Ever since the early years of human civilization, the biodiversity of our planet has been profoundly influenced by human activities. This phenomenon (along with climate change, selective breeding and other human-derived evolutionary pressures, and human-mediated invasive species) is an oft-cited example of how we, as humans, are causing our surroundings to shift in considerable ways.
A recent paper (PDF) authored by Robert Hazen of the Carnegie Institution for Science along with Edward Grew, Marcus Origlieri, and Robert Down, however, is illuminating the influence humans have on a less-celebrated aspect of the local and global environment: the mineral diversity of Earth.
Mineral diversity and evolution aren’t exactly household concepts like ‘biodiversity’ and ‘climate change’. It’s easy to find media coverage related to melting polar ice and the discovery (or extinction) of species around the globe, but there appears to be far less popular intrigue related to human-mediated shifts in our planet’s mineral diversity. If media-coverage is the primary metric by which popular interest is measured, then humanity’s interest in minerals is generally confined to metals and metal alloys which have either aesthetic or technical value (e.g. gold, platinum, titanium, silver, lithium, etc.) and to gemstones. Society has collectively failed to bat an eye at the emergence of any new minerals lacking popular appeal and I’m sure many people would be surprised to learn that while mankind was busy rushing for gold and using diamonds to fuel war machines and adorn jewelry, at least 208 minerals were ushered into existence either principally or exclusively as the direct result of human activity.
In their paper, Hazen, Grew, Origlieri, and Down describe how they meticulously searched through the available literature and the records of the International Mineralogical Association (and here) and discovered a host of examples of this phenomenon.
Perhaps not surprisingly, a substantial portion of these mineral species were linked to mining activities. The researchers identified seven mine-related categories under which more than 80 minerals that have no known natural occurrence could be classified. In other words, their emergence is believed to be the direct result of human activity and such minerals would likely not have occurred at this time in Earth’s history without human mediation. Those categories are:
- Alteration of phases due to ore dumps
- Alteration of phases associated with mine tunnel walls
- Mine water precipitates
- Minerals found in slag or the walls of smelters
- Minerals associated with mind dump fires
- Interaction with mine timbers or leaf litter
- Minerals associated with geothermal piping systems
Some of the minerals identified under these categories include:
Schuetteite – Alteration phase recovered from ore dump. Found in an ocean mine dump in San Luis Obispo County, California.
Hoganite – Interaction with mine timbers or leaf litter. Found in the Potosi mine in Broken Hill, Australia.
Ferrarisite – Mine water precipitate. Found in Gabe Gottes mine in Alsace, France. This is a very old mine site, with its first discovery dating back to 1549.
Hughesite – Alteration phase associated with mine tunnel walls. Found in the Sunday mine in San Miguel County, Colorado.
Cuprospinel – Associated with mine dump fires. Found in the Consolidated Rambler mine in Newfoundland, Canada.
Fiedlerite – Associated with slag. Found in an ancient mine slag heap in Lavrion, Greece.
Outside of mining-related phenomena were a small selection of minerals that arose from rather unusual circumstances. For example, there was Calclarite which was found to have formed in museum storage cabinets and Abhurite which was associated with the alteration of tin archaeological artifacts and found in the wreck of the SS Cheerful, 14 miles NNW of St. Ives, Cornwall, England..
The paper also provided descriptions of more than 100 minerals with known natural occurrences that have were formed outside of their natural distributions due to human processes. While many of these minerals were also related to mining activities, seven minerals were related to the alteration of lead, bronze, and tin artifacts and four were discovered to have arisen due the activities as sacrificial burning sites. Archaeology and cultural ritual as a driver of mineral diversity. Fascinating!
By bringing substances in contact with each other which wouldn’t have the opportunity to interact (at this point in Earth’s history) were it not for human activities, mankind is influencing the pressures of mineralogical evolution in the same manner it is influencing the pressures of biologic evolution.
The authors also point-out the profound influence that mankind is having on Earth’s geological record (and perhaps that of the extra-terrestrial geologic record) through the development of synthetic compounds which, by their very nature as ‘man-made’, are not classified as minerals. For instance, in their own words,
Prior to human activities, the most significant “punctuation event” in the diversity of crystalline compounds on Earth followed the Great Oxidation Event. Hazen et al. (2008) estimated that as many as two-thirds of Earth’s more than 5000 mineral species arose as a consequence of the biologically mediated rise of oxygen at ~2.4 to 2.2 Ga. By comparison, the production of the more than 180 000 inorganic crystalline compounds (as tabulated in the Inorganic Crystal Structure Database; http://icsd.fiz-karlsruhe.de) reflects a far more extensive and rapid punctuation event. Human ingenuity has led to a host of crystalline compounds that never before existed in the solar system, and perhaps in the universe. Thus, from a materials perspective (and in contrast to Earth’s vulnerable biodiversity), the Anthropocene Epoch is an era of unparalleled inorganic compound diversification.
Like the authors, I wonder if these alterations will be enough to help advance that argument that we, as humanity, are creating a true “Anthropocene Epoch”. A distinct period with a lasting impression in the geologic record defined by our ‘human bioturbation’ (Zalasiewicz et al. (2014)). At the very least, the paper’s illuminating findings demonstrate the profound power that humans wield in our current form. Prior to this point, the dominant driver of biotic and abiotic diversity was the Earth itself and we seem to be rending that responsibility from its grasp.