grabnäytteet

Grabnäytteet (grab samples) are a type of field sample collected by hand from a single location to provide a quick snapshot of the material’s composition. The aim is to obtain a small, non-composite piece that reflects what is present at that spot. In practice, a grab sample is taken with a hammer, chisel, scoop, or trowel from rock outcrops, soils, sediments, or mine waste, and then placed in a labeled container for analysis.

In mineral exploration and geochemical surveys, grab samples offer rapid, qualitative information about mineralization and element concentrations. They help identify zones of interest and map surface variability. However, they are not statistically representative of an ore body due to small size and local heterogeneity, and results are typically used to decide where more systematic sampling, such as trenching, drilling, or bulk sampling, should be pursued.

Collection and handling follow practical guidelines. Sample mass usually ranges from a few hundred grams to several kilograms. Each sample should be clearly labeled with location, depth (if relevant), date, and collector. To avoid contamination, use clean tools and containers, and maintain a chain of custody and field notes, including GPS coordinates or map references.

Quality control is important. Replicate samples, blanks, and certified reference materials help assess analytical accuracy. Grab samples are a useful first step in assessment but must be interpreted with caution and in the context of additional, more representative sampling.

See also: channel sample, bulk sample, drill core.