Ha or Hectare – Area which has sides totalling 400 metres in length. A square hectare is area of one hectare that has four equal sides of 100 metres each.
Hadean – Earliest eon in the history of the Earth that spanned from the first accretion of planetary material until the date of the oldest known rocks. The period from 4567 to 4000 million years ago.
Halco – Drilling a percussion drill hole
Half-Life – In radioactivity, it’s the time required for half of a homogeneous sample of radioactive material to decay. In chemistry it is the time required for half of a given quantity of material to undergo a chemical reaction.
Halfspace – Volume in which half is “air” and the other half is a constant value. Geophysicists consider the earth to be a “halfspace” wherein the whole volume that is visible has only a constant value of the relevant physical property.
Hanging Valley – Tributary valley in a glacial landscape whose mouth is in the steep wall of the main valley high above its floor.
Hanging Valley – Former glacial tributary valley that enters a larger glacial valley above its base, generally high up on the valley wall.
Hard Water – Water that contains sufficient dissolved calcium and magnesium to cause a carbonate scale to form when the water is boiled or to prevent it from sudsing when combined with soap.
Heap Leaching – Process whereby valuable metals such as gold and silver are leached from a heap, or pad, of crushed ore by leaching solutions percolating down through the heap and are collected from a sloping, impermeable liner below the pad.
Heat Conduction – Transfer of the rapid vibrational energy of atoms and molecules which constitutes heat energy through the mechanism of atomic or molecular impact.
Heat Engine – Device that transfers heat from a place of high temperature to a place of lower temperature and does mechanical work in the process.
Hectares – Area which has sides totalling 400 metres. A square hectare is an area of one hectare that has four equal sides of 100 metres each.
Hematite – Greyish, blackish metallic iron oxide mineral with symbol Fe2O3. It powders to a red colour. It’s the principal ore of iron. Another variety known as specular hematite is a shiny, hard variety of the mineral and is referred in the jewelry industry as Alaska Black Diamond.
High Grade – Rich ore of any metal or mineral. With uranium, ore containing more than 2% uranium is considered high grade. As a verb, it refers to selective mining of the best ore in a deposit.
Highly Enriched Uranium – HUE is any form of uranium with a U-235 concentration of 20% or higher.
Hill – Natural land elevation of generally less than 1000 feet above its surroundings, with a rounded outline.
Hogback – Ridge formed by slower erosion of hard strata that has two steep equally inclined slopes.
Hooke’s Law – Principle that the stress within a solid is proportional to the strain wherein strains are of a few percent or less.
Horizon-In-Sediments – Relates to a specific stratagraphic interval.
Hornblende – Black or dark-green mineral that forms needle-shaped or fibrous crystals. The most common member of the amphibole group and usually occurs in both igneous and metamorphic rocks.
Hornfels – Metamorphic rock formed by the contact between mudstone/shale or other clay-rich rock and that of a hot igneous body, and represents a heat-altered equivalent of the original rock. This process is referred to as contact metamorphism.
Horst – Elongated, elevated block of crust forming a ridge or plateau and typically bounded by parallel, outward-dipping faults.
Host Rock – Body of rock in which mineralization of economic interest occurs.
Hosted – Contained within a hyperspectral survey an airborne survey method that measures reflected light in the visible spectrum hypogene below surficial weathering.
Hot Spring – A spring whose waters are above both human body and soil temperature as a result of plutonism at depth.
Humus – Decayed part of the organic matter in soil.
Hydration – Chemical reaction, generally in weathering, which adds water or hydroxyl groups to a mineral structure.
Hydraulic Conductivity – Measure of the permeability of a rock or soil as the volume of flow through a unit surface, in unit time, with unit hydraulic pressure difference being the driving force.
Hydrocarbon – Organic chemical compound made up of carbon and hydrogen atoms arranged in chains or rings.
Hydrologic Cycle – Cyclical movement of water from the ocean to the atmosphere, through rain to the surface, through runoff and groundwater to streams, and back to the sea.
Hydrology – Science of that part of the hydrologic cycle between rain and return to the sea. The study of water on and within the land.
Hydrothermal Activity – Process involving high-temperature ground-waters, especially the alteration and emplacement of minerals and the formation of hot springs and geysers.
Hydrothermal Vein – Cluster of minerals precipitated by hydrothermal activity in a rock cavity.
Hydrothermal Vent – Place on the seafloor, generally associated with spreading centers, where warm to super-hot, mineral-rich water is released and which may support a diverse community of organisms.
Hypocenter – Point below the epicenter at which an earthquake actually begins known as the focus.
Hypsometric Diagram – Graph that shows in some way the relative amounts of the earth’s surface at different elevations with respect to sea level.