In the example described above, skarn formed in a carbonate rock unit adjacent to a magma intrusion. There are numerous other geological situations where skarn can be formed. These include:

• skarn associated with seafloor hydrothermal systems;
• skarn formation along faults and shear zones;
• skarn forming at depth in areas of regional metamorphism;
• skarn above subduction zones;
• and many other geological situations.

Skarn can form with various water inputs. These include include:

• water from magma;
• shallow groundwater;
• seawater; or
• deep brines.