Soil sampling and rock chip sampling are two early-stage sampling procedures in prospecting. Rock chip sampling typically occurs on outcroppings, or areas of exposed bedrock, while soil sampling will occur in areas where there are no outcroppings, with the goal of sampling mineralization below the surface.
The purpose of soil sampling and rock chip sampling in the mining and exploration industries are to help determine the existence and extent of mineralization in a prospective area. It is typically an early step in the mineral exploration process that will later help to inform drilling exploration.
What is Soil Sampling?
Soil sampling is the process of extracting, labeling, and testing soil to determine its mineral makeup. These tests are used to measure the concentration of certain metals in the soil, helping to infer the existence and extent of mineralization in an area. They may also be used to inform drilling for further investigation. Soil samples are often taken by hand-held augers, handled picks, or garden spades, making the process relatively non-intrusive.
To be effective, soil sampling should be done strategically in an area, with locations chosen based on the increased probability of mineralization’s and at strategic points to reasonably cover the territory. Geologists may use historical mineral occurrences, mapping or prospecting, and geophysical surveys to guide a soil sampling location strategy.
Samples must be consistently labeled using GPS coordinates so data may be accurately attributed to the correct area. It’s also important to avoid cross-contamination, which can occur if jewelry comes in contact with the soil, tools have remnants from previous samples on them, etc.
What is Rock Chip Sampling IN MINING & EXPLORATION?
Rock chip sampling is a process of mineral exploration in which rock chip samples are taken from outcroppings, or exposed bedrock. These rock chips are then sent to a laboratory to determine their mineral makeup to help inform mineralization in the area.
There are different methods of rock chip sampling, each of which has different purposes and varying levels of accuracy.
Chip Sampling. Chip sampling is used in early mineral exploration to determine if an area is of interest. In this process, several small rock fragments are collected over an area using a geologist’s hammer and chisel. These chips are composited into one sample and sent to a laboratory for testing. Typically, a geologist will high-grade this sample, looking for rock chips that have the best chance of containing the sought-after element. This method of testing isn’t used to provide a reasonable representation of the mineral makeup and abundance in the area, but rather to determine whether the area is of interest.
Chip-Channel Sampling. This method of rock chip sampling is used when an interval that should be sampled can be identified in exposed rock. It attempts to define the approximate width and grade of the zone and the adjacent rocks by taking small, contiguous rock chip samples along the channel.
Sawn-Rock Channel Sampling. The most accurate and objective form of rock chip sampling, sawn-rock channel samplings are cut from rock walls of a zone to test any mineralization. This type of sampling is most often used in a mine environment.
Final Thoughts
The use of soil sampling and rock chip sampling are important to the early exploration of a prospective mining area, helping to inform the mineral makeup of an area to determine whether it merits further exploration. For more information about rock chip or soil sampling services, please reach out to Rangefront to speak with an expert.
ABOUT THE AUTHOR
BRIAN GOSS
President, Rangefront Mining Services
Brian Goss brings over 20 years of experience in gold and mineral exploration. He is the founder and President of Rangefront, a premier geological services and mining consulting company that caters to a large spectrum of clients in the mining and minerals exploration industries. Brian is also a director of Lithium Corp. (OTCQB: LTUM), an exploration stage company specializing in energy storage minerals and from 2014 to 2017, he fulfilled the role of President and Director of Graphite Corp. (OTCQB: GRPH), an exploration stage that specialized in the development of graphite properties. Prior to founding Rangefront, Brian worked as a staff geologist for Centerra Gold on the REN project, as well as various exploration and development projects in the Western United States and Michigan. Brian Goss holds a Bachelor of Science Degree with a major in Geology from Wayne State University in Michigan.
This article was originally published in May 2022 and has since been updated for content, relevance, and resources.