A new way of categorizing minerals

All diamonds have no common history. Some diamonds were formed in space while some diamonds were formed in the earth’s mantle. Five thousand years ago, a large meteorite that struck a carbon-rich sediment on Earth produced a striking diamond.

All diamonds have different compositions and origins, but all are classified as “diamond” by the definitive guide to minerals.

For many physicists, this inconsistency is not a problem. However, there are some unanswered questions for planetary researchers, geobiologists, paleontologists, and others striving to understand the historical context of minerals.

Working with Carol Cleland, Professor of Philosophy of Science at Boulder CU, Robert Hazen and Shaunna Morrison of Carnegie have addressed this shortcoming with a new “evolutionary system” of mineral classification that includes historical data and changes in the diversity and distribution of minerals by more than reflects 4 billion years of geological history.

Hazen said: “We came together from very different fields of philosophy and planetary research to see if there was a rigorous way of including the dimension of time in discussions of the solid materials that make up the earth.”

“The IMA classification system for minerals dates back to the 19th century when geologist James Dwight Dana outlined a way to categorize minerals based on unique combinations of idealized compositions of major elements and geometrically idealized crystal structure.”

Morrison said, “For example, the IMA defines quartz as pure silicon dioxide, but the existence of this idealized version is entirely fictional. Every piece of quartz contains imperfections – traces of its creation process that make it unique. “

“This approach to the categorization system means that minerals with significantly different historical origins – as in the example of diamonds – are grouped together, while other minerals that have a common causal history are separated.”

Cleland said: “Differences in the history of a diamond or quartz crystal are critical because the conditions under which a sample was formed and the modifications it underwent” are far more informative than the mere fact that a crystal qualifies as diamond or quartz is. “

A new system is needed to categorize minerals that contain historical “natural species”.

The solution proposed by Hazen, Morrison, and Cleland of calling a “bootstrap” approach based on historically insightful, information-rich chemical, physical, and biological properties of solid materials. This strategy enables scientists to build a historical system of mineral species while ignoring the underlying theoretical principles.

Hazen said: “Minerals are the most durable and information-rich objects we can study to understand the origins and evolution of our planet. Our new evolutionary approach to the classification of minerals complements the existing protocols and offers the possibility of precisely documenting the earth’s history. “

Journal reference:
  1. Carol E. Cleland et al., “Historic Natural Species and Mineralogy: Systematizing Contingency in the Context of Necessity,” PNAS (2020). DOI: 10.1073 / pnas.2015370118