When we think about humankind's creative contributions to the world, we are more likely to think of the work displayed in museums and galleries than in old mine shafts and piles of bird dung. But according to researchers, those spots – plus many others – are rich in a collection of minerals that have arisen exclusively due to human activity. And this, they say, is further evidence that the current period in time can be declared the Age of Man, or the Anthropocene epoch.

To identify the minerals, Robert Hazen, research scientist at the Carnegie Institution of Washington's Geophysical Laboratory, examined each of the roughly 5,200 examples described in a catalog from the International Mineralogical Association (IMA), the body that governs what is and what isn't officially considered a mineral species. "I was surprised at how many were human-mediated," Hazen tells New Atlas.

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In all, Hazen and his team uncovered 208 minerals that were directly or indirectly created by our presence and activities on the planet. Some were created purposefully such as the silicon chips used in semiconductors or yttrium aluminum garnet crystals used in lasers. Others came about as a result of activities like mining where some minerals sprang up serendipitously on tunnel walls – such as the new uranium-rich minerals found in Utah – while others grew in mine dumps.

Andersonite forms on the walls of abandoned uranium mines in the American Southwest, glows bright green under a black light and can cost up to US$500 for a good sample (Credit: RUFF)

Some human-influenced minerals were found on corroded lead artifacts on a Tunisian shipwreck, others on bronze artifacts from Egypt, and still others in the Austrian mountains at prehistoric sacrificial burning sites. The mineral tinnunculite was formed when excrement from the Eurasian kestrel bird reacted with hot gases from a coal mine in Russia, and calclacite – first described in 1959 – was found growing inside an oak cabinet where minerals were stored at the Royal Museum of Natural History in Brussels.

Hazen and his fellow researchers contend that the sheer number of new minerals we've added to the Earth provides more evidence that we should deem our current time period as the Anthropocene epoch. An idea that's been floated for some time, proponents of the new designation say that we've impacted our planet so much, and so quickly, that it should receive a new name, rather than sticking with the current designation of Holocene, which has been around since the last Ice Age about 11,700 years ago. One of the necessary traits to define a new epoch is a change in the geologic record known as a "golden spike," and Hazen feels all our mineral-making would indeed qualify.

"The initial conclusion is that humans are responsible for a considerable number of what are supposed to be natural crystals," he told us. "But then we realized that our present time is characterized by this flood of crystals – inadvertently made and purposefully synthesized. Many of these crystals will persist for a billion years and form a marker layer in the sedimentary record that will persist for all of Earth's history. Nothing like that layer occurs in the prior 4.5 billion years of Earth. A geologist hiking a future Grand Canyon in 100 million years will find that distinctive layer littered with the new minerals and mineral-like compounds we describe."

Shannonite is formed in mine fires deliberately set to extract ore (Credit: RUFF)

In addition to the creation of new minerals, humankind has also been responsible for the large-scale transportation of minerals around the planet, especially in the form of precious and semi-precious stones and building materials transported around the globe to create roads, bridges and other structures.

"In the sediment layers left behind from our age, future mineralogists will find plentiful building materials such as bricks, cinder blocks, and cement, metal alloys such as steel, titanium, and aluminum, along with many lethal radioactive byproducts of the nuclear age," says co-author Marcus Origlieri of the University of Arizona in a statement. "They might also marvel at some beautiful manufactured gemstones, like cubic zirconia, moissanite, synthetic rubies, and many others."

An exclamation mark

Not only have we created many minerals, but the timeframe in which we've done so is striking. The researchers say that the first time great diversifying of minerals happened on Earth was over two billion years ago during "the Great Oxidation" event, a time when Earth's atmosphere became filled with oxygen, which destroyed much of the anaerobic life living on the planet at the time.

While rubies, like this one from Tanzania, grow naturally, human beings have had a hand in moving them around the planet at a never-before-seen rate (Credit: StrangerThanKindness/Wikimedia CC3.0)

"It took over 2 billion years for combinations of elements to meet naturally on Earth at a specific location, depth and temperature, and to form into the more than 5,200 minerals officially recognized today," Hazen said in a statement.

"Within that collection are 208 produced directly or indirectly by human activities, mostly since the mid-1700s, and we believe that others continue to be formed at that same relatively blazing pace," he adds. "To imagine 250 years relative to 2 billion years, that's the difference between the blink of an eye (one third of a second) and one month. Simply put, we live in an era of unparalleled inorganic compound diversification. Indeed, if the Great Oxidation eons ago was a 'punctuation event' in Earth's history, the rapid and extensive geological impact of the Anthropocene is an exclamation mark."

The paper describing the work of Hazen and his team has been published in the journal American Mineralogist.

Source: Carnegie Science

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