If you work in a lab, you’ve probably used lab glass made from quartz. But you probably haven’t realized that the reason those test tubes are so durable is exactly what makes them so hard to mold.

This bespoke lab glass can withstand insane temperatures and chemical reactions because it’s made of fused quartz. That means it contains virtually none of the stuff that’s added to normal glass to make it easier to mold at lower temperatures.

Instead, this stuff is virtually pure silica, aka quartz crystals—which means that to mold it into test tubes, you need incredibly high temperatures.

GE’s Global Research in upstate New York via Gizmodo with more video shots of the process and the full article.