Flashcards in Economic Geology Deck (25)
What are Cu and Al used for?
wire, construction (aluminum)
What is Ge used for?
Semiconductors, transistors, and optics
Where does gold occur?
hydrothermal deposits, placers
Where are lead and magnesium found?
Where do most valuable metals occur?
most occur as atomic substitutions in more abundant rock-forming minerals
Where are most ore minerals found as?
ore minerals such as iron, tin, and tungsten occur as...
non-valuable minerals that metals occur in
Define hydrothermal mineral deposits?
minerals are concentrated by hot aqueous solutions flowing through fractures and pores in the substrate
Define magmatic mineral deposits
Formed by concentration of magmatic processes within a body of igneous
Define sedimentary mineral depostis
formed by precipitation from concetrated, modified sea water
How are placers formed?
Concentration by flowing surface water in streams
or along the shore
How residual minerals deposits are formed
Concentration by weathering processes
What three rules govern the formation of concentrated minerals
rocks or magma
enriched in metals
that can be supplied
to the “
melt or fluid
that can carry
metals from a
source to a site
the metals into
an ore deposit
Where are mineral deposits found?
Mineral deposits are found in a variety of plate
tectonic settings depending on where these
Describe magmatic deposits from gravitational setting
heavy minerals that crystallize early, settle
and concentrate on the bottom of the magma
Some of the most important accumulations of
Associated with magma that forms igneous rocks
Describe magmatic deposits from immiscibility
• segregation of metal-rich (sulphide) liquid from the
• dense, metal-sulfide melt settles to the bottom of
the crystallizing magma chamber
Describe magmatic deposits in pegmatites
Made from melt remaining in last stages of crystalization of granitic magma which is rich in minerals. This liquid flows into cracks and creates large crystals
What are especially reactive carbonate-rich rocks which act as a chemical trap for metals
How are skarns made?
magma flows to marble like rocks, and the minerals are extracted out of the magma into the marble
Describe hydrothermal ore deposits
1. generated from hot water
2. originate from hot, metal-rich fluids
expelled from crystallizing intrusions
3. Fluids move along fractures, cool, and
precipitate the metallic ions to produce vein
Where are vein deposits concentrated?
areas of intense faulting
What are the two most common vein minerals?
quartz and calcite