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 Form 1 Geography Online Lessons on Mining

In this lesson we are going to learn about the formations in which minerals occur

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Answer Text:
- Process of extracting valuable minerals from the earth’s surface.
Formations in Which Minerals Occur
1. Veins and Lodes
- Occurrence of minerals in crevices, cracks or faults in igneous rocks.
• They are said to occur in veins if they occur there in small quantities.
• Said to occur in lodes if they occur there in large quantities e.g. zinc, copper and silver. 2. Reefs
- Veins and lodes which are exposed on the surface.
3. Seams/Layers/Beds
-Occurrence of minerals as sedimentary or as a result of compression of accumulated organic or inorganic material e.g. coal and halite.
4. Alluvial Deposits
-Occurrence of minerals while mixed with materials such as sand, gravel, silt, etc.
-These were minerals which were detached from the veins by weathering and carried away by streams and rivers and got deposited e.g. gold, diamond and platinum.
5. Weathering Products
- Minerals formed by deep weathering of rocks then leaching carried minerals from the top to lower layers where they accumulated e.g. aluminium, nickel, iron and manganese.
6. Oil pools/Wells
-Occurrence of minerals in pools or wells in sedimentary rocks e.g. petroleum and natural gas.
Conditions Necessary for Formation of Petroleum
a) Presence of fossils or organic remains
b) Presence of sedimentary rocks for burying organic remains.
c) Presence of pressure to compress organic remains to cook the oil and natural gas out of organic matter.
d) Presence of a porous reservoir rock to store and transmit petroleum to the oil pools e.g. limestone and sandstone.
e) Presence of a trap like a syncline to hold petroleum in a reservoir to prevent its escape.
f) Presence of impermeable rocks below the trap or syncline to prevent petroleum from percolating further underground.