#45 Seamount Crusts with Thomas Kuhn

In this episode, Thomas Kuhn (Marine Geologist and Project Manager, Federal Institute for Geosciences and Natural Resources – BGR, Germany) breaks down how ferromanganese crusts form on the ocean floor, and why the scientific community has been looking at the wrong part of the mountain for decades.

This conversation gets deep into the chemistry of cobalt enrichment, the role of tidal currents in exposing crust-bearing rock on seamount summits, and why a single underwater plateau could supply Germany’s entire rare earth element demand for eight years — a finding that is genuinely new to the field.

Thomas brings a perspective that is rare in the deep-sea mining conversation: three decades of hands-on geological fieldwork combined with the institutional weight of managing Germany’s own exploration licenses. He offers a grounded, evidence-based case for why ferromanganese crusts deserve far more attention than they currently get — and what responsible development of those resources might actually look like.

Follow Thomas on LinkedIn: https://www.linkedin.com/in/thomas-kuhn-a02204288/

Chapters:

* 00:00:00 – Teaser: One Seamount, Eight Years of Rare Earths

* 00:00:18 – Introducing Thomas Kuhn & BGR

* 00:01:42 – Thomas’s Path to Marine Geology

* 00:06:41 – How Has Public Perception of Deep-Sea Mining Changed?

* 00:12:52 – Natural Variability & The Right Timescale

* 00:24:47 – Crust Formation 101: How Ferromanganese Crusts Form

* 00:29:47 – Why Cobalt Gets Trapped (And Nickel Doesn’t)

* 00:40:05 – Water Depth, Growth Rates & Crust Composition

* 00:44:32 – The Seamount Summit Discovery

* 00:51:23 – Tidal Currents: The Missing Piece

* 00:55:08 – Biology, Connectivity & Environmental Recovery

* 00:58:24 – How Far Are We From Mining Crusts?

* 00:59:38 – Heavy Rare Earths: The Hidden Value

* 01:05:09 – Thomas’s Closing Message & Wrap-Up

Resources Mentioned:

* Hein, Koschinsky & Kuhn (2020) — nodule composition: https://www.nature.com/articles/s43017-020-0027-0

* Cruise report SO313 — Louisville Seamounts: https://doi.org/10.48433/cr_so313

* BGR marine minerals page: https://www.bgr.bund.de/EN/Themen/Rohstoffe/Marine-mineralische/marine-mineralische_node.html

* An example of the combination of the occurrence of ferromanganese crusts on top of seamounts in relation to water column currents: https:/ / doi.org/ 10.1016/ j.oregeorev.2019.103131

* An example of the occurrence of ferromanganese crusts on a NW Pacific seamount: http://dx.doi.org/10.1016/j.oregeorev.2016.09.032

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