sentences:  The mineral may have formed through the melting of acidic snow, or the melting and discharge of sulfur-rich water from the base of the polar ice cap.However, the presence of gypsum does not necessarily require large surface water bodies (e.g., playa lakes).The mineral could have formed in volcanically heated groundwater in the shallow subsurface and later been exposed and concentrated by wind erosion and winnowing ("eolian mining").