Earth May Have 1,500 Undiscovered Minerals

Minerals are formed when geological or biological activity create unique combinations of elements. The type of mineral you get is dependent on the environment in which it forms.  For geological minerals, pressure and temperature can vary to give different combinations that are difficult to replicate in a lab.  For biological minerals, life slowly but surely undergoes processes that shift and shape minerals, usually as a waste product from obtaining energy. But with 3 billion years of life forming and reforming on our planet, springing up new diversity and losing countless species to extinction, there may be minerals that we simply haven’t heard of, residing deep underground waiting to be discovered. But which process gives rise to more minerals? Biological or Geological?

A rhodochrosite specimen from Butte, Mont. Credit: Robert Downs

About ten years ago, Robert Hazen from the Carnegie Institution showed that the two-thirds of the diversity seen in Earth’s minerals primarily arose as a byproduct of life, and specifically around 2.4 Billion years ago with the rise of photosynthesis in plants. This gave the planet an atmosphere rich in oxygen.

Now, taking it one step further, Hazen and colleagues are using statistical models of ecosystem research and analysis of mineralogical databases to study the potential of our ecosystem to produce minerals, and the results are fascinating.

They calculated that there is a 22 percent chance that a particular mineral is found in only one place on Earth, while 65 percent are found in 10 or less places, called localities.  This means that most minerals should be rare.

“Minerals follow the same kind of frequency of distribution as words in a book,” Hazen explained. “For example, the most-used words in a book are extremely common such as ‘and,’ ‘the,’ and ‘a.’ Rare words define the diversity of a book’s vocabulary. The same is true for minerals on Earth. Rare minerals define our planet’s mineralogical diversity.”

The research suggests that as many as 1,500 minerals are somewhere on the planet waiting to be found, or once existed somewhere on Earth in the past.   However, there are patterns to the missing minerals.  Colour is a big one, since white minerals may be tougher to distinguish from other rocks.  Hazen has predicted that about 35% of Sodium minerals haven’t been discovered due to poor crystallization, solubility in water, and white colour.

The Earth’s mineral composition also acts like a fingerprint, with the specific history of the planet leading to what we see. “This means that despite the physical, chemical, and biological factors that control most of our planet’s mineral diversity, Earth’s mineralogy is unique in the cosmos,” Hazen said.

 

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