Tikalon Blog by Dev Gualtieri

Anthropocene Minerals

August 16, 2021

Tikalon's location on Northern New Jersey is a geologically interesting place. Route 80, an interstate highway, is just a mile from my house, and this highway was cut through terrain that reveals the sedimentary layers laid down through the ages. These are quite apparent at the Delaware Water Gap at the border between New Jersey and Pennsylvania. Sedimentary layers there are from the Silurian (443.8-419.2 million years ago) and Ordovician (485.4-443.8 million years ago) geological periods. The fossil fauna record of the Silurian consists of mostly marine animals, and a few small terrestrial animals, such as the millipede, Pneumodesmus.

Geological regions of the Great Appalachian Valley. highway excavation through these areas reveal the sedimentary layers of the Silurian and Ordovician geological periods. (Created using Inkscape from a Wikimedia Commons map of the United States by Elli and a Wikimedia Commons map of the Appalachian Mountain physiographic regions by Perhelion. Click for larger image.)

Nicholas Steno, a Catholic priest, initiated the science of stratigraphy in his Dissertationis prodromusa, a 1669 treatise on the fossilization of organic remains in sedimentary layers. He noted that each horizontal layer records a particular period of time. The idea that strata, the layers one atop another at Earth's surface, contain a record of Earth's history was more completely developed in the 18th century. William Smith (1769-1839) studied strata and their fossil markers to create the first geologic map of England.

Along with the fossil record of the development of life on Earth, strata also contain evidence of global catastrophes, such as the extinction of the dinosaurs by a meteor impact about 65 million years ago. The is evidenced by an excess of iridium in a clay layer at the boundary between the Cretaceous and Tertiary strata.[1-2] Iridium is a rare element existing as just 0.001 ppm by weight in Earth's crust, which is forty times less of an abundance than gold. The clay layer has a concentration of iridium that's two orders of magnitude greater than this, which is consistent with a meteor source.[1-2]

If the impact of this 10 kilometer meteor is so easily seen in the geological strata, what of the affect of human technology? Geologists have struggled since the turn of this century to define a definite geological starting point for the Anthropocene, the period defined by significant human impact on the geology and ecosystems of the Earth.[3-5] It's readily apparent that present conditions differ greatly from those of the Holocene, the geological period begun 11,700 years ago in which we live.[3] At this writing, neither of the two major geological organizations, the International Commission on Stratigraphy and the International Union of Geological Sciences, have an official definition for the Anthropocene.

An Anthropocene Working Group of the International Commission on Stratigraphy is considering potential stratigraphic markers for a mid-twentieth century start of the Anthropocene. The mid-twentieth century was a time of dramatic socioeconomic and environmental changes, called the Great Acceleration, which includes the Atomic Age. Other proposed starting points of the Anthropocene include the beginning of the Agricultural Revolution, 12,000–15,000 years ago. Nobel Laureate, Paul Crutzen, who originated the Anthropocene term, proposed its beginning in the late 18th century with the commencement of the Industrial Revolution. My favorite marker of the Anthropocene is the husbandry of chickens.[6] Chickens have been a considerable accelerant of civilization.

The husbandry of chickens, which are an easily raised source of meat with the added benefit of eggs, did much to advance civilization. Americans eat nearly a hundred pounds of chicken annually, which is more than pork or beef.

Chicken's mild taste is a perfect vehicle for culinary art, producing varied offering from chicken tikka masala to Kentucky Fried Chicken.

The wild progenitor of our domestic chicken is the red junglefowl (Gallus gallus). Charles Darwin made this determination, which has been confirmed by DNA analysis.

(Portion of a Wikimedia Commons image.)

Some argue that the Anthropocene should encompass the full span of human existence dating long before agriculture.[3] However, geological markers should be easily discovered, and modern technology has produced many geological artifacts. As University of Leicester (Leicester, UK) geologist, Jan Zalasiewicz, explains, "The greatest changes, of population, industrialization, globalization have taken place with the 'Great Acceleration' of the boom post-WWII years of the mid-20th century."[4] His Leicester colleague, Mark Williams, remarks that "In that brief spell--a little less than one average human lifetime--humanity has burned through more energy than in the previous 12 millennia and more."[4] Humans are driving the physical, chemical and biological changes that are destabilizing the biosphere and climate, and the modern-day strata contains plastics, concrete and supermarket chicken bones that act as easy markers for the Anthropocene."[4]

One research team has quantified some processes affected by human activity, as shown in Table I.[5]

Table I. The Anthropocene by the numbers. Ratios of process outcomes, human/natural causes. Data from fig. 2 of Ref. 5.[5]

Process	Ratio	Description
Deforestation	2	Forest loss/loss from wildfires
Animal Husbandry	30	Mass of barnyard animals/mass of wild animals
Earth Moving	15	Mass of earth moved/mass moved by rivers
CO₂	2	Mass of CO₂/mass from natural sources
CH₄	1	Mass of CH₄/mass from natural sources
Extinction	10	Actual/expected

In 2017, Robert M. Hazen of the Geophysical Laboratory of the Carnegie Institution for Science (Washington, D.C.), Edward S. Grew of the University of Maine (Orono, Maine), along with Marcus J. Origlieri and Robert T. Downs of the University of Arizona (Tucson, Arizona) published a different way to identify the Anthropocene.[7-8] They argue that mining and manufacturing operations since the industrial revolution have caused a spike in the diversity and distribution of mineral-like compounds.[8] They cataloged 208 mineral species that occur principally or exclusively as a result of human activity.[7-8] This number is more than 3.5% of the 5700 minerals officially recognized by the International Mineralogical Association.[8-9]

As Hazen explains,

"Mineral evolution has continued throughout Earth's history. It has taken 4.5 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... Within that collection of 5,200 are 208 minerals 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. 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."[8]

The research team identified three major types of human activities that have affected the stratigraphic mineral record. The first, and most obvious factor is the inclusion of many synthetic minerals, such as yttrium aluminum garnet (YAG) crystals for lasers, silicon and other semiconductors, Portland cement, carbide abrasives, and specialty magnetic alloys such as neodymium iron boride.[8] Second is the large-scale movements of rocks and sediments from their original location for things such as road construction in a manner that's much faster than the natural redistribution caused by glaciers.[8]

Simonkolleite, one of 208 anthropogenic minerals.

Simonkolleite [Zn₅(OH)₈Cl₂·H₂O] is a copper mining artifact, found in the Rowley mine, Maricopa County, Arizona.

(Photo credit: RRUFF Project. Click for larger image.)

The third human activity apparent in the recent stratigraphic mineral record is the human redistribution of select natural minerals, such as the gemstones, diamond, ruby, emerald, and sapphire, along with concentrations of gold, silver, and platinum.[8] Mineral collections juxtapose mineral species in unnatural combination.[8] As study co-author, Marcus Origlieri of the University of Arizona summarizes,

"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. They might also marvel at some beautiful manufactured gemstones, like cubic zirconia, moissanite, synthetic rubies, and many others."[8]

Anthropocene Minerals

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