A 15-year study by the Carnegie Institution for Science details the origins and diversity of every known mineral on Earth, a landmark body of work that will help reconstruct the history of life on earth, guide the search for new minerals and ore deposits, predict possible features of future life, and facilitate the search for habitable planets and extraterrestrial life.
In twin papers published by American Mineralogist and sponsored in part by NASA, Carnegie scientists Robert Hazen and Shaunna Morrison detail a novel approach to clustering (clustering) related species of minerals or separating new species based on timing. and how they originated.
Once mineral genesis is taken into account, the number of “mineral types” – a newly coined term – totals over 10,500, a number about 75% greater than the approximately 6,000 mineral species recognized by the International Mineralogical Association. (IMA) based on crystal structure and chemical composition alone.
“This work fundamentally changes our view of mineral diversity on the planet,” says Hazen, a scientist at the Earth and Planets Laboratory, Carnegie Institution for Science, Washington DC.
“For example, more than 80% of the Earth’s minerals are carried by water, which is therefore of fundamental importance for the mineral diversity of this planet. By extension, this explains one of the main reasons why the moon and mercury and even mars have far fewer mineral species than the earth.
“The work also tells us something very profound about the role of biology,” he adds. “A third of the earth’s minerals could not have formed without biology – shells, bones and teeth, or microbes, for example, or the vital indirect role of biology, for example in creating an atmosphere rich in oxygen which led to 2,000 minerals that would ‘I didn’t form otherwise.
“Each mineral specimen has a story. Each tells a story. Each is a time capsule that reveals Earth’s past like nothing else can.
According to the article, nature created 40% of Earth’s mineral species in more than one way – for example, both abiotically and with the help of cells – and in several cases used more of 15 different recipes to produce the same crystal structure and chemical composition.
Of the 5,659 recognized mineral species studied by Hazen and his colleagues, nine arose through at least 15 different physical, chemical and/or biological processes – ranging from near-instantaneous formation by lightning or meteor impacts to changes caused by water-rock interactions. or transformations at high pressures and temperatures spanning hundreds of millions of years.
And, as if to show she has a sense of humor, nature has used 21 different ways over the past 4.5 billion years to create pyrite (aka Fool’s Gold) – the world champion mineral. of various origins.
Pyrite forms at high and low temperatures, with and without water, with the help of microbes and in harsh environments where life plays no role.
Composed of one part iron to two parts sulfide (FeS2), pyrite is derived and delivered via meteorites, volcanoes, hydrothermal deposits, pressure between layers of rock, weathering of rocks near the surface, deposits precipitated by microbes, several processes associated with mining, including coal mine fires, and many other means.
To arrive at their conclusions, Hazen and Morrison built a database of every known process of formation of every known mineral.
Drawing on extensive open-access mineral databases, amplified by thousands of primary research papers on the geology of mineral localities around the world, they identified 10,556 different combinations of minerals and modes of formation, detailed in the article “On the paragenetic modes of minerals: a perspective of mineral evolution. »