15 Questions
What is the branch of applied geology dealing with the genetic study of ore deposits?
Ore Geology
Define ore and ore deposits.
Ore: metalliferous mineral or an aggregate of metalliferous minerals, more or less mixed with gangue, that can be won at a profit. Ore Deposits: contain an unusually high concentration of particular element(s) or parts of the crust where ores are concentrated.
What are ore minerals and gangue minerals?
Ore minerals have economic value and are those from which metals are extracted, e.g. chalcopyrite and galena. Gangue minerals are usually worthless, non-metallic minerals of a deposit.
What does the term 'syngenetic' refer to in the context of ore deposits?
Ore deposits that form at the same time as their host rocks.
What is metallogeny and metallotect?
Metallogeny is the study of the genesis of mineral deposits, and metallotect refers to any geological, tectonic, lithological, or geochemical feature that has played a role in the concentration of elements in the Earth's crust.
What is the specific gravity of gold?
19gm/cc
Name one economically important placer deposit mineral other than gold.
Diamonds (carbon)
What chemical process can concentrate minerals through chemical weathering and erosion?
Progressive dissolution of silica from clays in wet soils
What is the specific gravity of Cr spinel compared to basaltic magma?
Cr spinel: 4800 kg/m3, Basaltic magma: 2500 kg/m3
What type of melt can be rich in niobium, tantalum, rare earths, copper, thorium, and phosphorous?
Carbonate melts
What are the primary mechanisms for concentrating minerals into ores?
Sorting by density or sorting by solubility
What are the three main steps for making a placer deposit?
A. Weathering removes mineral particles from country rock. B. Kinetic energy of high-velocity stream transports mineral particles. C. Where kinetic energy drops suddenly, high-density particles stop, lower density particles continue
What is the geochemical anomaly that characterizes an ore?
An ore is a geochemical anomaly resulting from the removal, transport, and concentration of specific elements, compounds, or minerals from ordinary rock.
Give an example of how mechanical weathering and erosion can concentrate minerals.
Quartz sand typically mined from ancient beaches, sand bars, etc.
What are placer deposits, and how are they formed?
Placer deposits are deposits of heavy mineral particles in a stream bed, formed through the steps of weathering, transportation, and density contrasts.
Test your knowledge of major theories of ore genesis, ore forming processes, texture and structure of ore and gangue minerals, fluid inclusions, wall rock alteration, geothermometry, geobarometry, plate tectonics, and magmatic-hydrothermal ore-forming processes.
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