The global economy depends on a single road in Spruce Pine, North Carolina.

tomshardware.com/tech-industry/semiconductors/the-worlds-semiconductor-industry-hinges-on-a-quartz-factory-in-north-carolina

That road leads to a mine producing the purest quartz in the world, and the factory that processes it. There is no naturally occurring alternative source.

The quartz is used to create crucibles which are used to produced silicon wafers, which are in turn sliced and cooked and dice to produce computer chips.

It is possible to make the quartz synthetically; we just don't right now because its very costly and there's an enormous pile of it sitting underground in this one spot that can mined cheaply. But it would be a few difficult years if anything happened there.