Outbursts occur when mining evaporite deposits. These outbursts are associated with gasses that are held within fluid inclusions. Because of the high stresses that can exist in the evaporites along with the extremely low permeabilities the fluid pressure may be at the stress within the evaporite mass. At these pressures some of the gasses, especially carbon dioxide, may be liquid. On shearing with mining the mass may dilate permitting the gas to expand and drive the failure. Cases of large emissions of carbon dioxide have occurred on such outbursts. These have formed carbon dioxide ice due to the cooling that occurs on expansion.