Here is your essay on Manganese
The chief sources of manganese are the oxide-minerals. There are a total of 156 manganese minerals of which 44 are found in India. According to the composition of manganiferous ores in regard to the proportion of manganese to iron, it is customary to use the term ‘manganese ore’ to those containing over 40% of manganese. The most common economic minerals are:
Other important manganese minerals which are of specially Indian origin are as follows:
Sitaparite, Hollandite, Jacobsite, spessartite etc.
Manganese ore deposits may be formed as follows:
1. Hydrotherraal deposits:
It is formed by magmatic hot-water solution
2. Sedimentary deposits:
Due to chemical precipitation.
3. Residual deposits:
Due to residual concentration.
Through the action of underground water containing manganese.
5. Metamorphosed deposits:
Due to metamorphism of above said deposits
On the basis of their mode of occurrence and association with, different kinds of country-rocks, however, the Indian manganese deposits have been classified as:
(a) Gonditic ores:
Which are associated with metamorphosed manganiferous sediments.
(b) Kodnritic ore:
These are produced due to reaction between the country-rocks and an invading magma of granitic composition. The hybrid rocks, thus produced are called kodurites
(c) Lateritoid ores. These are produced due to metasomatic replacement and residual concentration.
Mode of occurrence:
Manganese deposits occur as bedded sedimentary deposits, metamorphosed deposits, residual deposits or hydrothermal deposits.
Distribution in India:
In India, extensive and rich manganese deposits occur in Madhya Pradesh, Orissa, Bihar, Andhra Pradesh, Maharashtra and Karnataka.
According to the genetic classification of ‘Indian Manganese Deposits’ by Supriya Roy the followings are the types of deposits and their area of distribution:
1. Syngenetic deposit:
(a) Regionally metamorphosed manganese sediments, associated with pelitic and psammitic rocks and very often with manganese- silicate rocks (Gondites). Example: Mansar formation of Sausar group of M.P. and Maharashtra.
(b)Regionally metamorphosed manganese sediments associated with marbles and calc-silicates, e.g., Mn-ore bodies in Lohangi marbles of Sausar group of MP and in calc-silicate rocks of khondalite group in Andhra Pradesh and adjacent parts of Orissa (Kodurites).
(c) Contact-metamorphic deposits of Gujarat:
Due to thermal action of granitic intrusive on pre-existing manganese sediments, associated with impure limestone.
(a)Redsidually concentrated deposits of Goa, KeonjharBonai (Orissa) etc.
(b) Replacement and cavity-filling deposits:
By meteoritic water, through precipitation from ‘gels’ or solution.
Other important distributions are:
Barjamda and Singhbhum district.
Residual deposits occurring within the country rooks of Dharwarian age.
(i) It is one of the important ferro-alloy metals.
(ii) Wide application in steel industries.
(iii)In chemical industries for dry batteries.
(iv) As a decolouriser in glass industry and also as oxidising agents.
The manganese ores on the basis of their manganese contents may be classified into the following grades.
(a) Chemical grade 82-87 % of Mn.
(b) Metallurgical grade:
First grade more than 48% of Mn.
Second grade 45-48 % of Mn.
Third grade less than 45 % of Mn.
(c) Manganese ore grade 35 to 45% of Mn.
(d) Ferruginous Manganese ore grade 10 to 35% of Mn.
(e) Manganiferous iron ore grade less than 10% of Mn.
For trade purposes, Indian Mangnese ores are classified as:
(a) Battery grade 80-86% of Mn02.
(b) Peroxide grade’ 78% Mn02+4% Fe.
(c) High grade 46 to 48% of Mn.
(d) Low grade 38 to 40% of Mn.
(e) Ferruginous grade 30-35% of Mn.
In the paints and pigments as well as in Fertiliser industries also manganese is used.