Most mineral projects do not fail because of poor technical work. They fail in the space between what is known and what is decided. Technical Judgment in Mineral Projects addresses a critical but largely invisible gap in the mining industry: the translation of technically sound estimation into high-stakes capital decisions. Despite advances in geology, resource modeling, and engineering, projects continue to underperform—delivering lower grades, higher costs, and reduced value compared to pre-production forecasts. This book argues that the problem is not estimation. It is judgment. Written for experienced geologists, mining engineers, metallurgists, and project decision-makers, this work introduces technical judgment as a structured discipline—one that goes beyond models, beyond compliance, and into the realm of decision quality under uncertainty. Through a rigorous framework, the book explores: • Why model quality does not guarantee decision quality • How assumptions silently propagate from drill data to NPV • Where geological, metallurgical, and geotechnical uncertainty truly matters • Why sensitivity analysis often creates false confidence • How cognitive bias shapes technical decisions in high-pressure environments Across real-world composite cases, readers are guided through the hidden failure modes that repeatedly undermine mineral projects—and shown how to identify them before capital is committed. This is not a book about how to build better models. It is a book about how to make defensible decisions when models are not enough. For professionals operating at the intersection of technical rigor and financial consequence, this book provides a new lens—and a necessary discipline—for navigating uncertainty in mineral project development.