically an aluminous rock that contains hydrated aluminium oxide as main constituent and iron oxide, silica
& titaniam as minor constituents present in varying proportions.
3. Bauxite ore are Diaspore and Boehmite, Al2O3.H2O; Gibbsite or Hydrargillite, Al2O3.3H2O, Hematite or goethite are
present in as iron oxide in bauxite; silica as clay; and free quartz & titanium as leucoxene or rutile.
4. Bauxite is typically a soft material with a hardness of only 1 to 3 on the Mohs scale. It is white to gray to reddish brown
with a pisolitic structure, earthy luster and a low specific gravity of between 2.0 and 2.5.
5. Bauxite use as principle ore of aluminium, as well as It is also an essential ore for Refractory and Chemical industries.
6. In world Bauxite deposition occur in two type first, the most common one is Lateritic origin, deposited by weathering of
Aluminium rich rock in tropical or subtropical environment. Second, one is Karstic origin, these type of bauxite occur
above the carbonate rock (limestone and dolomite), formed when dispersed clay layer in the limestone, during chemical
weathering the clay transformed into bauxite.
7. India has 3,896 million tons of resources of bauxite which is sufficient to meet both domestic and export demands.
(Source IBM year book 2020).
8. Bauxite is found in abundance at many locations around the world. Top leading bauxite producing countries were:
Australia, Guinea China, Brazil, India, Indonesia, Jamaica, Russia (Source: BGS World Mineral Production, 2015-2019).
Chemical Character of Bauxite:
1. Alumina: The alumina content in the bauxite deposit in the world vary from 20 to 70%, The highest Al2O3 (67-73%)
has been encountered in gibbsite-rich concretions, whereas lowest alumina value is found in concretions and intercalation
of ferritic or kaolinitic bauxites.
2. Silica: Silica (Si02) in bauxite is mainly found as kaolinite and quartz which are respectively termed reactive and 'free'
silica together called 'total silica. Reactive silica up to 10% are generally referred to as bauxite. Those having more than
10% are called' siliceous bauxite and those containing more than 23% Si02 are called bauxitic kaoline (bauxitic clay).
Bauxites with free-silica {quartz) up to 5% are known as quartz bearing' bauxite.
3. Iron: The iron content in bauxite samples ranges from 0.5 to 65 % the common range being 1 to 40%. The low iron
content in the parent rocks is reflected in low iron content in bauxite deposits. The majority of the laterite bauxite deposits
contain 1~ 3% Fe2O3, such, as most of Guinean, Indian and Australian bauxites. A smaller number of deposits derived
from basic rocks, contain 25 - 35% iron.
4. Titanium: In bauxite, the titanium (TiO2) ranges from 0.1 to 25%, the most common range being 1-4%. The highest
TiO2 content have been reported from the basalt-derived bauxite deposits of M. P. India (8-10%).
5. LOI (Loss of Ignition): Lateritic bauxites are characterized by high value of combined water mainly because of high
gibbsite content of most surface deposits. The loss on ignition in bauxites can be close to that of gibbsite, that is, it can

2. frequently reach 31-34%. The average loss on ignition of the bauxite horizon is highest~ (28-31%) in the high alumina,
trihydrate type. The lowest average loss on ignition (15-19%) is found in the monohydrate type-boehmitie and diasporic
deposits.
Characteristics of Indian Bauxite deposits:
1. Eastern Ghats (A.P. & Orissa): The bauxite of this belt is low in silica (1.5 - 3.5%), low titaniam (1-3%) high iron (8-
28 % Fe2O3) and contains less than 1% P2O5, V2O5, MnO, MgO, CaO, Na2O3 and K2O put together. The main
aluminous mineral in this deposit is gibbsite (more than 95%) while the boehmite is insignificant. Anatase is the major
titanium mineral followed by rutile and ilmenite. Goethite and hematite occur in variable proportions.
2. Western Ghats (Karnataka and Maharashtra): In this belt bauxite shows average Al2O3 content is 51%, whereas
Si02, Fe2O3, Ti02 and LOI constitute 3.5 %, 13%, 4.8% and 27% respectively. The major aluminous mineral is gibbsite
followed by boehmite and traces of diaspore. About 20-25% alumina occurs in form of boehmite More than 90% silica
is locked up in kaolinite.
3. Inland high level Plateau (Jharkhand, Madhya Pradesh & Chhattisgarh): A large number of scattered bauxite
deposits of Jharkhand, Madhya Pradesh & Chhattisgarh are classified under this group. In physical chemical characters
and mineralogy, the is similar to Western Ghats deposits. The only exception is higher content of titanium and noticeable
quantity of diaspore in some deposits falling under this group.
4. Coastal Plains: The bauxite deposits of Kutch and Saurashtra in Gujarat uniquely occur nearer to MSL. These bauxites
are known for their superior quality, and are most suitable for refractory and chemical industries. Two types of bauxite
formations for example hard massive boulder type, characterized by very high alumina (>55% Al2O3) low to medium
silica (1.5 - 5%) and low iron (<10% Fe2O3 The dominant aluminous mineral is gibbsite followed 'by boehmite and
traces of diaspore. The silica is mostly found in kaolinite and quartz is present only in small quantity.
Ideal Definition of Bauxite based on IBM:
All sample with more than 30% of Al2O3 and less than 7% SiO2 are classify as Bauxite. While sample have 25 to 30%
of Al2O3 and more than 7% of SiO2 are called as Aluminous laterite.
Laterite is also defining in two way (I) Aluminous Laterite: Fe2O3/Al2O3 < 1 and SiO2/Al2O3 < 1.33, (II)
Ferruginous Laterite: Fe2O3/Al2O3 > 1 and SiO2/Fe2O3 < 1.33
Reserves/Resources of Bauxite in India:
Bauxite reserves /resources in India, based on UNFC system placed at 3,896 million tones. These resources include 656
million tones Reserves and 3,240 million tones remaining Resources.
Odisha alone cover 51% of country's resources of bauxite followed by Andhra Pradesh (16%), Gujarat (9%), Jharkhand
(6%), Maharashtra (5%) and Madhya Pradesh & Chhattisgarh (4% each).
In India 77% resources of bauxite are of Metallurgical grade and 4% resources are coming under refractory and chemical
grades. (Source IBM Year Book 2020).
Top countries which have highest reserves in bauxite were Australia, Brazil, China, Guinea, India, Indonesia, Jamaica,
Kazakhstan, Malaysia, Russia (Source: USGS, Mineral Commodity Summaries, 2020).