Survey Track: Geology, Geophysics, Mapping and Core · Module 1 of 4 · about 15 min
Rocks, deposits and critical minerals
An ore deposit is rock with enough valuable mineral to mine at a profit. Geologists group deposits by how they formed. Porphyry deposits form around cooling magma and supply much of the world's copper. Magmatic sulfide deposits hold nickel, copper and platinum-group metals. Pegmatites can host lithium in minerals like spodumene. Some lithium also sits in underground brines.
The U.S. Geological Survey keeps a list of critical minerals, the ones that matter to the economy and security and have supply risks. USGS also publishes Mineral Commodity Summaries every year with production, reserves and import data for dozens of commodities. That is the place to check numbers instead of trusting headlines.
Field geology is still the base of exploration. You walk outcrops, map rock types and structures, take samples and record exactly where each came from. A sample with a bad location is worthless.
Exploration is mostly finding nothing. Most prospects never become mines. The job is to rule areas out cheaply and fast, so money goes to the few that deserve drilling.
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Module quiz
5 questions, 4 correct to pass. You'll see what you missed and why, and you can retake it.