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.

Som…