GSA HISTORY AND PHILOSOPHY OF GEOLOGY DIVISION STUDENT AWARDS, FIRST PLACE: THE “SCEPTICAL CHYMIST” AS GEOLOGIST? ROBERT BOYLE ON MINERAL FORMATION

I examine Boyle’s thesis that mineral formation is the result of coagulated fluids. Nicolas Steno (1638-1686) is frequently lauded as the father of both modern paleontology and geochronology for his claim that fossils result not from some seminal power in the Earth, but from once living tissue turned to stone. The unique conditions in which fossils are formed led Steno to develop his famed Law of Superposition, or the idea that all rocks and minerals were originally fluid and formed in layers with the oldest on the bottom and youngest on the top. Or so the story goes.

But as Steno explains in his Prodromus (1669), his own thoughts on the matter were actually inspired by English chemist (or chymist) Robert Boyle (1627- 1691). Boyle argued that minerals form from fluids and held that view throughout his career. Recent scholarship, such as Toshihiro Yamada’s, looks at how the transmission of this idea from Boyle to Steno could occur. Yet, to date there has been little consideration as to just how Boyle determined that minerals develop from fluids. Boyle’s idea is nonetheless foundational to the study of minerals, rock formation, and geology.

Understanding Boyle’s views on mineral formation requires further inspection into what he calls a “Petrifick Spirit.” Though his language is reminiscent of archaic notions of seeds with formative powers, his account is actually an analogical description of how fluids interact when minerals form. Boyle’s Petrifick Spirit is not an actual agent, but is the result of heterogeneous fluids. Boyle discusses mineral formation in both Generation of Minerals (1662) and Origin and Virtues of Gems (1672). In each of these treatises, mineral formation is held to occur by the expulsion or disabling of corpuscles within fluids. Though Generation of Minerals was never published, ideas expressed within it significantly influenced Steno’s own thoughts about how minerals and fossil materials develop.

Boyle refined his account of mineral formation over the next decade. Origin and Virtues of Gems appeals to experiments with gems, citing their transparency, the internal texture of gems that resembles the fluids from some of Boyle’s previous chymical experiments, gem colors, and mineral inclusions found within gems. Boyle reasons that gems could not be made as such unless they had once been fluid and con-coagulated.