The old adage of garbage in, garbage out has never been more relevant than when dealing with geochemical samples. To capture the most out of your survey there are a few essential items that need to be documented.
Date, Your Name and Sampling Partner(s) Name(s)
No, we're not trying to see how many samples you collect in a day. We're making sure there is documentation of when the field work was conducted, by whom and, in the case of mid-season staking, we need to know which samples belong to the first survey program and which samples were collected during phase II of the survey program. The date is of particular importance for some biogeochemical surveys when the time of year can influence the geochemical ratios (e.g. twig surveys).
Location, Location, Location
While location is important in real estate, it is also crucial in geochemical surveys. Without knowing where the sample was taken, relationships with the mapped geology cannot be formed and the sample cannot be duplicated. There are three key components to documenting location: projection (e.g. NAD 83 Zone 09N or WGS 84), coordinates and accuracy. Projection is usually only checked at the start of your day and coordinates are documented for each sample. Accuracy assists in determining whether the sample is within a couple metres of the documented coordinates or within 10 metres which can occur at locations with poor southern exposure (in the northern hemisphere) or when within heavily treed areas. Ideally, the sample location should be recorded in your sample book, in your notes and in the GPS. In three places?! Yes, location, location, location is that important.
Sample Type
There are numerous examples of companies that have tried to chase down that elusive, high-grade sample only to discover all the money and resources were spent on float (glacial debris of unknown origin). Rock grab samples should have their source described as float, outcrop, subcrop, talus or felsenmeer (freeze-thaw broken rock). In addition silt, soil, talus fine, chip, channel and core samples should also have their sample type documented. Biogeochemical samples require more detail for their sample type descriptions and should include: plant species, material sampled (twig, needle, leaf or bark) and whether the plant was alive or dead at the time of sampling.
Description
A rock's name will change as more information is collected over the years and as geologists come and go. There are characteristics of your sample which will never change: weathered colour, fresh colour; dimensions; magnetic intensity; carbonate presence; structures descriptions; veining descriptions; alteration-type and intensity; clast/phenocrytst size, morphology, lithology, orientation, and haloes; mineralization and abundance; as well as proposed rock type.
Keeping these four essential elements in mind while prospecting will vastly improve the quality of your data and will ensure your data is referred to for years to come. Happy surveying!
About the Author:
Diana has over 20 years of experience working in the mineral exploration industry searching for diamonds and metals in a range of roles: from heavy minerals lab technician to till sampler, rig geologist, project manager and business owner. Following a Master of Science degree in diamond indicator mineral geochemistry, Diana has conducted field work in BC, NWT, YT, ON (Canada) and in Greenland. She has also been involved, remotely through a BC-based office, on mineral exploration projects located in South America, Africa, Eurasia, and the Middle East. Diana finished a Ph.D. at UNBC in 2017 researching geochemical multivariate statistical analysis and interpretation. Currently, Diana is the owner of Takom Exploration Ltd., a small geological and environmental consulting firm focused on metal exploration in BC and the Yukon.