Earth's geology on life is easy to see, with organisms adapting to environments as different as deserts, mountains, forests, and oceans. The full impact of life on geology, however, can be easy to miss.
A comprehensive new survey of our planet's minerals now corrects that omission. Among its findings is evidence that about half of all mineral diversity is the direct or indirect result of living things and their byproducts. It's a discovery that could provide valuable insights to scientists piecing together Earth's complex geological history—and also to those searching for evidence of life beyond this world.
[...] Their new taxonomy, based on an algorithmic analysis of thousands of scientific papers, recognizes more than 10,500 different types of minerals. That's almost twice as many as the roughly 5,800 mineral "species" in the classic taxonomy of the International Mineralogical Association, which focuses strictly on a mineral's crystalline structure and chemical makeup.
[...] Take, for example, pyrite crystals (commonly known as fool's gold). "Pyrite forms in 21 fundamentally different ways," Hazen said. Some pyrite crystals form when chloride-rich iron deposits heat up deep underground over millions of years. Others form in cold ocean sediments as a byproduct of bacteria that break down organic matter on the seafloor. Still others are associated with volcanic activity, groundwater seepage, or coal mines.
"Each one of those kinds of pyrite is telling us something different about our planet, its origin, about life, and how it's changed through time," said Hazen.
For that reason, the new papers classify minerals by "kind," a term that Hazen and Morrison define as a combination of the mineral species with its mechanism of origin (think volcanic pyrite versus microbial pyrite). Using machine learning analysis, they scoured data from thousands of scientific papers and identified 10,556 distinct mineral kinds.
Morrison and Hazen also identified 57 processes that individually or in combination created all known minerals. These processes included various types of weathering, chemical precipitations, metamorphic transformation inside the mantle, lightning strikes, radiation, oxidation, massive impacts during Earth's formation, and even condensations in interstellar space before the planet formed. They confirmed that the biggest single factor in mineral diversity on Earth is water, which through a variety of chemical and physical processes helps to generate more than 80 percent of minerals.
[...] How deeply the mineralogical is interwoven with the biological might not come as a huge surprise to earth scientists, Sahai said, but Morrison and Hazen's new taxonomy "put a nice systematization on it and made it more accessible to a broader community."
[...] Still, Hazen and Morrison hope that their taxonomy might one day be used to decode the geologic history of other planets or moons and to search for hints of life there, past or present. When examining a Martian crystal, for example, researchers could use the new mineralogical framework to look at features like grain size and structure defects to determine whether it could have been produced by an ancient microbe rather than by a dying sea or a meteor strike.
Journal References:
• Robert M. Hazen, Shaunna M. Morrison, Sergey V. Krivovichev, et al. Lumping and splitting: Toward a classification of mineral natural kinds, American Mineralogist (DOI: 10.2138/am-2022-8105)
• Robert M. Hazen, Shaunna M. Morrison. On the paragenetic modes of minerals: A mineral evolution perspective, American Mineralogist (DOI: 10.2138/am-2022-8099)
(Score: 1, Funny) by Anonymous Coward on Thursday July 28 2022, @11:14PM
This mineral keeps appearing in dirty socks and t-shirts. Any ideas?
(Score: 2, Interesting) by shrewdsheep on Friday July 29 2022, @09:59AM (1 child)
TLDR; What is the combined mass of these biogenic minerals? While they seem to be diverse, my guess is that overall mass should be in the ppb range.
(Score: 4, Interesting) by PiMuNu on Friday July 29 2022, @11:43AM
> ppb range.
Without thinking too hard, limestone and chalk make up a significant proportion of the UK's surface, both significantly biological in origin. I guess 10 % or more. Clays also probably contain quite some organic matter.