LESSON 5_ MINING Flashcards
Material that can be used as resource
Mineral Resources
Concentration of a mineral that is of scientific or technical interest
Mineral Occurence
Mineral occurrence of sufficient size and grade or concentration to enable extraction under the most favorable conditions
Mineral Deposit
- Mineral deposit that has been tested and known to be economically profitable to mine.
- Minerals with economic value are ore minerals
Ore deposit
Minerals often associated with ore minerals, but
which do not have economic value
Gangue minerals
Factors which determine if a mineral is of economic value:
➢ interest in the mineral
➢ size of the deposit
➢ mineral concentration
➢ mineral depth below the surface
➢ market value.
Mineral deposits can be classified on the basis of the mechanism responsible for concentrating the valuable substance.
Examples Include:
1) Magmatic Mineral Deposits
2) Hydrothermal Mineral Deposits
3) Sedimentary Mineral Deposits
4) Placer Mineral Deposits
5) Metamorphic Deposits
Origin of Mineral deposits
Under Origin of mineral deposits
- Formed during crystallization of a magma.
- Host rock can range from ultramafic to felsic.
- There are three primary means of concentrating minerals:
Magmatic Mineral Deposits
Under Magmatic mineral deposits
What are the three primary means of concentrating minerals?
a. gravitational settling
b. differentiation
c. immiscible separations
three primary means of concentrating minerals
As minerals crystallize from a magma body, heavy minerals may sink to the bottom of the magma chamber and othersmay form on the sides of the magma chamber.
Gravitational setting
three primary means of concentrating minerals
Causes a concentrating effect resulting in a concentration of selected elements in the residual magma. These elements are the ones which did not fit well inside of common rock forming minerals. Instead they become included in the final liquid present, which forms pegmatite.
Differentiation
three primary means of concentrating minerals
- A variety of igneous rock with extremely large crystals. Individual crystals can be as large as a bathtub.
- Are the last rocks to crystallize from a solidifying body of magma. The slow rate of cooling and the presence of large amounts of water dissolved in the magma account for the large size of the crystals.
- Are an important source for rare elements,
such as boron, beryllium, and lithium.
Pegmatite
- Physical separation of a portion of a magma.
- Immiscible melts form irregular shaped segregations or may be injected as a dike into previously crystallized material.
Immiscible separations
- Minerals concentrated by hot fluids flowing through fractures and pore spaces in rocks.
- Produced when groundwater circulates down to depths and heats up, either by coming near a hot igneous body or by circulating to great depths which naturally heat the water.
- Such hot water can dissolve valuable minerals as it passes through a large volume of rock.
Hydrothermal Mineral Deposits
Under Magmatic mineral deposits
- Formed when heavy metals are mechanically concentrated by flowing surface waters depositing high density minerals either in streams or along coastlines.
- When the velocity of the water slows, minerals with a higher density are deposited.
- Heavy minerals like gold, diamond, and magnetite will be concentrated in areas where water current velocity is low.
- The lighter minerals (quartz) are carried away.
➢ Examples: Gold, Platinum, Diamonds
Placer deposits
Under placer deposits
Placer deposits can occur in any area where current velocity is low such as…
- between ripple marks
- on the inside of meandering streams
- behind rock bars
- in holes on the bottom of a stream
Under Magmatic mineral deposits
- These deposits often form as a result of chemical weathering in warm tropical climates that receive high temperatures and high amounts of rainfall which produces highly leached soils rich in both iron and aluminium. Chemical weathering tends to remove the soluble materials, leaving the less soluble residues.
- Two common mineral deposits formed in this way are iron-rich Limonite and aluminium-rich Bauxite. Bauxite is the world’s primary source of aluminium. It forms in rainy tropical climates from chemical weathering.
- In addition, an existing mineral deposit can be turned in to a more highly concentrated mineral deposit by weathering in a process called secondary enrichment.
Secondary enrichment (Sedimentation)
Under Magmatic mineral deposits
- Many of the most important metamorphic ore
deposits are produced by contact metamorphism.
Metamorphic deposits
Under metamorphic deposits
Are metal-rich deposits in Carbonate rocks that has undergone contact metamorphism.
Skarns
