Economic Geology

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Economic Geology
2013-09-04 08:05:59

Economic Geology Terms
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  1. Alteration
    Any change in the mineral composition of a rock caused by physical or chemical means, especially by hydrothermal fluids. Alteration is milder and more localized than metaporphism.
  2. Assay
    An analysis of the proportions of metal in an ore. Composition, purity, weight, or other properties of economic interest are tested.
  3. Average Grade
    The average quantity or percentage of ore mineral content in an ore body.
  4. Base Metal
    A common and chemically active metal (it oxidizes or corrodes easily) - lead ot copper for example.
  5. Coalification
    The process that produces coal of increased rank.
  6. Density
    The mass or weight of a substance per volume that it occupies.
  7. Dispersion
    The process by which elements move away from the enriched ore zone.
  8. Dolomitization
    The process by which limestone is converted to dolomite by the replacement of calcium carbonate by magnesium carbonate.
  9. Eh
    Oxidation potential; the potential of a half-cell, measured against the standard hydrogen half-cell.
  10. Epigenetic
    An ore deposit that originates later than the enclosing host rocks.
  11. Epithermal
    Shallow hydrothermal.
  12. Exhalite
    The chemical product of exhalation; a deposit formed by the interaction of volcanically derived water and sea water with subjacent rocks.
  13. Gangue
    Valueless rock or mineral aggregates in an ore; economically undesirable.
  14. Giant Field
    A petroluem field containing 500 million barrels or more of recoverable oil; a natural gas field which has a minimum of 3.5 trillion cubic feet of recoverable gas.
  15. Gossan
    An iron-bearing weathered product overlying a sulfide deposit.
  16. Grade
    A coal classification based on degree of purity.
  17. Hydrothermal
    Pertaining to hot water, the action of hot water, or the products of hot water. The term is generally used for all hot water whether or not the water is of magmatic origin.
  18. Metasomatism
    The process of practically simultaneous solution and deposition of a new mineral in an old mineral by means of interstitial fluids. The replacement occurs at constant volume with little disturbance of structural or textural features.
  19. Pathfinder
    A relatively mobile element whose geochemical properties are used to more easily find a deposit of greater importance or value.
  20. pH
    The negative log10 of the hydrogen-ion activity in solution; a measure of the acidity or basicity of a solution.
  21. Porphyry
    An igneous rock that contains phenocrysts in a fine-grained matrix.
  22. Precious metal
    Gold, Silver or minerals of the platinum group.
  23. Pyritization
    Introduction of, or replacement by, pyrite, a common process of hydrothermal alteration.
  24. Rank
    The degree of progressive diagenesis or metamorphism of peat (coalification)
  25. Replacement
    A solid-state change in composition of a mineral accomplished by diffusion of a new material in and an old material out.
  26. Reserves
    Deposits that are economically available and may be extracted profitably with existing technology; a subset of resources.
  27. Resources
    Naturally occuring deposits in such amounts or concentrations to be minable now or in the future, including reserves.
  28. Silicification
    The introduction of, or replacement by, silica.
  29. Skarn
    Silicate rocks of complex metamorphic-metasomic mineralogy formed in carbonate rocks in a contact metamorphic aureole.
  30. Specific Gravity
    The ratio between the density of a substance and the density of water.
  31. Stoping
    Extraction of ore in an underground mine by working laterally in a series of levels in the plane of the vein.
  32. Stratabound
    A mineral deposit confined to a single stratigraphic unit.
  33. Stratiform
    A special type of stratabound deposit in which the ore constitutes a layer or layers in the rock.
  34. Supergene Enrichment
    A near-surface process of mineral deposition in which metals are leached by acidic solutions, carried downward, and re-precipitated, enriching the sulfide minerals already present.
  35. Syngenetic
    A mineral deposit formed contemporaneously with, and by the same processes as, the enclosing rocks.