Geology

Nature Used 57 Recipes To Create Earth’s 10,500+ “Mineral Kinds”

By ScientifiCult 1 July 2022

Crushed, Zapped, Boiled, Baked And More: Nature Used 57 Recipes To Create Earth’s 10,500+ “Mineral Kinds”

Washington, DC—A 15-year study led by Carnegie’s Robert Hazen and Shaunna Morrison 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 our planet, guide the search for new minerals and ore deposits, predict possible characteristics of future life, and aid the search for habitable exoplanets and extraterrestrial life.

For more than a century, thousands of mineralogists from around the globe have carefully documented “mineral species” based on their unique combinations of chemical composition and crystal structure. Carnegie scientists Robert Hazen and Shaunna Morrison took a different approach, emphasizing how and when each kind of mineral appeared through more than 4.5 billion years of Earth history.

In twin papers published by American Mineralogist, Hazen, Morrison, and their collaborators detail how they used extensive database analysis to cluster kindred species of minerals together and distinguish new mineral species based on when and how they originated, rather than solely on their chemical and physical characteristics.

Their work indicates that the number of “mineral kinds”—a term coined in 2020 by Hazen and Morrison—totals more than 10,500. In comparison, the International Mineralogical Association recognizes about 6,000 mineral species on the basis of crystal structure and chemical composition alone.

pyrite 21 mineral kinds — Nature Used 57 Recipes To Create Earth’s 10,500+ “Mineral Kinds”: Pyrite forms in 21 different ways, the most of any mineral. Pyrite is so stable that it forms both at high temperature and low, both with and without water, and both with the help of microbes and in harsh environments where life plays no role whatsoever. These examples formed by the gradual precipitation of crystals from a solution rich in iron and sulfur. The large cubes are wonders of nature. Credit: ARKENSTONE/Rob Lavinsky

“This work fundamentally changes our view of the diversity of minerals on the planet,” Hazen explained. “For example, more than 80 percent of Earth’s minerals were mediated by water, which is, therefore, fundamentally important to mineral diversity on this planet. By extension, it explains one of the key reasons why the Moon and Mercury and even Mars have far fewer mineral species than Earth.”

“It also tells us something very profound about the role of biology,” he added. “One third of Earth’s minerals could not have formed without biology—shells and bones and teeth, or microbes, for example—or the vital indirect role of biology—importantly by creating an oxygen-rich atmosphere that led to 2,000 minerals that wouldn’t have formed otherwise. Each mineral specimen has a history. Each tells a story. Each is a time capsule that reveals Earth’s past as nothing else can.”

According to Hazen and Morrison—along with collaborators Sergey Krivovichev of the Russian Academy of Sciences and Robert Downs of the University of Arizona—nature created 40 percent of Earth’s mineral species by more than one method—for example, many minerals arose both abiotically and with a helping hand from living organisms—and in several cases more than 15 different “recipes” produced the same crystal structure and chemical composition.

Of the 5,659 mineral species surveyed by Hazen and colleagues, nine arose via 15 or more origin pathways, each incorporating various combinations of physical, chemical, and biological processes—everything from near-instantaneous formation by lightning or meteor strikes, to changes caused by water-rock interactions or high-pressure, high-temperature transformations that took place over hundreds of millions of years.

And, as if to demonstrate a sense of humor, nature has used 21 different ways over the last 4.56 billion years to create pyrite, also known as Fool’s Gold—the most origin stories of any mineral. Pyrite, composed of one part iron to two parts sulfide, is so stable that it forms under a huge variety of circumstances, including meteorites, volcanos, hydrothermal deposits, by pressure between layers of rock, near-surface rock weathering, in microbially-precipitated deposits, and via several mining-associated processes.

To reach their conclusions, Hazen and Morrison built a database of every known process of formation of every known mineral. Relying on large, open-access mineral databases, amplified by thousands of primary research articles on the geology of mineral localities around the world, they identified 10,556 different combinations of minerals and modes of formation.

“No one has undertaken this huge task before,” said Hazen, who honored last year by the IMA with its medal for his outstanding achievements in mineral crystal chemistry, particularly in the field of mineral evolution. “In these twin papers, we are putting forward our best effort to lay the groundwork for a new approach to recognizing different kinds of minerals. We welcome the insights, additions, and future versions of the mineralogical community.”

The papers’ groundbreaking observations and conclusions include:

Water has played a dominant role in the mineral diversity of Earth, was involved in the formation of more than 80 percent of mineral species.
Life played a direct or indirect role in the formation of almost half of known mineral species while a third of known minerals—more than 1,900 species—formed exclusively as a consequence of biological activities.
Rare elements play a disproportionate role in Earth’s mineral diversity. Just 41 elements—together constituting less than 5 parts per million of Earth’s crust—are essential constituents in some 2,400 (more than 42 percent) of Earth’s minerals. The 41 elements include arsenic, cadmium, gold, mercury, silver, titanium, tin, uranium, and tungsten.
Much of Earth’s mineral diversity was established within the planet’s first 250 million years
Some 296 known minerals are thought to pre-date Earth itself, of which 97 are known only from meteorites, with the age of some individual mineral grains estimated at 7 billion years—which was billions of years before the origin of our Solar System.
The oldest known minerals are tiny, durable zircon crystals that are almost 4.4 billion years old.
More than 600 minerals have derived from human activities, including more than 500 minerals caused by mining, 234 of them formed by coal mine fires.

Hazen, Morrison, and their colleagues propose that, complementary to the IMA-approved mineral list, new categorizations and groupings be created on the basis of a mineral’s genesis. For example, science can group 400 minerals formed by condensation at volcanic fumaroles—the openings in the Earth’s surface that emit steam and volcanic gasses.

Their papers detail other considerations in the clustering and classification of minerals, such as the eon in which they formed. For example, Earth’s so-called Great Oxidation Event about 2.3 billion years ago led new minerals to form at the planet’s near-surface. And about 4.45 billion years ago, when water first appeared, the earliest water-rock interactions may have produced as many as 350 minerals in near-surface marine and terrestrial environments.

It appears, too, that hundreds of different minerals may have formed on Earth prior to the giant impact that vaporized much of our planet’s crust and mantle and led to the Moon’s formation about 4.5 billion years ago. If so, those minerals were obliterated, only to reform as Earth cooled and solidified.

Beyond accidental mineral creations, humanity has manufactured countless thousands of mineral-like compounds that don’t qualify as minerals by the IMA standards, but do qualify as mineral kinds by Hazen and Morrison’s methodology. This includes building materials, semiconductors, laser crystals, specialty alloys, synthetic gemstones, plastic debris and the like—all “likely to persist for millions of years in the geologic record, providing a clear sedimentary horizon that marks the so-called “Anthropocene Epoch.”

Meanwhile, there are also 77 “biominerals,” that were formed by a variety of metabolic processes—this includes everything from minerals derived by corals, shells, and stinging nettles to minerals in bones, teeth, and kidney stones. Another 72 minerals originated directly or indirectly from the guano and urine of birds and bats.

The researchers noted that between the formation of oceans, the extensive development of continental crust, and perhaps even the initiation of some early form of the process that now drive plate tectonics, many important mineral-forming processes—and the origins of as many as 3,534 mineral species—took place in Earth’s first 250 million years. If so, then most of the geochemical and mineralogical environments invoked in models of life’s origins would have been present by 4.3 billion years ago.

If life is “a cosmic imperative that emerges on any mineral- and water-rich world,” the authors concluded, “then these findings support the hypothesis that life on Earth emerged rapidly, in concert with a vibrant, diverse Mineral Kingdom, in the earliest stages of planetary evolution.”

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The research was supported by the John Templeton Foundation, the NASA Astrobiology Institute ENIGMA team, and the Carnegie Institution for Science.

Bibliographic information:

On the paragenetic modes of minerals: A mineral evolution perspective, American Mineralogist (1-Jul-2022), DOI: 10.2138/am-2022-8099

Press release from Carnegie Science on the work about “mineral kinds”.

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Astronomy

GJ 1132 b: Hubble sees new atmosphere forming on the rocky exoplanet

By ScientifiCult 13 March 2021

Hubble sees new atmosphere forming on a rocky exoplanet, GJ 1132 b

The planet GJ 1132 b appears to have begun life as a gaseous world with a thick blanket of atmosphere. Starting out at several times the radius of Earth, this so-called “sub-Neptune” quickly lost its primordial hydrogen and helium atmosphere, which was stripped away by the intense radiation from its hot, young star. In a short period of time, it was reduced to a bare core about the size of Earth.

To the surprise of astronomers, new observations from Hubble [1] have uncovered a secondary atmosphere that has replaced the planet’s first atmosphere. It is rich in hydrogen, hydrogen cyanide, methane and ammonia, and also has a hydrocarbon haze. Astronomers theorise that hydrogen from the original atmosphere was absorbed into the planet’s molten magma mantle and is now being slowly released by volcanism to form a new atmosphere. This second atmosphere, which continues to leak away into space, is continually being replenished from the reservoir of hydrogen in the mantle’s magma.

“This second atmosphere comes from the surface and interior of the planet, and so it is a window onto the geology of another world,” explained team member Paul Rimmer of the University of Cambridge, UK. “A lot more work needs to be done to properly look through it, but the discovery of this window is of great importance.”

Pictured here is the region around the host star of the exoplanet GJ 1132 b. Credit:
ESA/Hubble, Digitized Sky Survey 2, CC BY 4.0.
Acknowledgement: Davide De Martin

“We first thought that these highly radiated planets would be pretty boring because we believed that they lost their atmospheres,” said team member Raissa Estrela of the Jet Propulsion Laboratory at the California Institute of Technology in Pasadena, California, USA. But we looked at existing observations of this planet with Hubble and realised that there is an atmosphere there.”

“How many terrestrial planets don’t begin as terrestrials? Some may start as sub-Neptunes, and they become terrestrials through a mechanism whereby light evaporates the primordial atmosphere. This process works early in a planet’s life, when the star is hotter,” said team leader Mark Swain of the Jet Propulsion Laboratory. “Then the star cools down and the planet’s just sitting there. So you’ve got this mechanism that can cook off the atmosphere in the first 100 million years, and then things settle down. And if you can regenerate the atmosphere, maybe you can keep it.”

In some ways, GJ 1132 b has various parallels to Earth, but in some ways it is also very different. Both have similar densities, similar sizes, and similar ages, being about 4.5 billion years old. Both started with a hydrogen-dominated atmosphere, and both were hot before they cooled down. The team’s work even suggests that GJ 1132 b and Earth have similar atmospheric pressure at the surface.

This plot shows the spectrum of the atmosphere of an Earth sized rocky exoplanet, GJ 1132 b, which is overlaid on an artist’s impression of the planet. The orange line represents the model spectrum. In comparison, the observed spectrum is shown as blue dots representing averaged data points, along with their error bars. This analysis is consistent with GJ 1132 b being predominantly a hydrogen atmosphere with a mix of methane and hydrogen cyanide. The planet also has aerosols which cause scattering of light. This is the first time a so-called “secondary atmosphere,” which was replenished after the planet lost its primordial atmosphere, has been detected on a world outside of our solar system. Credit:
NASA, ESA, and P. Jeffries (STScI)

However, the planets’ formation histories are profoundly different. Earth is not believed to be the surviving core of a sub-Neptune. And Earth orbits at a comfortable distance from our yellow dwarf Sun. GJ 1132 b is so close to its host red dwarf star that it completes an orbit the star once every day and a half. This extremely close proximity keeps GJ 1132 b tidally locked, showing the same face to its star at all times — just as our moon keeps one hemisphere permanently facing Earth.

“The question is, what is keeping the mantle hot enough to remain liquid and power volcanism?” asked Swain. “This system is special because it has the opportunity for quite a lot of tidal heating.”

The phenomenon of tidal heating occurs through friction, when energy from a planet’s orbit and rotation is dispersed as heat inside the planet. GJ 1132 b is in an elliptical orbit, and the tidal forces acting on it are strongest when it is closest to or farthest from its host star. At least one other planet in the host star’s system also exerts a gravitational pull on the planet. The consequences are that the planet is squeezed or stretched by this gravitational “pumping.” That tidal heating keeps the mantle liquid for a long time. A nearby example in our own Solar System is the Jovian moon, Io, which has continuous volcanism as a result of a tidal tug-of-war between Jupiter and the neighbouring Jovian moons.

The team believes the crust of GJ 1132 b is extremely thin, perhaps only hundreds of feet thick. That’s much too feeble to support anything resembling volcanic mountains. Its flat terrain may also be cracked like an eggshell by tidal flexing. Hydrogen and other gases could be released through such cracks.

“This atmosphere, if it’s thin — meaning if it has a surface pressure similar to Earth — probably means you can see right down to the ground at infrared wavelengths. That means that if astronomers use the James Webb Space Telescope to observe this planet, there’s a possibility that they will see not the spectrum of the atmosphere, but rather the spectrum of the surface,” explained Swain. “And if there are magma pools or volcanism going on, those areas will be hotter. That will generate more emission, and so they’ll potentially be looking at the actual geological activity — which is exciting!”

This result is significant because it gives exoplanet scientists a way to figure out something about a planet’s geology from its atmosphere,” added Rimmer. “It is also important for understanding where the rocky planets in our own Solar System — Mercury, Venus, Earth and Mars, fit into the bigger picture of comparative planetology, in terms of the availability of hydrogen versus oxygen in the atmosphere.”

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Notes:

[1] The observations were conducted as part of the Hubble observing program #14758 (PI: Zach Berta-Thomson).

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Astronomy

Radar points to moon being more metallic than researchers thought

By ScientifiCult 4 July 2020

What started out as a hunt for ice lurking in polar lunar craters turned into an unexpected finding that could help clear some muddy history about the Moon’s formation.

Team members of the Miniature Radio Frequency (Mini-RF) instrument on NASA’s Lunar Reconnaissance Orbiter (LRO) spacecraft found new evidence that the Moon’s subsurface might be richer in metals, like iron and titanium, than researchers thought. That finding, published July 1 in Earth and Planetary Science Letters, could aid in drawing a clearer connection between Earth and the Moon.

“The LRO mission and its radar instrument continue to surprise us with new insights about the origins and complexity of our nearest neighbor,” said Wes Patterson, Mini-RF principal investigator from the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, and a study coauthor.

Moon metallic — This image based on data from NASA’s Lunar Reconnaissance Orbiter spacecraft shows the face of the Moon we see from Earth. The more we learn about our nearest neighbor, the more we begin to understand the Moon as a dynamic place with useful resources that could one day even support human presence. Credits: NASA / GSFC / Arizona State University

Substantial evidence points to the Moon as the product of a collision between a Mars-sized protoplanet and young Earth, forming from the gravitational collapse of the remaining cloud of debris. Consequently, the Moon’s bulk chemical composition closely resembles that of Earth.

Look in detail at the Moon’s chemical composition, however, and that story turns murky. For example, in the bright plains of the Moon’s surface, called the lunar highlands, rocks contain smaller amounts of metal-bearing minerals relative to Earth. That finding might be explained if Earth had fully differentiated into a core, mantle and crust before the impact, leaving the Moon largely metal-poor. But turn to the Moon’s maria — the large, darker plains — and the metal abundance becomes richer than that of many rocks on Earth.

This discrepancy has puzzled scientists, leading to numerous questions and hypotheses regarding how much the impacting protoplanet may have contributed to the differences. The Mini-RF team found a curious pattern that could lead to an answer.

Using Mini-RF, the researchers sought to measure an electrical property within lunar soil piled on crater floors in the Moon’s northern hemisphere. This electrical property is known as the dielectric constant, a number that compares the relative abilities of a material and the vacuum of space to transmit electric fields, and could help locate ice lurking in the crater shadows. The team, however, noticed this property increasing with crater size.

For craters approximately 1 to 3 miles (2 to 5 kilometers) wide, the dielectric constant of the material steadily increased as the craters grew larger, but for craters 3 to 12 miles (5 to 20 kilometers) wide, the property remained constant.

“It was a surprising relationship that we had no reason to believe would exist,” said Essam Heggy, coinvestigator of the Mini-RF experiments from the University of Southern California in Los Angeles and lead author of the published paper.

Discovery of this pattern opened a door to a new possibility. Because meteors that form larger craters also dig deeper into the Moon’s subsurface, the team reasoned that the increasing dielectric constant of the dust in larger craters could be the result of meteors excavating iron and titanium oxides that lie below the surface. Dielectric properties are directly linked to the concentration of these metal minerals.

If their hypothesis were true, it would mean only the first few hundred meters of the Moon’s surface is scant in iron and titanium oxides, but below the surface, there’s a steady increase to a rich and unexpected bonanza.

Comparing crater floor radar images from Mini-RF with metal oxide maps from the LRO Wide-Angle Camera, Japan’s Kaguya mission and NASA’s Lunar Prospector spacecraft, the team found exactly what it had suspected. The larger craters, with their increased dielectric material, were also richer in metals, suggesting that more iron and titanium oxides had been excavated from the depths of 0.3 to 1 mile (0.5 to 2 kilometers) than from the upper 0.1 to 0.3 miles (0.2 to 0.5 kilometers) of the lunar subsurface.

“This exciting result from Mini-RF shows that even after 11 years in operation at the Moon, we are still making new discoveries about the ancient history of our nearest neighbor,” said Noah Petro, the LRO project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The MINI-RF data is incredibly valuable for telling us about the properties of the lunar surface, but we use that data to infer what was happening over 4.5 billion years ago!”

These results follow recent evidence from NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission that suggests a significant mass of dense material exists just a few tens to hundreds of kilometers beneath the Moon’s enormous South Pole-Aitken basin, indicating that dense materials aren’t uniformly distributed in the Moon’s subsurface.

The team emphasizes that the new study can’t directly answer the outstanding questions about the Moon’s formation, but it does reduce the uncertainty in the distribution of iron and titanium oxides in the lunar subsurface and provide critical evidence needed to better understand the Moon’s formation and its connection to Earth.

“It really raises the question of what this means for our previous formation hypotheses,” Heggy said.

Anxious to uncover more, the researchers have already started examining crater floors in the Moon’s southern hemisphere to see if the same trends exist there.

LRO is managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland for the Science Mission Directorate at NASA Headquarters in Washington. Mini-RF was designed, built and tested by a team led by APL, Naval Air Warfare Center, Sandia National Laboratories, Raytheon and Northrop Grumman.

For more information on LRO, visit:

https://www.nasa.gov/lro

Press release from NASA/Space Goddard Flight Center, by Jeremy Rehm

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