Busting Illegal Sand Miners With Sand “Fingerprinting”

“I don’t like sand. It’s all coarse, and rough, and irritating. And it gets everywhere.” –Anakin Skywalker

Most people don’t take sand very seriously. We tell people to “pound sand” when we don’t like them. We use sand to illustrate great numbers of things, like when Carl Sagan said there are more stars in the universe than grains of sand on our planet. The stuff is literally everywhere. Nobody thinks of rarity when they think of sand.

There’s a problem, though. In some places they’re actually running out of the stuff. No joke.

The earth is always making sand. You can find geologic processes making it in rivers, under and near oceans, and blowing around in deserts. The thing is, we’re using it about twice as fast as nature makes it, because we use it for a lot of things. For one, we build lots of things with concrete, and sand is one of the main ingredients. We use it to make glass, abrasives, and electronics. We use it as filler to “frack” for oil. As population grows and more technologies rely on sand, we are only using more of the stuff while the new supply of sand doesn’t go up.

Around 85% of all mining is for sand, and China is the biggest buyer of sand, using about 60% of it.

When we take away too much sand from a place, it causes real problems for both the environment and for humans. This is probably worst in rivers, which also happen to be a source of the best sands for many industrial purposes. While we’re using it twice as fast as we get it globally, we’re using it 40 times faster than it’s made in rivers. When we take too much, all hell breaks loose. Habitats get destroyed, rivers change course, and even water tables are affected (sand filters water, and helps hold it). Without access to good water, people can’t grow food, and that’s something we definitely can’t find on the used market.

Sand miners in India use a boat to transport their product. Wikimedia Commons.

In response, some countries ban sand mining from rivers. Because losing too much sand can cause a variety of problems, like less drinking water for humans, there’s great local motivation to ban sand mining in some areas. The problem, though, is that regulations are local, and the buyers of sand might be from a different region or continent.

Tracking down the source of sand is a real challenge. You can buy it from a supplier, who might get it from a lot of different places, and might not even know where in the world it came from. Locally, there may even be motivation to lie about where the sand came from, because that would get in the way of making money. It’s even worse when a river with a sand mining ban gives more desirable sand than other places. According to one geologist, the “immature” sands in rivers are the most desirable for many industrial processes.

Geologists are now suggesting we “fingerprint” sand. While it might seem like it’s always the same stuff, sand can differ a lot depending on where it came from. Some sands are better suited for filtering water. Others might be better for making laptop screens. During the 2020 Geological Society of America Annual Meeting, geologists suggested taking a closer look at the sand people are buying.

“There’s no reason why I couldn’t go take a core of concrete of an existing skyscraper and take that same compositional signature and tie it back to a source,” said Zachary Sickmann, a geologist at U.T. Austin. the geology of Southeast Asia and South Asia is complex, and should provide a lot of leverage in distinguishing sand from different regional areas of concern.”

In other words, geologists can take sand samples from places with a sand mining ban, and then check sand for sale in different places to see where the sand came from by taking a closer look. The minerals from one region or even one river valley can vary enough from other sand nearby for geologists to positively identify the sand. Sickmann says that it’s possible to determine which river produced a truckload of sand, but “the real crux of the issue is finding the most effective way to use the method in a regulatory capacity.”

To make sand “fingerprinting” cost effective, geologists are going to start by analyzing sand in the United States, where sources and destinations are well known. Next, they’ll work with colleagues from around the country to collect and catalog sand from home improvement stores around the country. Finally, they’ll work to see if they can figure out where the sand came from and see if they got it right.

Once they get some experience identifying sand from different regions of the United States, they’ll be able to use their experiences to identify sand in other regions with greater accuracy and with less work, which will translate to less guesswork and ultimately lower costs.

“This is a very important issue,” said Aurora Torres, the study’s coauthor. “I see this as a valuable tool that will be that will complement other strategies that are being put in place to track and monitor these illicit supply networks.”

By equipping officials and geologists in developing countries with the tools and know-how they need to analyze sand in their countries, it will be much easier for those places to actually enforce bans on illegal sand mining. Not only will that help stabilize water supplies and critical habitats along the rivers, but it will help humans keep good access to drinking water and agricultural resources.

More information and contact info for the researchers can be found in this Geological Society of America press release.

The Geological Society of America, founded in 1888, is a scientific society with members from academia, government, and industry in more than 100 countries. Through its meetings, publications, and programs, GSA enhances the professional growth of its members and promotes the geosciences in the service of humankind. Headquartered in Boulder, Colorado, USA, GSA encourages cooperative research among earth, life, planetary, and social scientists, fosters public dialogue on geoscience issues, and supports all levels of earth science education.