Monahans Sandhills State Park


Artifacts found in the sand: fulgurite.

fulgurite tubeThe ran­gers at Monahans Sandhills State Park found strange lumps rising up out of the sand. Could the lumps be fossils, rocks, or roots of an ancient tree? Turns out, they are glass tubes called fulgurites. Fulgur is Latin for lightning.

How is it made?

When lightning strikes a sand dune, the bolt passes down through the sand until its energy is exhausted. The sand melts into a glass tube along the path of the bolt. Most lightning strikes generate heat up to 50,000 degrees F, well above the tem­per­a­ture needed to melt sand.

Can this happen at your house?

All lightning strikes that hit the ground could make fulgurites, but finding one is rare. Because the sand dunes at the park are deep, the lightning strike can travel a few inches before exhausting its energy. The ground near your home is denser, plus lightning hits higher buildings and trees first.

Next time you hike, look for evidence of lightning strikes in trees, at the beach, or on top of mountains. If you find a fulgurite in the dunes, please study and enjoy it, but leave it in the sand.

And when thunder roars, head indoors!

Four fulgurites of various sizes and shapes