Scientists detail origins and diversity of every known mineral on Earth
Scientists have detailed the origins and diversity of every known mineral on Earth.
The landmark body of work will help reconstruct the history of life on Earth and guide the search for new minerals and deposits, researchers say.
The catalogue could also help predict possible characteristics of future life, and aid the search for habitable planets and extra-terrestrial life.
Dr Robert Hazen, staff scientist with the Earth and Planets Laboratory, Carnegie Institution for Science, America, said: “This work fundamentally changes our view of the diversity of minerals on the planet.”
Over the 15-year-study, researchers found that nature has used 57 “recipes” to create the more than 10,500 “mineral kinds” through crushing, zapping, boiling, baking and more.
The study sets out that water helped more than 80% of mineral species to form.
While biology – for example, shells, bone and microbes – had a direct or indirect role in the formation of around 50% of the planet’s minerals.
Pyrite, also known as Fool’s Gold, formed in 21 ways – the most of any mineral.
Diamonds formed in nine ways – from outer space to deep Earth.
In twin papers scientists Robert Hazen and Shaunna Morrison from the Carnegie Institution for Science detail a novel approach to clustering (lumping) kindred species of minerals together or splitting off new species based on when and how they originated.
Once how they came about is factored in, the number of “mineral kinds” – a new term – totals more than 10,500.
This is about 75% greater than the roughly 6,000 mineral species recognised by the International Mineralogical Association (IMA) on the basis of crystal structure and chemical composition alone.
Dr Hazen said: “For example, more than 80% of Earth’s minerals were mediated by water, which is, therefore, fundamentally important to mineral diversity on this planet.
“By extension, this explains one of the key reasons why the Moon and Mercury and even Mars have far fewer mineral species than Earth.
“The work also tells us something very profound about the role of biology.
“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, such as by creating an oxygen-rich atmosphere that led to 2,000 minerals that wouldn’t have formed otherwise.”
He added: “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 the paper, nature created 40% of Earth’s mineral species in more than one way – for example, both without the help of living organisms, and with the helping hand of cells.
Of the 5,659 recognized mineral species surveyed by researchers, nine came into being via 15 or more different physical, chemical and/or biological processes.
This includes everything from near-instantaneous formation by lightning or meteor strikes, to changes caused by water-rock interactions or transformations at high pressures and temperature spanning hundreds of millions of years.
To reach their conclusions, Hazen and Morrison built a database of every known process of formation of every known mineral.
Other findings include that some 296 known minerals are thought to pre-date Earth itself, of which 97 are known only from meteorites.
The oldest known minerals are tiny, durable zircon crystals, almost 4.4 billion years old, the researchers found, while 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.
The authors propose that, complementary to the IMA-approved mineral list, new categorisations and groupings be created on the basis of a mineral’s origin.
Professor Luca Bindi, director, department of earth sciences, University of Florence, Italy, said: “Linking the concepts of minerals and evolution may seem counterintuitive but Hazen and Morrison have demonstrated once again that they are highly connected.
“Their two new papers demonstrate in a very elegant way the strong evidence that minerals are the most durable, information-rich objects we can study to understand the origin and evolution of planets.
“To paraphrase a famous Stephen Hawking quote: ‘Hazen and Morrison have become the bearers of the torch of discovery in our quest for knowledge of the mineral kingdom’.”
The research, sponsored in part by Nasa, is published in the American Mineralogist journal.