In ore deposit geology, hypogene processes occur deep below the Earth's surface, and tend to form deposits of primary minerals, as opposed to supergene processes that occur at or near the surface, and tend to form secondary minerals.
[1] At great depth the pressure is high, and water can remain liquid at temperatures well above 100 °C.
Hot aqueous solutions originating from magmas, deep sedimentary basins, or areas of elevated geothermal gradients can contain metals and other ions derived from the magma itself or from leaching of sedimentary, igneous, or metamorphic rocks.
Hypogene deposition processes include crystallization from the hot aqueous solutions flowing through the Earth's crust, driven by temperature and pressure gradients, as well as topographic, orogenic, and structural changes and/or controls.
[2] Major dissolved components are chlorine, sodium, calcium, magnesium and potassium, and other important components include iron, manganese, copper, zinc, lead, sulfur (as SO2−4 or S2− or both) carbon (as HCO−3 and CO2) and nitrogen (as NH+4).