If you've ever hiked in the woods or picnicked in a park, you've probably heard of the concept "leave no trace." The 90s-era conservation ethics code encourages people to clean up after themselves after a stint in nature, being careful to leave no trace of their activity.
It's nice idea for personal practice, but our record as a species will not be so easily expunged from planet Earth.
Human beings have so fundamentally altered the geology of the planet, in fact, that scientists named a brand-new geologic epoch after us: the Anthropocene.
Many scientists say the Anthropocene started on July 16, 1945, when humans detonated the first atomic bomb and left a powerful chemical marker in the geological record that's detectable with radioactive isotopes. Other experts say the exact beginning may be a bit fuzzier.
Regardless of the precise date, one thing is certain: Our footprint on the planet — based at least partially on the materials we've created, moved around, or just left behind — will be visible for millions, or even billions, of years.
A new paper catalogs hundreds of these new materials for the first time, and estimates that humans are responsible for roughly 4% of all the minerals on Earth. Some formed along the slippery walls of mines, where cool, moist air reacted with sooty particles of iron ore; others were created in the depths of the ocean as ancient shipwrecks were eroded by the salty sea.
"These minerals will mark our age as different from all that came before," Edward Grew, a professor of earth and climate sciences at the University of Maine and a leading author on the new study, told Business Insider.
Put another way, humans are responsible for creating the most new minerals on Earth since oxygen first appeared in the atmosphere more than 2.2 billion years ago. Although now considered an essential component of life, oxygen's first appearance drastically altered the planet's make-up, giving rise to as many as two-thirds of the more than 5,200 minerals that are officially recognized today.
"If The Great Oxidation ... was a 'punctuation event' in Earth's history, the rapid and extensive geological impact of the Anthropocene is an exclamation mark," Robert Hazen, a mineralogist and astrobiologist at the Carnegie Institution for Science's Geophysical Laboratory, told Business Insider.
So where do these minerals come from and what do they look like?
The new study catalogs 208 new minerals that were created either principally or exclusively as a result of human activities. The vast majority are the result of one activity: mining. The dumping of ore, the build-up of water along mine tunnel walls, and fires inside mines can all contribute to this process. "When one looks at a mine, it’s really a disturbance of the Earth’s surface," said Grew.
The glowing, sea-colored mineral simonkolleite shown below was found on an copper mining tool at the Rowley Mine in Maricopa County, Arizona.
"You’re just stirring a pot in a way, exposing ores to a different environment and getting these new minerals to form," Grew added.
Dynamite explosions are being used to blast rock mass at the Olimpiada gold mine near the Siberian town of Severo-Yeniseisky (shown below). "What we're seeing...these are things that’ll persist in the geologic record that a million years from now people will find," said Hazen. "It's this incredibly rapid pulse caused by human activity."
"One could say it's a spike really," added Grew. "So such a spike would really show up in the geologic record." Other examples of that spike are this striking turquoise chalconatronite, a result of quarrying in Mont Saint-Hilaire in Quebec, Canada...
and this tan-colored, sunshine-like arrangement, which belongs to the new mineral metamunirite, discovered at a mine in Big Gypsum Valley in San Miguel County, Colorado.
Humans aren't just creating new minerals — we're also moving around existing minerals and shifting the make-up of them on the planet's surface. Millions of years from now, "people will say, 'Oh look there is clear evidence that humans have changed the geologic environment!'" Hazen said.
The abhurite shown below, for example, is a "corrosion product" from the wreck of the SS Cheerful, which sunk in 1885, and is located 14 miles northwest of St. Ives in Cornwall, England. "Minerals are very robust. They can last for millions of years," Hazen said.
Geologists of the future might also come across materials like this bronze-colored nealite, which was formed in Greece by slag (the byproduct of separating metal and ore) interacting repeatedly with water from the sea.
Or this glass-like fiedlerite, which was also uncovered at an ancient slag site in Greece.
The log of 208 new minerals in the study doesn't even include all of the mineral-like materials that humans have created. These additional materials include magnets, alloys, and building materials like bricks and concrete. Hazen estimates that there are hundreds or even thousands more of these materials littered across the terrain that researchers have yet to officially classify.
These new minerals and mineral-like materials are being redistributed across the planet. "We're talking about a pervasive layer of Earth's surface which humans have changed in fundamental ways," said Hazen.