Pure Michigan copper contains unexpected mercury

November 24, 2025Theory

Source: Ep. 6 - The Shaman and the Philosopher - Rick Osmon by Institute for Natural Philosophy

Site mentioned

📍 Lake Superior

A wall of pure native copper 40-80 ft tall runs through Lake Superior's Midcontinent Rift (1.1 billion years old). The copper assays at 99.9% purity with traces of mercury - accessible from surface around 6000 BC, with mining evidence dating to around 4500 BC. The Keweenaw Peninsula hosted massive native copper deposits, with millions of pounds extracted by ancient peoples before European contact. 🏔️🪙

Key facts

The Superior Rift formed 3 billion years ago
A wall of nearly pure copper exists in Lake Superior (40-80 feet tall, 18 ft thick)
Between 100 million pounds and 120 million tons of copper were extracted
The copper assays at 99.9% purity - normally requires electrolysis
Mercury is present in the raw nuggets, surprising testing facilities in Sweden
Mercury escapes when copper is heated above 500 degrees Celsius
This copper was accessible from the surface around 4000 BC
Mining likely began around 2500 BC
Glaciers moved copper pieces as far south as the size of a trailer