Dimension Stone - Exploration and Exploitation in parts of Lokoja, North-Central Nigeria
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-04-23 |
| Journal | Journal of applied science and environmental management |
| Authors | N. Egesi, J.I. Nwosu |
| Institutions | University of Port Harcourt |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThe study provides an engineering-geological assessment of dimension stone prospects in the Lokoja area of North-Central Nigeria, confirming the availability and quality of materials for high-value construction.
- Resource Confirmation: The Lokoja area possesses abundant reserves of commercially viable dimension stone, including granite, marble, granite gneiss, and migmatite, suitable for building and monumental applications.
- Quality Validation: Granite and granite gneiss samples meet stringent international quality standards (BS, ASTM, AASHTO) based on mechanical testing, confirming their durability and suitability for polishing and carving.
- Mechanical Performance: Acceptable rock types demonstrated Rock Strength (RS) values typically ranging from 16 to 26 MPA, with corresponding low Rock Class Factors (RCF) and Swell Factors (SF) (1.12 to 1.2).
- Migmatite Exception: Migmatite samples showed marginal performance, exhibiting a high RS of 36 MPA, RCF of 7%, and SF of 1.25%, exceeding the standard limits established by comparative regional analysis.
- Exploitation Technology: Current mining operations utilize precise and delicate techniques, such as diamond wire saws and belt saws, capable of producing large, high-quality rectangular blocks (observed primary cut width of 1m).
- Economic Potential: The paper highlights that current investment is low-stage, advocating for increased capital and geological oversight to maximize production for local consumption, export, and economic diversification away from the oil sector.
Technical Specifications
Section titled âTechnical SpecificationsâThe following data summarizes the mechanical properties of Lokoja dimension stone samples and comparative standards.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Rock Strength (Granite) | 23 - 24 | MPA | Lokoja Quarries 1 & 3 (Acceptable) |
| Rock Strength (Granite Gneiss) | 26 | MPA | Lokoja Quarry 7 (Acceptable) |
| Rock Strength (Marble) | 16 - 20 | MPA | Lokoja Quarries 2, 4, 6, 8 (Acceptable) |
| Rock Strength (Migmatites) | 36 | MPA | Lokoja Quarry 5 (Above standard limit) |
| Rock Class Factor (RCF) | 4 - 5 | Dimensionless | Acceptable range for most Lokoja rocks |
| Rock Class Factor (Migmatites) | 7 | % | Above standard limit |
| Swell Factor (SF) | 1.12 - 1.2 | Dimensionless | Acceptable range for most Lokoja rocks |
| Swell Factor (Migmatites) | 1.25 | % | Above standard limit |
| Aggregate Abrasion Value (AAV) | < 30 | % | Acceptable Standard Limit (BS, ASTM) |
| Absorption (Biotite-Granite) | 0.54 | % | Comparative data (Boki Area) |
| Absorption (Acceptable Limit) | < 10 | % | Standard Limit (BS, ASTM) |
| Primary Cut Block Width | 1 | m | Dimension stone mining operation |
Key Methodologies
Section titled âKey MethodologiesâThe assessment of dimension stone suitability involved a combination of field surveys, laboratory testing, and observation of current mining practices.
- Geological Survey and Identification: Detailed field mapping was conducted to identify and locate exposed basement complex rocks, including marbles, granites, granite gneisses, and migmatites.
- Petrographic Analysis: Samples were analyzed to determine intrinsic rock quality parameters, including mineralogy, grain size, texture, fabric, and weathering states, which dictate durability and polishing potential.
- Rock Strength Testing: Samples from various quarries underwent mechanical testing to determine Rock Strength (MPA), Rock Class Factor, and Swell Factor, using established procedures (e.g., Total Quality Nigeria Ltd).
- Standard Compliance Check: Test results were compared against known international standards (British Standards (BS), American Society for Testing and Materials (ASTM), AASHTO, and German DIN) to confirm commercial viability.
- Mining Technique Observation: Current exploitation methods were documented, focusing on the use of precise cutting equipment such as diamond wire saws, diamond belt saws, and jet-piecers, necessary for producing dimension stone blocks rather than aggregates.
- Geological Oversight Recommendation: The study emphasized the necessity of involving trained geologists in all phases (Exploration, Evaluation, Production, Research) to ensure quality control, waste minimization, and sustainable resource management.
Commercial Applications
Section titled âCommercial ApplicationsâThe identified and tested dimension stones from Lokoja are suitable for various high-value engineering and construction applications.
- Architectural Cladding and Veneer: Polished granite, marble, and gneiss are ideal for exterior and interior wall cladding, offering high aesthetic appeal, durability, and low maintenance (requiring washing instead of painting).
- High-Durability Flooring: Cut and polished stone (e.g., granite gneiss, migmatite schist) is used for floor tiles in high-traffic commercial and hospitality environments (e.g., Virgin Rose Hotel, Eko Hotels).
- Structural and Monumental Construction: The high strength and resistance to weathering make these rocks suitable for structural support and the creation of long-lasting monuments.
- Aggregate Production: Biotite granite, currently quarried and blasted for aggregates, can be utilized for pavement construction materials, providing a secondary market for lower-grade or waste rock.
- Industrial Feedstock: Marble deposits are utilized as raw material, crushed into powder for use in cement manufacturing.
- Export Market Diversification: The confirmed quality and abundance of granite and gneiss offer significant potential for export, contributing to the non-oil sector economy and creating specialized job opportunities in stone processing.
View Original Abstract
The study area Lokoja is the home to the confluence between Rivers Niger and Benue. Dimension stone is cut or quarried stone in accordance with specific dimensions, generally more abundant and are used in greater quantities than ore minerals in pavement and several other constructional activities. The objective of the paper is to present prospects and a lead of rocks in Lokoja area for the production of dimension stone. The rocks in the area are being quarried as aggregates or mined as dimension stone and they met quality parameters of the rocks which includes, must be durable, easy to quarry, work, cut and polish. The particular stones selected depend upon the local weathering conditions which can be determined by amounts of industrial gases present and availability of the rocks locally. The rocks identified are marbles, granite gneisses, migmatites and biotite granites. The granites are being quarried for aggregates, marbles are powdered for cement production while migmatites and granite gneisses were mined for dimension stone.The results of Rock Strength (MPA), Rock Class Factor and Swell Factor are within acceptable standard limits except for migmatites with RS 36%, RCF 7% and SF 1.25%, which is above the limit when compared with previous analysis of AAV 22.0%, ACV23.3%, AIV18%and Absorption 0.54% in Boki area. The dimension stone were separated by more precise and delicate techniques, such as diamond wire saws, diamond belt saws, in the mine the cut dimension stone width are 1m, while many are rectangular in shape. They occur in the same geologic setting of the basement complex of Northcentral Nigeria. In the area investment has been at relatively low stage more investment will significantly increase production of the dimension stone for local usage, export and economic growth.
 Keywords:Dimension stone, durable, available, maintenance, migmatite, Lokoja