Term
| Economic deposit is one which can be extracted and sold at a profit, but what things affect the probabitlity of mines and quarries? |
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Definition
| How deeply the deposit is buried,How much waste rock has to be taken out. |
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Term
| What is the best way to find economic deposits? |
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Definition
| Search for geological situations similar to those where deposits have already been found. |
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Term
| What quick and cheap methods are used to detect likely spots of economic material? |
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Definition
Regional surveys can be based on:
Seismic Techniques- by sending a series of shock waves produced by small explosive charges through rocks, to collect information about the densities and structures of minerals below
Geochemical Techniques- collecting & analysing small samples of soil, stream water,etc., allows us to discover the concentration of particular elements.
Magnetic Techniques- An area with unusually strong magnetism is likely to be rich in iron. |
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Term
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Definition
| Holes drilled into promising sites, with the help of regional surveys.They remove an undamaged central core of rock to be studied at the surface.They prove if particular deposits are actually presentShow how much of a deposit is there.Indicate any problem that may affect extraction. |
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Term
| When is a deposit economi? |
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Definition
If the value of the deposit is greater than the cost of extraction.
However the value of the deposit varies as the price of the material changes. |
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Term
| Economic minerals can be classified as metallic. What does this mean? |
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Definition
Those mined for their content of metal
e.g iron from haematite. |
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Term
| Economic minerals can be classified as non-metallic. What does this mean? |
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Definition
THE MINOR MINERALS- These are found concentrated in particular areas thanks to certain geological processes.
They are in demand by chemical companies....
e.g Chlorine and caustic soda produced from halite.
...or as raw materials for industry.
e.g gypsum to make plaster. |
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Term
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Definition
| A mineral deposit that can be mined at a profit. |
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Term
| What is a gangue mineral? |
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Definition
| A worthless mineral found with the ore. However, the worth is determined by the economic market at that time. |
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Term
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Definition
| The total body of minerals present; this may include several ore minerals and a number of gangues. |
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Term
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Definition
| A vertical or near verticle body of minerals found infilling a fault or joint. |
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Term
| What is a magmatic deposit? |
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Definition
When economic minerals crystallize directly from magma, and become concentrated in a certain part of the intrusion. During cooling, magnetite, chromite, and nickel ores may crystallise and sink to the bottom of the intusion forming an economic concentration of minerals.
The best examples are the gabbros. These are relatively rich in iron. |
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Term
| What is a hydrothermal deposit? |
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Definition
Deposits formed by hot watery fluids carrying minerals in solution, which crystallise when chemical conditions are suited.Types of deposits produced are:
Veins- as fluid flows along a vein over a period of time, the order in which the crystals are formed occur in a distinct layerNon metallic minerals like quartz, flourite, and calcite, are associated with metallic minerals like lead, zinc, copper, and iron. |
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Term
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Definition
| A vertical or near verticle body of minerals found infilling a fault or joint. |
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Term
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Definition
| Close to granite intrusions. A typical granite magma contains traces of economic elements like lead and copper, and all magma's contain a relatively large amount of water. However, towards the end of the crystallisation of the rock's silicate minerals, all the trace elements become concentrated in the mass of water, which moves up and out into surrounding rocks as a mineralising hydrothermal solution. |
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Term
| How can we justify why veins are found well away from any known batholiths? |
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Definition
When marine sediments are deposited they contain a large amount of brine......the brine becomes heated as the sediments are buried......and because of pressure the hot brine moves up and picks up traces of metallic elements as they pass through the sediments......the minerals crystallise and form veins.
It is the effect of millions of years ao mineral accumilation. |
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Term
| What are sedimentary percipitated deposits? |
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Definition
Sediments formed when water evaporates and and precipitates its dissolved chemiclas.
Only a few sediments are deposited in reasonable amounts. The least soluable chemical is the first to be precipitated, and this in sea water is calcium carbonate, which forms micrite. |
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Term
| How is micrite (Lime mudstone) formed? |
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Definition
| Calcium carbonate in sea water, in warm tranquil areas where evaporation takes place(e.g like a flat shallow bank), tiny crystal of a fine white mud is precipitated called micrite.,li> Sometimes ordinary mud (clay minerals) is deposited with the micrite, giving it a dark grey colour. |
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Term
| What are residual deposits? |
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Definition
| These are a result of intense chemical weathering hot wet climates of tropical land.Weathered materials are removed in solution, though common products of the break down of silicates like iron, aluminium, and hydroxides are very insoluable.Therefore they remain in the soil as residue, deep red couloured compounds.These soils are called laterites. |
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Term
| What are placer deposits? |
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Definition
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