A modern core logging workflow moves drill core from the rig to a structured documentation process where geologists record rock type, structure, mineralisation, and sample intervals in a systematic sequence. The workflow typically covers core reception, orientation, photography, geological description, geotechnical assessment, sampling, and data entry. How thoroughly each step is carried out directly shapes the quality of exploration decisions downstream.
The exact sequence varies depending on project type, deposit style, and whether logging is done manually or digitally, but the fundamental stages remain consistent across mineral exploration projects worldwide. The sections below break down each part of the process in detail.
What are the key steps in a core logging workflow?
The core logging workflow follows a defined sequence: core reception and tray organisation, core orientation, photography, geological and geotechnical logging, sample interval marking, cutting or splitting, and data entry. Each step builds on the previous one, so skipping or rushing any stage creates gaps that are difficult to recover later.
When core arrives from the drill rig, it is placed into trays in the correct downhole order and labelled with depth intervals. The core is then oriented where possible, using orientation marks made at the rig, so structural measurements can be referenced to true geographic directions. Photography follows, creating a permanent visual record before any cutting or sampling disturbs the core.
Geological logging comes next, where a geologist works along the core tray by tray, recording lithology, alteration, mineralisation, structure, and recovery. Geotechnical parameters such as RQD (Rock Quality Designation), fracture frequency, and joint conditions are noted at the same time on many projects. Once logging is complete, sample intervals are marked, and the core is cut or split for assay. All observations are then entered into a database, either in real time using digital tools or transferred from paper field sheets.
What equipment and tools are used during core logging?
Core logging requires a combination of physical tools and recording equipment. The most important physical tools include a geological hammer, hand lens, acid bottle for carbonate testing, ultraviolet lamp for fluorescent mineral identification, and a compass clinometer for structural measurements. A core logging table is the central workspace where all of this activity takes place.
A well-designed core logging table and equipment makes a significant practical difference. Adjustable, inclined roller tables allow geologists to rotate and reposition core easily without lifting heavy trays, reducing both physical strain and the risk of disturbing core orientation. Integrated components such as photography stations, laptop desks, and core orientation racks allow the full logging sequence to happen at a single workstation rather than moving core between separate areas.
Other tools include sample bags, permanent markers, depth tags, and core saws or splitters for sample preparation. Digital devices such as tablets or ruggedised laptops running geological database software are increasingly standard, particularly on projects where data needs to be validated and shared quickly.
How does digital core logging differ from manual logging?
Digital core logging replaces paper field sheets with database software entered directly at the logging table, eliminating the transcription step between observation and record. This reduces data entry errors, speeds up validation, and makes data immediately available to project geologists, managers, and remote stakeholders.
Manual logging relies on handwritten notes that are later typed into a database, which introduces a second opportunity for errors and adds time to the workflow. It can also make real-time quality checks harder to perform, since supervisors cannot review data until sheets are submitted and entered.
Digital systems offer structured data entry with drop-down menus, mandatory fields, and built-in validation rules that enforce consistency across the logging team. Integration with photography systems means images are automatically linked to depth intervals in the database. The trade-off is that digital setups require reliable power, suitable hardware at the logging station, and staff who are comfortable with the software. For projects using electrically adjustable logging tables with integrated laptop desks and photography stations, digital logging fits naturally into the workstation design.
Who carries out core logging on a mineral exploration project?
Core logging is carried out by geologists, typically with support from geological technicians for sample preparation and handling tasks. The lead logger on a project is usually a qualified geologist with experience in the deposit type being investigated, since accurate lithological and mineralogical interpretation depends on geological knowledge.
On larger projects, a logging team may include a senior geologist responsible for quality control and interpretation, junior geologists or geological technicians handling routine logging and data entry, and a dedicated sample processing team managing core cutting, bagging, and dispatch. Geotechnical logging for civil or mining engineering purposes may involve a geotechnical engineer rather than an exploration geologist.
The skill level of the logging team matters enormously. Consistent terminology, accurate contact placement, and reliable structural measurements all depend on the experience and training of the people doing the work. This is why many exploration companies bring in specialist geological facility planning services for logging, particularly when internal resources are stretched or when a project requires specific deposit expertise.
What data is recorded during geological core logging?
During geological core logging, the data recorded typically includes lithology (rock type), grain size, texture, colour, alteration type and intensity, mineralisation type and estimated abundance, structural features such as veins, faults, and foliation, and core recovery. Geotechnical parameters like RQD and fracture frequency are also recorded on many projects.
Each observation is tied to a specific depth interval, allowing the dataset to build a continuous downhole record of the geology. Structural measurements taken with a compass clinometer are recorded as dip and dip direction relative to the core axis, and corrected to geographic coordinates once core orientation data is applied.
Additional data often captured includes:
- Specific gravity measurements for density modelling
- Magnetic susceptibility readings
- Colour codes using a standard reference chart
- Weathering grade
- Sample interval start and end depths
- Notes on drilling disturbance or core loss
The completeness and consistency of this dataset determines how useful the core data is for resource estimation, geological modelling, and mine planning.
How does core logging quality affect exploration decisions?
Core logging quality directly affects every decision made from drill data, including whether to continue drilling, where to locate the next hole, how to interpret geological contacts, and ultimately whether a resource estimate is reliable. Poor logging introduces uncertainty that compounds through every stage of project development.
Inconsistent lithological descriptions make it difficult to correlate geology between holes, which undermines 3D geological modelling. Missed or misidentified mineralisation can lead to incorrect sample intervals, meaning assay results do not represent the mineralised zone accurately. Errors in structural measurements affect the interpretation of deposit geometry, which influences mine design.
Quality logging depends on three things working together: skilled geologists with relevant experience, a well-organised core logging facility that supports efficient and accurate work, and a data management system that enforces consistency and flags anomalies. The physical workspace matters more than it is often given credit for. A properly equipped core logging facility with purpose-built logging tables, good lighting, integrated photography, and ergonomic design reduces fatigue and distraction, which directly supports the concentration required for accurate observation over long logging shifts.
At Palsatech, we design and supply core logging tables and complete core logging facilities built specifically for this kind of work. Our adjustable inclined roller tables, electrically adjustable logging tables, and ball bearing tables are made from durable materials designed for the demands of core logging, with integrated photography stations, laptop desks, and orientation racks that support a seamless workflow from core reception to data entry. We also offer logging facility planning services to help you configure a space that works efficiently for your team and project scale. If you want to talk through what your project needs, we are ready to help.