Guide to Mineral Exploration
Guide to Mineral Exploration
- One of the target of a Geologist, to find new ore deposits and to define their extent and metal content (grade).
- The geologist has to ensure that the deposit is economically viable and there is a guarantee of ore production over a sufficiently long period of time.
- Even after production starts. It is necessary to locate and delineate any extension to the mineralization.
Now, before dealing with exploration part, we will know about,
more or less synonymous term of Exploration, which is prospecting.
PROSPECTING
- Prospecting involves searching a district for mineral deposits with the view to mine it at a profit.
- The initial signs of potentially significant mineralization are called “prospects”.
- Prospects are the basic units with which exploration geologist work.
- The skill of a successful prospecting involves activity, observation, knowledge, insight, persistence, thinking and luck.
Exploration
- Exploration is the term used for systematic examination of a deposit.
- It is an advance stage of prospecting.
- It involves the determination of exact dimensions, shape, quality, position, characteristics and reserves of deposits.
- Exploration is the qualitative as well as quantitative determination of deposits.
Exploration Processes
- Exploration activity is largely conducted by geologists and geophysicists, assisted by field samplers, drillers, and laboratory personnel (for chemical assays) etc.
- Geological reconnaissance and surface geochemical sampling prevail in the earliest stage.
- Simultaneously or afterwards, geophysical surveys are typically conducted.
- Following surface exploration, the project moves into the drilling stage.
- After this drilling stage, extensive, close-spaced drilling (called “development drilling”) is conducted if fruitful result obtained in earlier stages of drilling.
- Finally, if good results, then “reserve drilling” is conducted, which makes the final assessment of the deposit before actual mining begins.
- Generally, some amount of drilling will continue throughout the life of the mine, as further definition is required and new information is obtained and used to refine the deposit model.
Geological Method
- Geological methods rely on the identification of rocks and minerals and an understanding of the environment in which they formed.
The method includes:
- Geological Mapping (regional and large-scale).
- The technique provide geological maps to exploration agencies or companies with regional geological and geophysical information so that target areas that are conceded to have a better prospect in terms of mineral deposits may be identified.
- To prepare these maps needs of Geological surveys, aim to find what rock types occur at or close to the surface and how these rock types are related to each other i.e. their boundaries, ages, and structure.
Based on known "environments for mineralization" or models for
mineralization, regional geological surveys can be used to define
smaller areas in which more detailed studies can be undertaken.
Geochemical Method
- Geochemical methods involve the measurement of the chemistry of the rock, soil, stream sediments or plants to determine abnormal chemical patterns, which may point to areas of mineralization.
- Chemical analysis in terms of Major and Trace elements.
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Remote Sensing
- This term generally refers to the use of aerial sensor technologies to detect and classify objects on Earth.
- For any geological mapping programme making use of remote sensed imagery, image interpretation represents the ideagenerating, control and planning phases of that programme.
- Aerial Photographs and Satellite images of earth use for interpretation of characteristic features of Earth.
Geophysical method
- Geophysics uses physical methods to measure the surface properties of the Earth. Examples include density, magnetism and electrical properties.
- The measured properties data are then interpreted to give information about the presence of mineral deposits and other geological information.
Drilling
- Drilling is the process whereby rigs or hand operated tools are used to make holes to intercept an ore body.
- Drilling is the ultimate stage in exploration.
- Drilling is used to obtain very detailed information about rock types, mineral content, rock fabric and the relationships between rock layers close to the surface and at depth.
- Drilling is only used in areas that have been selected as "targets" from geological, geophysical and/or geochemical methods.
The purpose of drilling is;
- To define ore body at depth.
- To access ground stability(geotechnical).
- To estimate the tonnage and grade of a discovered mineral deposit.
- To determine absence or presence of ore bodies, veins or other type of mineral deposit.
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