Exploration & Mining Glossary

Hanging wall - Refers to the mass of rock strata overlying the orebody (see Ore). For the opposing side, see Footwall.

High grade - Rich ore. As a verb, it refers to selective mining of the best ore in a deposit.

Host rock - The rock surrounding an ore deposit.

Hydrothermal alteration - Occurs from the movement of hydrothermal (heated waters in the Earth's crust) fluids circulating through rocks, these hot fluids can mineralogically, chemically and texturally alter these rocks forming new mineral assemblages. Example; pyroxenes, amphiboles and biotite can alter to chlorite under hydrothermal conditions.

Hydrothermal breccia - Are a subclass of the breccia family (rock consisting of angular fragments of rocks within a finer grained matrix), formed by the hydrofracturing of rocks by highly pressured hydrothermal fluids. This allows for accommadation space within the matrix for sulphide hosting veins to occupy.