A microscopic look at why the world is running out of sand

Humans are using more sand than the Earth is naturally producing, and that’s a problem for the global construction industry. But it turns out that the usefulness of sand depends on the science of each tiny little grain. We went on a sand scavenger hunt to collect some samples, look at them under a microscope, and try to figure out why sand scarcity is such a problem. 

The Amazing Life of Sand | Deep Look

There's a story in every grain of sand: tales of life and death, fire and water. If you scooped up a handful of sand from every beach, you'd have a history of the world sifting through your fingers 

The Sand Lab

Sand!

Tonny Brinkman: Sand Collector

Sand collector Tonny Brinkman has generously donated 3500 sands to Auckland Museum - and her decades of collecting show that you can explore the world without going far from home. As the motto of International Sand Collectors Society says: 'Discovering the World, Grain by Grain'. 

Tonny (Antonia) Brinkman was born in The Netherlands in 1924, came to New Zealand in 1963, and today lives in Henderson. She began collecting in 1977 and by collecting and swapping with others has a huge collection of not just sand, but also rocks and minerals. With the latter she won many prizes at rock and mineral shows. These are now disbursed to family, the Matakohe Kauri Museum, and some are in Auckland Museum’s Brinkman Collection. Tonny clearly derived a lot of pleasure and gained great knowledge of other places by swapping with people from all over the world, learning about where the sand came from and why. Without the advantage of the internet it was mostly done via the postal system and use of the library. Some of the overseas collectors sent detailed maps and diagrams of exactly when and where the sand was collected. Unlike many collectors Tonny meticulously noted and recorded details of each sample which are labelled accordingly. This is what makes the Brinkman Collection scientifically valuable. Phew, so much work! 

Thanks to the generous donation of Tonny, the Museum now has a huge collection of sands (over 3500) from Antarctica to Norway and from New Zealand to Australia, Africa and South America.  

Sentiments for sediments People who love sand are called arenophiles, from the Latin arena for sand or sandy area, such as the floor of the Colosseum in Rome (hence our use of the word today for sports facilities). A geologist who studies arenaceous sediment is called a sedimentologist. What is sand? 

To a geologist or sedimentologist sand is particulate material ranging in size from 0.063 to 2 millimetres in size. It can be derived from the weathering and erosion of any rock (igneous, metamorphic or sedimentary), or it could be a volcanic ash, or be derived from the breakdown of marine organisms (e.g. Coromandel beach shell sand), or is produced by microscopic animals and plants such as foraminifera (e.g. tropical beaches), or diatoms (e.g. fresh water lakes), or be chemical 'precipitates' (e.g. tropical oolites). 

 Natural processes will sort and concentrate sand-sized particles by size, density and durability giving rise to some unique and beautiful sands. For example the green olivine-rich sands of Hawaii, red garnet-rich sands of Southland, black magnetic iron oxide-rich sands along the West Coast of New Zealand or the golden quartz-rich desert sands of uniform grain size sorted by the wind in arid climates. Tonny's collection includes examples of all of these from a huge range of environments (deserts, beaches, rivers, lakes, volcanoes, submarine environments and human processing of materials). Probably the only place she doesn't have sand from is other parts of the solar system or the Universe!  

Why is the collection important? The aesthetic beauty of the sands aside, Tonny's collection has great untapped research potential. Firstly they are an archive of what a given area used to be like and can be used to document change or impacts. Those who study sedimentary rocks would find them useful palaeoenvironmental indicators since 'the present is a key to the past'. For example a sandstone may have an unusual grain-size distribution or mineralogy that can be matched to one of Tonny's samples. So the modern sand and its data could be used as an analogue to tell us what the environment was like when the ancient sediments were being deposited millions of years ago. 

 The samples could even be used forensically. Sand can stick to tyres and be found inside vehicles, footwear or clothing. Despite denials, matching the suspect sediment to Tonny's sand library might well tell us where someone had been recently - literally anywhere in the world. A similar technique was used to help convict some of the French agents responsible for the Rainbow Warrior bombing in 1985. 

At the very least, just holding a container of sand from an exotic place and using your imagination can transport you there.

Secret Confessions of A Sand Collector

Secret Confessions of A Sand Collector by Justine E. Hausheer.

Sand Collecting 101 

Admit it, you’re at least mildly curious now. 

So where does a new sand collector start? 

Know the rules: Do your research ahead of time and understand where you are allowed to collect samples. Regulations vary depending on location, and you might have to do some digging (pun intended) to determine if collecting is allowed or seek permission from a landowner. If you’re collecting overseas and transporting samples across international borders, it’s also worth checking the customs regulations. Sand and rocks are inorganic materials, so theoretically they shouldn’t be a biosecurity hazard. But good luck trying to explain that to a cranky TSA agent… trust me, it doesn’t work. (Most of my own collection is now stored in a closet in my childhood home, as I couldn’t legally import them into Australia.) 

Don’t disturb the local ecosystem: Much of this is common sense, but it bears repeating: Only take a small amount of sand — you don’t need a bucket’s worth. Don’t dig large holes, step on plants, dig up animal burrows, or wander off the trail onto fragile soils. 

Keep your eyes open: Sands of different textures, colors and composition can often be found quite close to one another. Sometimes it can be hard to see these differences in situ, depending on the lighting. When in doubt, take a sample.

Bring your collecting kit: You don’t need much to collect your own sand samples. I carry a handful of small ziplock bags, each marked with a number (1, 2, 3…). When I collect a sample I jot down the bag number and details about the location in my phone. For those who like a little more specificity, you can record a GPS coordinate instead. You can also simply mark that information on the bags as you go, but I prefer to rinse and reuse my bags a few times to cut down on my plastic consumption. In a pinch, a waterbottle is always handy, even if it means finishing your hike a bit thirsty. And if you’re collecting wet sand, take a little bit more than you think you’ll need, as the sand will reduce in volume as it dries.  

Decide how you will document and display: Options abound when it comes to storing your collection. Some collectors maximize their space by storing samples in identical containers, often with custom storage racks or drawers. (You can find hundreds of options from wholesale container and lab supply stores.) Others opt for a more artistic look, using a variety of glass bottles of different sizes and shapes. I used to prefer small, glass apothecary bottles sourced from thrift shops and antique markets. But I’m eyeing a to transition to the uniform, bulk-order bottle approach very soon, as my collection grows and becomes more difficult to store and transport during moves. Whatever containers you choose, make sure your sand is dry before you store it. I dry mine on a cookie sheet in the sun (or the oven) and then filter it through a kitchen sieve to remove any bits of organic material, like, seeds, grass, etc. Then I use a funnel to decant the final sample into a bottle.  

Label, label, LABEL: I can’t stress this enough… label your sand! Small craft tags, basic white printer labels, sharpies — use whatever you like, as long as you can keep track of where and when you collected the sand in each bottle. Serious collectors will often photograph and log each sample in a digital database or spreadsheet.  

Embrace your inner substrate nerd: And perhaps most important of all — stay curious. Turn the next corner, get your hands dirty, and enjoy an oft-overlooked geological wonder.