Vadose Zone A hydrogeological term that represents the volume of rock and unconsolidated materials between the ground surface and the underlying water table, in which pores and cracks are...

Vapor-Dominated Reservoir The highest grade of geothermal resource in which self-flowing wells produce dry steam from a reservoir containing a mixture of hot water and steam. Larderello,...

Wairakite A zeolite mineral of hydrothermal origin that was first identified in the Wairakei geothermal field in New Zealand by Alfred Steiner. It forms clear to white prismatic crystals,...