Sand, whether you use it for building sand castles, telling time with an hourglass, or hydraulic fracturing, is pretty much the same just about anywhere you go — an uncountable number of tiny grains mixed together to form the same dunes and beaches.
But why does sand almost always look the same? And how does so much of it end up at the beach?
Well, much of the world's sand is made out of the same stuff — tiny crystals of the mineral quartz, which is made out of silicon and oxygen, the two most common elements in Earth's crust.
And as you'll know, if you've ever bitten through the crust — of a sandwich — that had sand in it — quartz grains are small and really tough.
Here's why: Quartz crystals form within a cooling blob of molten granite rock, or magma, deep under Earth's surface.
As the magma cools, different minerals crystallize into solid rock at different temperatures, and quartz is one of the last minerals to form.
It's forced to crystallize in the tiny spaces left in the now cooling rock, pretty much ensuring that it ends up in a specific size range.
But being last has lasting advantages.
Minerals that do form in the earlier, hotter conditions have weaker chemical structures and weather away more easily than quartz, kind of like how a relationship forged in the heat of passion might not be as stable as a deep bond developed over time.
So as the weak, flash-in-the-pan minerals wear away, the unfaltering quartz grains are left to pop out of the rock as sand!
