Field sampling and core processing are two distinct stages of mineral exploration work. Field sampling collects surface or near-surface material from an area of interest, while core processing handles the systematic preparation and analysis of drill core extracted from depth. Both methods generate geochemical and geological data, but they serve different purposes at different points in a project’s lifecycle.
Understanding where each method fits helps exploration teams make smarter decisions about budget, timing, and the quality of data they need. The sections below break down how each method works, how they compare, and when to use one over the other.
What does field sampling involve in mineral exploration?
Field sampling in mineral exploration involves collecting rock, soil, sediment, or water samples directly from the surface or shallow subsurface of a target area. It is typically one of the first steps in exploration fieldwork, used to identify anomalies, map geology, and decide where to focus further investigation.
Common field sampling techniques include:
- Rock chip sampling: Collecting fragments of outcropping rock to identify mineralisation at the surface
- Soil sampling: Gathering soil at regular grid intervals to detect geochemical halos from buried deposits
- Stream sediment sampling: Using drainage systems to trace mineralisation upstream
- Trench sampling: Cutting into shallow ground to expose and sample fresh rock along a defined line
The goal of exploration fieldwork at this stage is reconnaissance. Teams cover large areas efficiently, gathering enough data to prioritise targets without committing to the cost of drilling. Sample collection protocols, labelling, and chain of custody documentation are all important at this stage because poor field practices can compromise every downstream analysis.
What is core processing and what does it include?
Core processing is the systematic handling, description, and preparation of drill core samples after they are retrieved from a borehole. It transforms raw drill core into documented, analysed material that provides reliable information about the geology, mineralogy, and geochemistry at depth.
Core processing typically includes:
- Core logging: Systematic geological description of rock type, structure, alteration, and mineralisation along the core
- Core photography: Standardised photographic documentation of core trays before and after sampling
- Core cutting and splitting: Sawing or splitting core to prepare representative halves for analysis
- Sample preparation: Crushing, pulverising, and splitting material to produce a homogeneous sample for laboratory submission
- Quality control sampling: Inserting blanks, duplicates, and certified reference materials to monitor analytical performance
Core processing services require dedicated facilities with appropriate equipment, trained personnel, and strict procedural controls. The quality of this work directly affects the reliability of resource estimates and, ultimately, investment decisions.
How do field sampling and core processing differ in purpose?
Field sampling and core processing differ primarily in their purpose and the stage of exploration they serve. Field sampling is a targeting tool used early in a project to identify where mineralisation may exist. Core processing is a characterisation tool used later to define what the mineralisation looks like, how thick it is, and what grade it carries.
Field sampling answers the question: where should we drill? Core processing answers the question: what did we find when we drilled there?
This difference in purpose also shapes the type of data each method produces. Field samples generate broad geochemical patterns across an area. Core samples generate detailed vertical profiles through a deposit. The two datasets are complementary rather than interchangeable, and most projects need both at different points in time.
Which method produces more reliable geochemical data?
Core processing generally produces more reliable geochemical data than field sampling because drill core is a controlled, representative sample taken from a known depth and location. Surface samples collected during exploration fieldwork are subject to weathering, contamination, and spatial variability that can introduce noise into the data.
That said, reliability in both methods depends heavily on how the work is done. Poorly logged or contaminated drill core can produce misleading results, just as a rigorously collected soil grid can deliver highly predictive geochemical data.
Key factors that affect data reliability include:
- Sample representativeness (is the sample truly reflecting the material at that location?)
- Contamination controls during collection and preparation
- Quality assurance and quality control (QAQC) protocols
- Laboratory selection and analytical method
- Documentation and chain of custody
For resource estimation and feasibility studies, core-based data is the standard because it meets the rigorous requirements of reporting codes such as JORC or NI 43-101. Field sampling data supports earlier-stage decisions where a lower level of certainty is acceptable.
When should a project use field sampling versus core processing?
A project should use field sampling during early-stage exploration when the goal is to identify and rank targets across a large area. Core processing services become relevant once drilling begins and the project needs detailed, depth-specific data to advance toward resource definition.
A typical exploration project follows this sequence:
- Reconnaissance and target generation: Field sampling (soil, rock chip, stream sediment) covers large areas at low cost
- Target refinement: Follow-up field sampling on priority anomalies, combined with geophysics
- First-pass drilling: Core processing begins as drill holes are completed to test the best targets
- Resource definition drilling: Intensive core processing, logging, and sample preparation to support resource estimation
Budget is also a practical factor. Field sampling is significantly cheaper per data point than drilling and core processing. Projects with limited funding often maximise field sampling to identify the single best target before committing to the higher cost of a drill programme.
Can field sampling and core processing be managed as a combined service?
Yes, field sampling and core processing can be managed as a combined service, and doing so has real advantages. When both activities are handled under a single service provider, data flows more consistently, protocols stay aligned, and there is less risk of miscommunication between field teams and processing facilities.
Managing them separately introduces handover points where documentation can become inconsistent or samples can be mishandled during transport and transfer. A combined approach also makes it easier to apply uniform QAQC standards across both stages.
At Palsatech, we offer exactly this kind of integrated support. Our geological and field services cover exploration fieldwork from the earliest surface sampling stages through to full core processing services at our PalsaCenter facilities. Whether you need short-term field support or long-term project management, our geologists and technicians are ready to handle both ends of the workflow so you can focus on the results rather than the logistics.