As we know, three important factors like temperature, pressure and chemically active fluid dominant roles in bringing about transformation of the original and mineral deposits. These metamorphic changes are sometimes responsible in giving rise to important mineral deposits, which conveniently grouped into two classes:

(i) Metamorphosed deposits:

These are formed as a result metamorphism of pre-existing mineral-deposits, due to which ore acquire new-textural characteristics like granular, schist banded etc.

Through the process of metamorphism the original mine usually get anhydrated, and transformed into new-minerals. Thus limonite and other iron-hydroxides are transformed into haematite and magnetite; psilomelene and manganite are replaced by braunite and hausmannite etc. Certain ferruginous and manganiferous sediments undergo metamorphism and give rise to iron and manganese ore deposits.

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It may also so happen that during the process of metamorphism, the originally dispersed ore mineral get segregated giving rise to workable-economic deposits.

(ii) Metamorphic mineral deposits:

These deposits are formed due to recrystallisation and/or recombination of certain miner constituents of the rocks during regional or contact metamorphism. Regional progressive metamorphism has the greatest significance in the formation of metamorphic deposits. The shape, constitution and composition of mineral bodies are altered in consequence of it.

The most common examples of the non-metallic mineral, which are formed through this process are graphite, garnet, kyanite sillimanite, asbestos, steatite, etc.

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Metallic minerals like corundum, rutile, ilmenite, magnetite, uranium, pyrite, native copper (Jake superior type) etc.

The type of mineral deposits resulted are dependent on the facies of metamorphism.