Sand

You’re just home from the beach after a nice relaxing weekend. As you finish unpacking, you feel a sense of being well rested.

Then you notice a few grains of sand. These little hitchhikers followed you from the beach to the shower, and somehow a few of them snuck into your bag, even though you changed all your clothes and didn’t even put any of your dirty clothes into that bag!

Sand is an annoyance ninja, but what is it, really?

It turns out that sand is a lot of things. It’s a loose collection of rock fragments, minerals, and little pieces of shells, among other things. Geologists classify sand as any naturally occurring rock particle with a diameter between around 1/16 of a millimeter to 2 millimeters (this can vary slightly, but the size is the defining feature).

Here, “rock particle” does a lot of heavy lifting. Fragments of shells, quartz, feldspar, and volcanic obsidian are all very different materials with unique properties, but the whole collection mixes up and makes sand.

Some sand has made the most important innovations in human history possible. There’s glass, which comes from silica sand, the most common type. If you want to make glass, you need a relatively pure source of silica sand.

Luckily for ancient Egypt, there was plenty of sand around, including enormous amounts of pure silica sand. While it’s debated as to whether Egypt was the first to make glass more than 5000 years ago, they certainly refined the process by adding natural sources of natron, a type of salt that can help lower the melting point of glass. That lower melting point made it much, much easier to work with.

Glass was the hot technology of the day, and the silicon found in sand was the physical ingredient that made it all possible.

Then, there’s Silicon Valley. Unlike ancient Egypt, Silicon Valley in Northern California does not have a particularly high concentration of silica sand, but it did play an awful lot with silicon back in the day.

We’re not talking about a vast desert with beautiful untapped silica sand, but instead we’re talking about one of those generational innovation hubs, like Bell Labs or Edison’s Menlo Park. These places contribute more innovation and invention to the world than most of the rest of the world combined, and they only come across every few decades or so.

The key ingredient in computer chips is silicon, a chemical element found in abundance in sand. Over time, the Valley became well known for producing and manufacturing these silicon-based transistors, and even while manufacturing gradually migrated away, the name stuck: people were creating things based on a silicon-chip architecture.

Why silicon, though? Why not another abundant material for the chips, like calcium or aluminum?

It turns out that silicon has just the right electrical properties to do the job. It’s a semiconductor, which means it can conduct electricity under some conditions but not others. Even better, silicon works great at room temperature, while other potential candidates for chips like germanium don’t stand up well to heat, or they need to be super-cooled to work.

This is exactly how all those ones and zeros come to be. This is how computers work.

Silicon also happens to be the second most abundant element in the Earth’s crust, and that’s a good thing: the chip industry uses billions of metric tons of silicon every year.

Sand is an unsung material hero of the world today. It’s incredibly useful and versatile, and its all over the place.

What other wonders are hiding in plain sight like sand? It’s everywhere, and yet it’s what the modern world runs on. Help me think a little today—what else is like this?