Alostath

Study on the Suitability of Kikla Gypsum for Industrial Applications

Laila Massaud El-Mazugha, Hatim Abdullah Issa, Mahmoud Al-Wafi, Ziad Sasi — Tue, 28 Jul 2026 00:00:00 +0000

Gypsum deposits are strategically located in populated areas and regions under urban development, benefiting from existing infrastructure, proximity to seaports, and access to energy sources. The most economically significant gypsum deposits in Libya include: Bir Ghanem (estimated reserves of 80 billion tons, purity >95%), Al Jufrah (17 million tons, purity >90%), As Sidrah (25 million tons, purity 84–95%), Al-Rajma (3.5 million tons, purity >97%), and the Kikla area in northwest Libya.

In this study, laboratory tests were conducted on gypsum ore from a newly explored quarry in the Kikla region to determine its purity and industrial applicability. The collected samples were prepared and subjected to a series of standard tests, including fineness, setting time, specific gravity, flexural strength, chemical composition, X-ray diffraction(XRD), and purity assessment. The results showed that Kikla gypsum exhibits favorable physical and chemical properties in accordance with the Libyan Standard Specification No. 51/2005. Specific gravity values ranged from 2.28 to 2.39, and the measured setting times complied with standard limits. Chemical analysis indicated a high SO₃ content (41–46%) with low levels of impurities (SiO₂, Fe₂O₃, MgO), confirming its suitability for the production of construction-grade gypsum as well as certain agricultural applications.

Therefore, Kikla gypsum represents a valuable local resource with significant economic potential, contributing to reduced dependence on imports and creating investment opportunities in Libya’s mining sector, making it suitable for various industrial uses.

The Use of Basalt Rocks in Cement Manufacturing

Abdasalam Mohamed Madi, Mahmoud Bin Mahmou, Walaa Al.Tuwaib — Tue, 28 Jul 2026 00:00:00 +0000

The cement industry is one of the strategic industries that depend on the availability of raw materials and included in its manufacture. In this study, basalt rock was used as a basic component in the cement industry or as a partial substitute for iron and clay, this component works to acquire additional properties of cement in terms of quality and strength. The study showed that the main phase that has an effect on the initial resistance is C₃S tricalcium silicate, responsible for the final strength, while C₃A is responsible for the initial and final doubt time of its interaction with gypsum, C₄AF tetra calcium iron aluminate is responsible for the color of cement and accordingly Libyan and international specifications without exception require that the percentage of dicalcium C₂S be the highest possible to achieve maximum strength after 28 days.

The methodology of the study was to bring large pieces of basalt rock from the field were crushed and grinded and conducted laboratory experiments on them to find out their chemical and mineral components. The study showed that basalt rock contains a good percentage of iron oxide Fe₂O₃, aluminum oxide Al₂O₃, which is close to the components used in the cement industry, from the work of several mixtures to manufacture clinker, the main component of cement, and the results of the analysis of the phases or the four compounds were good, except for the phase of calcium trisilicate C₃S were low, which hurt the early strength decreased, meaning that the initial compressive strength after 3 days was low for cement mixtures containing basalt due to low C₃S, while the compression strength after 28 days for this cement was high and was better than ordinary cement and also had high heat strength.

Feasibility Study of using Marl Raw Material in the Cement industry

Mohamed K Torki, Suleiman Abu-Gharara Al-Raqibi, Ali M Mansour — Tue, 28 Jul 2026 00:00:00 +0000

This study aims to evaluate the suitability of marl as a partial or complete substitute for clay or limestone in cement manufacturing. A detailed chemical and statistical analysis was conducted on a large set of marl samples collected from the Arab Union Cement Factory. Chemical analyses were performed using X-ray fluorescence (XRF) to determine the proportions of major and minor oxides. Several statistical methods—such as standard deviation and coefficient of variation—were applied to assess the variability in marl properties.

The results revealed that the analyzed marl has a chemical composition intermediate between limestone and clay, but with a stronger tendency toward clay-like components. A moderate to high variability was observed in some oxides (such as SiO₂, Al₂O₃, and LSF), indicating a need to enhance homogenization and blending systems within the factory. The study concludes that marl cannot be considered a complete replacement for clay or limestone but is suitable as a complementary component in the raw mix for clinker production, provided that quality control is maintained consistently. The study recommends implementing periodic statistical quality control systems to improve raw material stability and adopting smart control technologies to minimize variability—thereby supporting the production of high-quality cement with lower waste and reduced operational costs.

Evaluation of the Physical and Mechanically Properties of Limestone Rocks in the Shawaa Area and Their Suitability for the Building Materials Industry

Abdsalam Mohamed Madi, Najeeb Abulgasem Al-Sayyah — Tue, 28 Jul 2026 00:00:00 +0000

This study aims to evaluate the physical and mechanical properties of limestone rocks from the Shawa area, located east of Ghadames, Libya, in order to assess their suitability for use in sustainable building material applications. The methodology included the collection of rock samples from the site and conducting laboratory analyses to measure porosity, permeability, density, compressive strength, and tensile strength, in addition to mineralogical and petrographic analyses.

The results revealed that the limestone samples exhibited low porosity and permeability, relatively high density, and compressive strength values ranging from low to medium. Mineralogical analysis showed that calcite is the dominant mineral, classifying the studied rocks as limestone. Based on the findings, the study recommends the potential use of this type of rock in specific applications, particularly ornamental stonework, while emphasizing the need for broader studies covering other locations to validate the results. This research contributes to the ongoing efforts to utilize local geological resources in a more sustainable and efficient manner.

Monitoring Radiation Doses Resulting from Naturally Occurring Radioactive Materials Resulting from Mineral extraction - Oil and Phosphate Extraction as an Example

Ezzeddin Ahmida Al-Ghali — Tue, 28 Jul 2026 00:00:00 +0000

Extracting minerals from the ground results in bringing in other materials that are sometimes unwanted, but their presence is inevitable, among these materials are what are known as Naturally Occurring Radioactive Materials (NORM). In this research, an attempt is made to monitor these materials in two different areas of mineral extraction, which are oil and phosphate. Seven soil samples were collected from the dry or semi-dry surface layer of a number of water collection pits associated with oil production in some Libyan oil fields (Z₁, Z₂, Z₃, Z₄, H₁, H₂ and S₁), and three samples of phosphate fertilizer used in fertilizing agricultural lands in Libya (raw Tunisian fertilizer-F3, raw Moroccan fertilizer-F2 and Tunisian compound fertilizer-F3) and one sample of normal soil for comparison. The radiation detection of these samples was carried out using a gamma ray spectroscopy device with a high purity germanium (HPGe) detector with an efficiency of 40% located in the protection building of the Tajoura Nuclear Research Center. The radioactivity of the samples, a number of hazard indicators and the concentration of emitted radon gas (arithmetic only) were calculated. Sample H₁ (oil) recorded the highest readings, where the radioactivity of 238U, 232Th and 40K was 3.21x10⁵±566.5, 1.46x10⁵±382.9 and 7.44x10³±86.2 Bq/kg, respectively, and an effective equivalent dose (AEDE) of 291.95±17.05mSv/y, while the radon gas flux rate was 65.15±8.07 Bq/m².s. Sample S₁ recorded the lowest readings, where the radioactivity of 238U, 232Th and 40K was 1240±35.24 and 240.5±15.49. 330.05±18.16 Bq/kg, respectively, and an annual effective equivalent dose of 0.96±0.97 mSv/y, while the radon gas flux rate was 0.031±0.17 Bq/m².s.

For phosphate fertilizer samples, significantly lower readings were recorded compared to oil soil samples. The highest readings were recorded for raw Tunisian fertilizer, where the radioactivity of ²³⁸U, ²³²Th, and ⁴⁰K was 267.55±16.35Bq/kg, 3.21±1.79, and 248.9±15.77, respectively. The effective equivalent dose (AEDE) was 0.123 mSv/y, while the radon gas flux rate was calculated as 0.839±0.028 Bq/m².s. When comparing these results, especially for the oil samples, with the results of normal soil samples and the global average for normal soil, was found that these samples are saturated with NORM to the real danger.

Circular economic development scenarios and strategies for the mining sector

Abelfatah Hadi Shibani — Tue, 28 Jul 2026 00:00:00 +0000

This research attempts to explore diverse perspectives on circular economy modeling through structured content covering principles, benefits, challenges, scenarios, and future strategic directions for mining economics. To accomplish this, the research utilized a content analysis approach for the literature and a four-dimensional matrix structure based on the interconnection of two orthogonal axes. Based on the importance of mineral resources within the natural economic resources package, the research addressed the issue of developing mining economies by transitioning from a linear, waste- and emissions-intensive economic system to a circular, low-waste, zero-emission economy. It highlighted the implications of the circular economy for mining and clarified the essence of the 3Rs principle. The research findings conclude that the mining industry is a cornerstone of global economic development, providing essential raw materials for construction, manufacturing, and technology. However, its environmental footprint and linear management have raised concerns about sustainability and the increasing scarcity of resources. It is a transformative approach that seeks to reduce waste, maximize resource efficiency, and create closed-loop systems. It can positively transform how mining resources are extracted, processed, and reused in a way that promotes long-term economic sustainability by considering waste as an economic resource. Accordingly, the research provides models of practical insights and examples that can be used to build scenarios, options, and strategies to guide professionals and investors in mining resources towards sustainable economic development.

The Role of Hybrid Power Systems in Achieving Sustainability in Mining Operations

Abdullah Salem Al-Mashriqi, Milad Faraj Al-Serat — Tue, 28 Jul 2026 00:00:00 +0000

The reliance on diesel generators in remote or off-site mining operations presents environmental and economic challenges stemming from carbon emissions and price volatility. This study aims to address these challenges by highlighting the role of hybrid energy systems in achieving sustainability in mining. A case study approach was employed to explore complex phenomena within the mining sector. Two case studies from Australia and Chile were analyzed using thematic analysis to identify performance factors, challenges, and success factors. The analysis revealed that high capital expenditures, power outage management, and regulatory gaps are the main obstacles to the widespread adoption of renewable energy. Innovative financing models offer a solution to the problem of high capital expenditures. The results demonstrated the ability of these systems to reduce diesel consumption by millions of liters and decrease carbon emissions by thousands of tons annually, while simultaneously enhancing energy security and system stability. The study confirms that hybrid systems are not merely a supplementary energy source, but a fundamental component of a resilient, low-carbon energy strategy. Strategic integration of solar energy is a necessity, not an option, for achieving sustainability in the mining sector. Future trends point towards deeper integration with battery energy storage, electrification of the mining fleet, and green hydrogen production.

Evaluation of the Phosphorus Content of Wadi al-Shati Iron Ore by Chemical Treatment

Hassan Hawil, Laila Massaud Elmazuga, Muftah Abu Zubaida — Tue, 28 Jul 2026 00:00:00 +0000

The iron deposits are widely distributed in wadi shatti area. Despite the presence of important reserve of iron ores, but up to date this ore has not exploited, due to different causes such as, the lack of infrastructure of roads or railways between wadi shatti and coastal cities. Also the shortage of expertise who can handle detailed study which help to exploit the ore in steel manufactures.

Pervious old study carried by French group and industrial research center in seventies indicated the ore has some impurities such as Phosphorous and sulfur which hindered the process of exploiting the ore with the (Metrix method) approved in the Libyan Iron and Steel Company, Misurata (LISCO), Libya.

This study attempt to treat the impurities using chemical acids such as sulfuric and hydrochloric acids. This study concluded the acids treatment gave promising results.

Mineral Resources and Their Role in Promoting Sustainable Spatial Development in Central and Southeastern Libya

Suleiman Abu-Gharara Al-Raqibi, Yahya Ahmed Al-Fasatwi — Tue, 28 Jul 2026 00:00:00 +0000

The current study is a part of the third generation planning project which aims at the development of the Libyan urban plans. Al-Kaleej region was one of the regions targeted by the project; the region covers an area of about 650,000 square kilometers and includes many urban settlements spread over the central and south-eastern of Libya.

Regional planning aims to develop a frame of reference for the implementation of State policies and strategies for sustainable human development at the regional level, as regional planning is considered the base foundation for economic development, the distribution of populations and land uses and future estimation of natural resources including minerals needed for settlements stabilization. Different minerals are distributed over the vast area of the region which is predominantly sedimentary. These minerals have been mapped through interactive maps using the techniques of satellite images and geographical information system representing geographical distribution and areas covered by different types of mineral resources. The study also dealt with the analysis of the role of mineral resources in spatial development for the region; especially the role of minerals used in the manufacturing of construction.
Digital maps were produced using geographical information systems representing the locations and areas of various mineral resources including; limestone, calcarenite, diatomite construction sand, gypsum, salts, sulfur and precious stones.

Sabkha Soil and the Service Life of Flexible Pavement

Entsar Ali elghali, Huda Younes Alidresy — Tue, 28 Jul 2026 00:00:00 +0000

Studying the geotechnical property of sabkha soils and gives a good background for the most appropriate design for that soil, especially that most of the roads that have been rehabilitated during the past few years quickly reached an advanced level of deterioration in the state of flexible pavement. The current study included studying the geotechnical properties of the soils of this region by conducting laboratory tests and determining some of the geotechnical properties of that soil. It was found that the study area is characterized by (SP-SM) sand with silt (Poorly graded) soil, which contains silt, and which is classified as a soil with no plasticity, containing gypsum. the results were presented in special tables and analysis of flexible paving under structural and environmental organelles and it became clear from the data obtained that the increase in axial weights caused a decrease in the age of the road the study concluded with a number of recommendations, the most important of which was the study of the geotechnical properties of the surface layers of the selected sabkha soils and the prediction of rutting pavement life.

An Economic Study of Al-Zlaf Sand and Its Potential for Spatial Development in Southern Libya

Enas Elmonje Eljawini, Mohamed Khalid Torki — Tue, 28 Jul 2026 00:00:00 +0000

Zlaf sand is one of Libya’s most important mineral resources that has not been fully exploited. It is located in the southern region, where vast areas of sand with high silica purity extend. These sands are distinguished by their chemical and physical composition, which makes them suitable for many modern industries, placing them among the strategic raw materials necessary for diversifying the Libyan economy and reducing dependence on oil.

Geological studies indicate that Zlaf sand constitutes a massive resource capable of supporting the mining sector and manufacturing industries for many years to come. Furthermore, its presence in the south offers the region a genuine opportunity to establish industrial projects and infrastructure that support spatial development and provide extensive job opportunities.

A Study of Gezzar Dolomite in Al-Khums Area

Huda Amin Sherif , Refai Taher Refai — Tue, 28 Jul 2026 00:00:00 +0000

This project is a study of the Gezzar dolomite in the study area which is located near Neggazah 18 km west of Al Khums town. The study area comprises two quarries, the first quarry is 1 km west of Neggazah, just south of the coastal highway, and the second one is 2 km southwest of Neggazah. From these two outcrops sixteen rock samples were taken. From these samples lithologic, petrographic and mineralogical studies were collected using petrographic microscope, XRD and SEM. Meanwhile the objective of this study is trying to know the origin of Gezzar dolomite and its difference with the Ayn Tobi member. Besides the economic importance of both Gezzar dolomite and Ayn Tobi member. Petrographic studies using the polarizing microscope and the scanning electron microscope revealed that the Gezzar dolomite is devoid of any gypsum and anhydrate. In this manner we would say that the Gezzar dolomite is Dorag dolomite rather than evaporative dolomite. Moreover, petrographic studies showed that this dolomite consist mainly of dolomite rhombs with a few calcites and aragonite. This dolomite has intercrystalline, vugy, and channel porosities. With regard to the differences between Gezzar dolomite and Ayn Tobi member field and lab evidences showed that the Gezzar dolomite consists mainly of thick to medium bedded gray and hard dolomite. While the Ayn Tobi member consists of dolomitic limestone, these dolomite beds are thick and almost barren of fossils when compared with Ayn Tobi member. Stratigraphic location showed that this dolomite was deposited earlier than Ayn Tobi member. This is simply because as we go up eastward towards Neggazah we find Ayn Tobi outcrops. Economically, the Gezzar Dolomite is an excellent source of pure Magnesium, temperature control in iron smelting plants, and the hardness of this dolomite makes it suitable for masonry and it’s also used as crushed stones in building and highway constructions.

Comparison between Destructive (DT) and Nondestructive (NDT) geophysical techniques for Site Classification and Preliminary Soil Amplification (NEHP)

Faraj M. Eljabri — Tue, 28 Jul 2026 00:00:00 +0000

The main target of this study is to obtain the National Earthquake Hazard Reduction Program (NEHRP) for soil classification using nondestructive geophysical technique, and then to compare with Down hole seismic technique (DHS) as destructive one which has been done before at the same location. Multichannel analysis of surface waves (MASW) as a nondestructive geophysical technique survey has been carried out at a borehole site ILC-11. Borehole Latitude and longitude coordinates are: 90.1653, 38.64, at Mississippi River Bridge (the east of St. Louis) within the new Madrid seismic zone (NMSZ) in the Granite City 7.5’quadrangle in southwestern of Illinois. The study has obtained the primary wave velocities (vp) and shear-wave velocities (vs). Down-hole seismic technique (DHS) as a destructive technique showed a very closed results comparing with multichannel analysis of surface waves (MASW) technique. Survey has given the same soil type according to the (NEHRP) which means that, (MASW) method is an effective tool with great potential for soil classification applications.

UTILIZING QUARTZ SAND IN THE SILICON SOLAR CELL INDUSTRY: AN ASSESSMENT OF EOLIAN SAND IN SEVERAL AREAS IN LIBYA

Osama Rahil Shaltami, Abobakar E. Algomati — Tue, 28 Jul 2026 00:00:00 +0000

In the silicon solar cell industry, silicon is a crucial component. There are three types of silicon solar cells: monocrystalline, polycrystalline, and amorphous. The goal of this study is to propose applications for Libyan eolian sand in the silicon solar cell industry. Twelve areas in Libya were chosen (Sabkhat Ghuzayil, Bir Zaltan, Abu Naim, Al Fuqaha, Sabha, Tanahmu, Awbari, Qararat Al Marar, Hamadat Tanghirt, Bir Anzawa, Tikiumit, and Anay sheets). Based on the publications, we believe that this is the first study looking at solar cell manufacturing in Libya. Previous studies focused on the design, operate and cost of solar cells in Libya. The results showed that the studied sands are rich in SiO₂ (73.62-98.43%), which indicates the possibility of using these sands in the manufacture of silicon solar cells.

Geological Assessment of Mining Potential in Upper Cretaceous-Lower Paleocene Deposits: A Case Study of the Bani Walid Area, Northwest Libya.

Reyadh Alshaybhani Khalefah Atabeeb , Zinab mubark mohammed issa — Tue, 28 Jul 2026 00:00:00 +0000

A geological assessment of the mining potential in the Upper Cretaceous to Lower Paleocene deposits of the Bani Walid area, northwest Libya, was conducted, focusing on the Mizdah Formation (comprising the Qasr Tigrinnah, Mazuzah, and Thala Members) and the Zmam Formation (including the Lower Tar Marl, Upper Tar Marl, and Had Limestone Members). The evaluation combined field studies, collection of 20 representative rock and sediment samples, petrographic analysis, and geochemical testing. Results indicate that the thick, well-bedded limestones of the Mazuzah Member and the gypsum-rich sequences of the Thala Member hold significant potential for use as construction materials and industrial minerals. Additionally, localized occurrences of Celestite (strontium sulphate) within the Zmam Formation suggest possible niche mineralization. However, previously reported phosphate deposits were not substantiated by radiometric and chemical analyses. The study concludes that while limestone and gypsum extraction is feasible, no economically viable deposits of phosphate or metallic minerals were identified. These findings, grounded in a detailed understanding of the stratigraphy and depositional environments, provide a basis for sustainable resource development in north western Libya, effectively linking geological assessment with practical mining applications.

Enhancing geological and structural mapping and identifying mineralization potential in the Tibesti Region through advanced remote sensing techniques

Abdalraouf S. Bouzrida, Khalifa Eldursi , Essam Saeid, Osama Elsherif — Tue, 28 Jul 2026 00:00:00 +0000

This study investigates the geological framework and mineralization potential of the Tibesti region in southern Libya using advanced remote sensing techniques, with emphasis on areas that remain inaccessible due to security constraints. Multispectral Landsat-9 OLI data were processed through a series of atmospheric, radiometric, and noise-reduction corrections to enhance spectral accuracy. Band ratios, False Color Composites (FCC), and Principal Component Analysis (PCA) were applied to identify key alteration minerals, particularly iron oxides and Al-OH–bearing clay minerals such as kaolinite, illite, and montmorillonite, which serve as indicators of hydrothermal alteration. Supervised classification using reflectance signatures derived from the geological map of northern Chad enabled the extension of geological mapping into poorly studied northern Tibesti, confirming continuity of major lithological units including Cambro-Ordovician and Devonian sandstones, granodiorite, and Nubian Sandstone.

Structural analysis incorporated hill shade models and enhanced band composites, allowing the delineation of major fault and fracture systems. Manually extracted lineaments were used to generate a fault-density map, revealing structurally intense zones closely associated with intrusive bodies. Integration of structural data with hydrothermal alteration mapping demonstrates significant overlap between high-density fault zones and clay alteration belts, identifying priority targets for mineral exploration. Correlation with known illegal gold-mining sites further validates the remote sensing results and highlights the region’s mineral potential.

Keywords: Remote sensing, geological mapping, Lineament analysis, Minerals exploration, Landsat-9, machine learning classification.

Using Igneous Dikes as Alternatives to Iron Ore and Pozzolana in Cement Production.

Majed Mohammed Al-Hatheq — Tue, 28 Jul 2026 00:00:00 +0000

The cement industry is a fundamental pillar of urban development, yet it faces increasing challenges related to resource sustainability and the cost of traditional raw materials. This study aimed to evaluate the geological and chemical potential of Igneous Dikes as an alternative source for both iron ore and pozzolana in cement production. The methodology involved analyzing the chemical composition of the igneous dikes using X-ray Fluorescence (XRF) and comparing them with traditional pozzolana. Five different cement mixtures were prepared, including a reference mix, and mixes containing 8% pozzolana or 8% igneous dikes, with or without the addition of 2% black limestone.

The compressive strength of the resulting cement cubes was tested after 3, 28, and 90 days. The results demonstrated that the iron-rich igneous dikes contain suitable concentrations of ferric oxide (Fe₂O₃), which contributes to maintaining the required chemical composition of the clinker, particularly the ratio of tetra calcium aluminum ferrite (C₄AF), thereby reducing the reliance on traditional iron sources.

Furthermore, the chemical composition of the igneous dikes was found to be very similar to that of traditional pozzolana, reflecting their common volcanic origin. Most importantly, the mixes containing igneous dikes showed higher compressive strength at all ages compared to similar pozzolana mixes.

For instance, the mix containing 8% igneous dikes and black limestone achieved a compressive strength of 34 MPa after 3 days and 67 MPa after 90 days, surpassing the performance of the similar pozzolana mix (32.1 MPa and 63 MPa, respectively). The study concludes that igneous dikes represent an effective, economically, and environmentally feasible alternative to both imported iron ore and pozzolana. Their utilization contributes to enhancing the sustainability of the cement industry by leveraging local resources while maintaining, and in some cases improving, the final product's quality and compressive strength.

Excavability Assessment of Carbonate Rock Masses in the Tarhuna Area, Northwest Libya

Mahmud A. Al Tarhouni , Zakaria M. Aboumonji — Tue, 28 Jul 2026 00:00:00 +0000

Effective assessment of rock mass excavatability is a mandatory requirement for the strategic planning and economic control of civil and mining engineering works such as road cuts, trenches, quarries and open excavation. This study presents an assessment of rock mass excavatability in the Tarhuna area, northwestern Libya, located southeast of Tripoli. The study’s main objective was to design excavation methods for rock masses and estimate their excavability using multiple established geoengineering classification systems. The geology of the study area consists of the Sidi as sid Formation (the Ain Tobi Limestone and Yafrin Marl members). The methodology involved extensive field work, including the drilling of exploration boreholes. Laboratory testing was performed on rock samples to determine key geotechnical properties, including the Unconfined Compressive Strength (UCS), Point Load Index (Is), and core quality parameters such as Total Core Recovery (TCR), Solid Core Recovery (SCR), and Rock Quality Designation (RQD). Rock mass characterization was achieved through established systems, specifically the Rock Mass Rating (RMR) and the Tunnelling Quality Index (Q-System).

Excavatability was assessed using the Franklin method, the Excavatability Index (N-Index) and the Rip ability Rating (RR). The results indicated that the rock masses in the Tarhuna area generally require “very hard ripping,” which suggests that heavy-duty machinery or pre-blasting techniques may be necessary to increase production and penetrate the rock mass economically.

The study also demonstrates empirical alignments between the rock mass classifications and excavability assessment methods, adopting an integrated, multi-methodological geoengineering approach yields a significantly more accurate, well-calibrated, and balanced assessment of rock mass excavatability.