Fine Fractions & Big Discoveries: A Deep Dive into Drainage Geochem with Mary Doherty

About this episode

This episode features a discussion on stream sediment sampling and its developments in exploration geochemistry with guest Mary Doherty.

This month on GeOCHemISTea, we are talking about one of exploration geochemistry’s most foundational, and rapidly evolving, methods: stream sediment sampling. Sam is joined by geochemical consultant and educator Mary Doherty, lead author of a 2023 review on stream sediment geochemistry, published in Geochemistry: Exploration, Environment, Analysis . Mary shares a career’s worth of field, lab, and leadership experience, from carrying samples for her USGS geologist father as a child to building geochem training programs for Newmont and ALS, and recently teaching at the Colorado School of Mines. We talk about key developments in stream sediment methods, from fine fraction and BLEG to HMC and indicator mineral chemistry, as well as how to choose the right tool for the job. The episode also covers the practicalities of QA/QC, field planning, and how geomorphology and hydrology shape interpretation. Mary emphasizes the importance of training, knowledge-sharing, and the growing integration of mineralogical data, and machine learning into modern workflows. Whether you are designing your first drainage survey or revisiting legacy data, this episode is a reminder that good geochemistry…

People in this episode

Host: Sam Scher

Guest: Mary Doherty

Topics covered

• stream sediment sampling
• exploration geochemistry
• geochemical methods
• QA/QC
• geomorphology
• hydrology
• machine learning

Keywords

• stream sediment
• geochemistry
• field planning
• mineral exploration
• training programs
• machine learning
• QA/QC

Mentioned in this episode

Organizations: USGS, Newmont, ALS, Colorado School of Mines

Books & works: Stream sediment geochemistry in mineral exploration: a review of fine-fraction, clay-fraction, bulk leach gold, heavy mineral concentrate and indicator mineral chemistry

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