Isaac Newton developed an unusual and little-known theory of subterranean metal and mineral formation by integrating concepts drawn from his own alchemical experimentation and reading with the mechanical philosophy that he inherited from other seventeenth-century figures such as René Descartes and Robert Boyle. Until recently, Newton’s geochemical theory has been known incompletely, since the primary text in which it is found, Smithsonian MS Dibner 1031B, had only been published in a fragmentary form. Thanks to the 2006 edition of the complete manuscript appearing on the online Chymistry of Isaac Newton site (www.chymistry.org), it is now possible to arrive at a far more complete understanding of Newton’s early theory of metallogenesis than before. The present paper provides a concise analysis of Newton’s views on this subject, showing how he integrated themes from alchemy and the better-known parts of his natural philosophy to arrive at a novel theory of the production of metals and minerals within the earth.