This set of Engineering Geology Multiple Choice Questions & Answers (MCQs) focuses on “Origin of Ore Deposits”.
1. What is the mineral which contains a metallic element which can be economically exploited called?
a) Ore mineral
b) Metallic mineral
Explanation: Ore mineral is defined as a mineral which contains a metallic element in a quantity that can be exploited and extracted for use at an economical cost.
2. The definition of ore is dependent on
Explanation: Natural concentration of an ore mineral in a massive rock body is defined as an ore deposit. Hence the definition of an ore deposit is also size dependent.
3. The non-metallic minerals associated with ore minerals are called
a) Non-metallic minerals
b) Metallic minerals
c) Gangue minerals
d) Flux minerals
Explanation: A few non-metallic minerals are often found associated with an ore-mineral. These have be separated from the ore before the same is processed for extraction of the metal. These associated minerals are called gangue minerals.
4. How many types of rocks are there on the basis of time of formation?
Explanation: On the basis of their time of formation relative to the host rock, the ore deposits are divided into two groups: syngenetic and epigenetic.
5. The deposits that have formed simultaneously with the enclosing rock are called
Explanation: Syngenetic deposits are such deposits that have formed simultaneously with the enclosing rock. These are either of igneous or of sedimentary types.
6. Deposits that were formed subsequent to the formation of the host rocks are called
Explanation: Epigenetic deposits are those deposits that were formed subsequent to the formation of the host rock. Epigenetic deposits of igneous, sedimentary and metamorphic types are known.
7. The deposits occurring close to the roofs of magmatic masses
a) Magmatic deposits
b) Pegmatite deposits
c) Hydrothermal deposits
Explanation: Pegmatite deposits are sometimes classified as a distinct group of magmatic deposits formed towards the end of crystallization process and such necessarily occurring close to the roofs of magmatic masses.
8. Which of the following is not an essential condition for hydrothermal deposits?
a) Highly active fluids
b) Highly enriched fluids
c) Highly inactive fluids
d) Suitable pathways
Explanation: The three essential conditions for the formation of hydrothermal deposits are: highly active and enriched fluids, suitable pathways for their migration through the rocks, and suitable physic-chemical environment for their deposition to take place.
9. Type of veins which are bodies of tubular shape in pre-existing fissures
d) Stock works
Explanation: Fissure-veins may be defined as mineral bodies of elongated or tabular shape deposited in pre-existing fissures. The original fissures may be parallel or intersecting, radial or fan-shaped in pattern and that is also the shape of the resulting ore bodies.
10. The type of vein commonly found in igneous rocks is
d) Stock works
Explanation: Ladder-veins are commonly found in igneous rocks such as dykes and similar bodies and consist of transverse, roughly regularly spaced fractures that are filled with deposits of economic minerals.
11. Gash-veins are generally found in
a) Silicate minerals
b) Felspar minerals
c) Metallic minerals
d) Carbonate minerals
Explanation: Gash-veins are narrow, sloping and thick-bodies deposits of minerals deposited in solution-fissures or cracks of the host rock which is generally a carbonate rock like limestone.
12. When gravity is the agent of placing of deposit, the deposit is called
a) Deluvial deposit
b) Aeolian deposit
c) Alluvial deposit
d) Beach placers
Explanation: Deluvial placers is the term used when gravity is the agency involved; such placers would be found along the foot hills and talus slopes.
13. The term used for the rock hydrothermal deposits that occur in veins of exceptionally small size, but in good number is
d) Stock works
Explanation: The term, stock works, is used for hydrothermal deposits that occur in veins or fissures of exceptionally small size, but in good number, within a limited space, traversing the body of rock profusely.
14. Magmatic ore deposits do not commonly occur in forms of injective. State true or false.
Explanation: Magmatic ore deposits commonly occur in the following forms: segregations, disseminations and injections.
Sanfoundry Global Education & Learning Series – Engineering Geology.
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