the Restless Deep: Critical Minerals, Deep Brines, and Geologic Systems That Concentrate Them

Critical minerals are not simply found. They are concentrated by geologic systems-and enrichment alone does not establish a resource. The Restless Deep follows the processes that mobilize, transport, focus, deposit, segregate, and preserve useful materials in the subsurface. Preston Tucker, DBA examines metal-bearing fluids, deep brines, magmatic differentiation, faults and fractures, hydrothermal redistribution, layered intrusions, rare-earth systems, lithium-bearing brines, and the role of time in creating-or destroying-concentrations. The book separates element occurrence from deposit, anomaly from orebody, mineralization from mineral resource, and in-place mass from recoverable material. It also addresses geophysical and geochemical targeting, sampling and assay quality, drilling, extraction, direct lithium extraction, metallurgy, formal resource and reserve boundaries, and the modifying factors that enter once geology alone is no longer enough. Case files include the Smackover, Salton Sea geothermal brines, layered intrusions, and magmatic-hydrothermal systems. The governing rule is simple: ENRICHMENT RESOURCE. The objective is not to promote a commodity, but to show what evidence is required before a deep-Earth concentration can support a defensible resource claim.