Economic Geology and Energy Flashcards

Which ore deposit type forms when magmatic fluids cool and precipitate minerals into surrounding fractures, often at temperatures between 200–400°C?

Answer: Hydrothermal vein deposit

Hydrothermal vein deposits form as mineral-rich fluids cool and precipitate ore minerals into fractures and faults.

The 'cut-off grade' in mining economics refers to:

Answer: The minimum ore grade that covers all costs of mining and processing

Cut-off grade is the minimum grade at which ore can be mined and processed while still covering all associated costs.

Unconventional natural gas trapped in fine-grained sedimentary rock and requiring hydraulic fracturing to produce is called:

Answer: Shale gas

Shale gas is natural gas stored within shale formations and typically requires hydraulic fracturing ('fracking') for economic production.

A porphyry copper deposit is characteristically associated with:

Answer: Felsic to intermediate intrusions at convergent plate margins

Porphyry copper deposits form from magmatic-hydrothermal fluids associated with felsic to intermediate intrusions at convergent plate margins.

Which coal rank has the highest carbon content and is considered the best metallurgical coal?

Answer: Anthracite

Anthracite has the highest carbon content (>86%) and lowest volatile matter among coal ranks, making it the highest-rank coal.

The 'reserve-to-production ratio' (R/P ratio) for a mineral or energy resource represents:

Answer: The estimated number of years reserves will last at current production rates

The R/P ratio divides total proven reserves by the current annual production rate, yielding estimated years of supply remaining.

Volcanogenic massive sulfide (VMS) deposits are primarily enriched in which combination of metals?

Answer: Cu, Pb, Zn, Au, Ag

VMS deposits are polymetallic, characteristically enriched in copper, lead, zinc, gold, and silver.