Several methods are employed to collect ore samples, each suited to different stages of exploration and mining, as well as varying geological conditions. The choice of method aims to obtain material that can accurately represent the larger ore body for analysis (OSME, 2018).
- Grab sampling involves collecting rock specimens, often opportunistically, from outcrops, mine workings, or stockpiles to get a preliminary idea of ore grade.
- Chip sampling is a more systematic approach where small rock fragments are chipped from a rock face at regular intervals to assess mineralization.
- Channel sampling provides a more representative sample by cutting a continuous groove of uniform width and depth across a mineralized zone, collecting all the resulting material (DSPMUniv, 2020). This is particularly useful for vein-type or layered deposits.
For subsurface investigation, drilling methods are crucial.
- Diamond drilling retrieves solid cylindrical cores (drill core samples) that offer detailed geological information and are ideal for resource definition (SciELO, 2014)
- Reverse Circulation (RC) drilling produces rock chip samples (cuttings) more rapidly and at a lower cost, often used in open-pit grade control and for defining bulk, lower-grade mineralization (SciELO, 2014).
- Bulk sampling involves extracting a large volume of material (hundreds to thousands of tonnes) for comprehensive metallurgical testing to assess how the ore will behave during commercial-scale processing (OSME, 2018).
Other methods include face sampling from exposed ore surfaces in underground mines (DSPMUniv, 2020).
Which sampling method do you think gives the most reliable results and why? Share your thoughts!
