JNTU B.Tech III MINERAL EXPLORATION Previous Question Paper (November/December - 2020 - R16)

Prospecting is the systematic process of searching for mineral deposits. It is conducted in sequential stages, moving from broad regional assessments to detailed site-specific evaluations to minimize economic risk.

The primary stages of prospecting include:

1. Regional Reconnaissance: This initial phase involves large-scale surveys covering vast areas to identify favorable geological environments. Methods include remote sensing, satellite imagery analysis, and regional geological mapping to delineate potential mineralized belts or provinces.
2. Detailed Prospecting: Once a target area is identified, exploration intensifies. This stage involves systematic geological mapping, geochemical sampling (soil, stream sediment, or rock chip), and geophysical surveys (magnetic, electromagnetic, or gravity) to narrow down the location of potential ore bodies.
3. Anomaly Evaluation: This stage focuses on verifying the anomalies detected during detailed prospecting. It involves trenching, pitting, and shallow drilling to expose the bedrock and determine the continuity and grade of mineralization near the surface.
4. Exploratory Drilling: This is the most critical stage for subsurface evaluation. Diamond or percussion drilling is employed to extract core samples. These samples are analyzed to determine the depth, thickness, geometry, and grade of the ore body, allowing for the initial estimation of mineral resources.
5. Feasibility and Economic Assessment: The final stage involves calculating the mineral reserves based on drilling data. This includes metallurgical testing to determine recovery rates and economic studies to assess the viability of mining the deposit under current market conditions.

Each stage acts as a filter; if a prospect fails to meet economic or geological criteria at any point, the project is typically abandoned to prevent unnecessary expenditure.

Prospecting is the systematic process of searching for mineral deposits by identifying surface or subsurface indicators. The methods are broadly classified into direct and indirect techniques based on the nature of the evidence gathered.

1. Geological Prospecting: This is the fundamental method involving the study of surface geology. It includes mapping lithological units, identifying structural features (faults, folds, joints) that control mineralization, and examining outcrops for mineral signs. Geologists use field observations to infer the presence of ore bodies based on rock types and alteration zones.

2. Geochemical Prospecting: This method relies on the detection of anomalous concentrations of chemical elements in surface materials. It involves systematic sampling and analysis of:

• Soil and stream sediments to trace dispersion halos.
• Vegetation (biogeochemical) to detect elements absorbed through root systems.
• Water (hydrogeochemical) to identify dissolved mineral content.

3. Geophysical Prospecting: This involves measuring physical property contrasts between ore bodies and the surrounding host rock. Key techniques include:

• Magnetic Method: Detects variations in the Earth's magnetic field caused by magnetic minerals like magnetite.
• Gravity Method: Identifies density differences between dense ore bodies and lighter country rock.
• Electrical/Electromagnetic Methods: Measures differences in electrical conductivity or resistivity, useful for locating sulfide deposits.
• Seismic Method: Uses shock waves to map subsurface geological structures based on wave velocity changes.

4. Remote Sensing: Utilizes satellite imagery and aerial photography to identify large-scale geological features, lineaments, and spectral signatures of alteration minerals that are not easily visible from the ground.

5. Pitting, Trenching, and Drilling: These are direct methods used to verify findings from other techniques. Pitting and trenching involve excavating the surface to expose bedrock, while drilling provides core samples from depth, allowing for the precise determination of ore grade, thickness, and continuity.