Chromite

Chromite

Source : Wikipedia

Chromite (FeCr2O4) is the only ore of chromium. Chromite deposits occurs closely related to the anorthosites, harzburgite, dunite, pyroxinite and other ultrabasic rocks. Chromite deposits are divided into 2 categories

1. Stratiform 

2. Podiform

Stratiform Chromite Deposits

• In early magmatic crystallization, these deposits form and segregates to the bootom due to gravity settling effect.

• They are large masses of layers alternate with ultramafic rocks. These are of great economic significance.

• They are mostly occurs as intracratonic deposits.

• Age is much older than podiform deposits, as they are of precambrian. Ex : Orissa chromite complex, Sittampundi Anorthosite complex.

Podiform Chromite Deposits

• When chromite starts accumulating, it can form stratas or can form 'pods' in host rock, thus pods form deposits are called Podiform chromite deposits. 

• These deposits occurs as irregular pods and lenses in the ultramafic section of ophiolites. These pods and lenses vary from pea size to to hundred of meters in size.

• They mostly occurs in suprasubduction szones. They form in MOR setting and found in subduction settings in ophiolites and melange. Their age is Mesozoic to recent.

• These are of not much economic importance.

INDIAN DEPOSITS

click on image