Lightning also has the power to make glass.

When lightning strikes the ground, it fuses sand in the soil into tubes of glass called fulgurites.

L. Carion/Carion Minerals, Paris

When a bolt of lightning strikes a sandy surface, the electricity can melt the sand. This melted substance combines with other materials. Then it hardens into lumps of glass called fulgurites. (Fulgur is the Latin word for lightning.)

Now, scientists are studying fulgurites in Egypt to piece together a history of the region’s climate.

Thunderstorms are rare in the desert of southwest Egypt. Between 1998 and 2005, satellites in space detected hardly any lightning in the area.

Amid the region’s sandy dunes, however, fulgurites are common. These lumps and tubes of glass suggest that lightning used to strike there more often in the past.

Recently, scientists from the National Autonomous University of Mexico in Mexico City studied fulgurites that had been collected in Egypt in 1999.

When heated, minerals in fulgurites glow. Over time, exposure to natural radiation causes small defects in the glassy fulgurites. The older the material is, the more defects there are, and the stronger the minerals glow at certain wavelengths of light when they’re heated. By measuring the intensity of the glow when the samples were heated, the researchers found that the fulgurites formed around 15,000 years ago.

The gases trapped in bubbles within samples of fulgurite provide clues to ancient soil and atmospheric chemistry and climate.

Rafael Navarro-González

The scientists, for the first time, also looked at the gases trapped inside bubbles in the glass. Their chemical analyses showed that the landscape could have supported shrubs and grasses 15,000 years ago. Now, there’s only sand.

Today, shrubs and grasses grow in the hot, dry climate of Niger, 600 kilometers (375 miles) south of the Egypt site. The researchers suspect that, when the fulgurites were created, the climate in southwest Egypt was similar to present-day conditions in Niger.

Fulgurites and their gas bubbles are good windows into the past, scientists say, because such glasses remain stable over time.

Analyzing the Egyptian fulgurites, in particular, is “an interesting way of showing that the climate in this region has changed,” says Kenneth E. Pickering, an atmospheric scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md.

Even if you’re afraid of thunderstorms, the amazing powers of lightning are bound to impress you! And lightning strikes can even tell a story of ancient times.—E. Sohn

Going Deeper:

Perkins, Sid. 2007. Stroke of good fortune: A wealth of data from petrified lightning. Science News 171(Feb. 17):101. Available at http://www.sciencenews.org/articles/20070217/fob5.asp .

You can learn more about fulgurites at en.wikipedia.org/wiki/Fulgurite (Wikipedia).

Now, researchers from London and Germany have found evidence that the Egyptians were making their own glass as far back as 3,250 years ago. The discovery defies a longstanding theory that ancient Egyptians imported glass from Mesopotamia.

Archaeologists have found a variety of items used in glassmaking, including this ceramic container, at an ancient Egyptian glass factory. Glass was colored and heated in this vessel, which is about 7 inches across. The inset shows glass ingots from a Bron

© Science

The oldest known remnants of glass come from an archaeological site in Mesopotamia. The shards are 3,500 years old, and many experts assumed that this site was the source of fancy glass items found in ancient Egypt.

The new evidence, uncovered in an Egyptian village named Qantir, however, shows that an ancient glassmaking factory had operated there. Artifacts from Qantir include pottery containers holding glass chunks, along with other traces of the glassmaking process.

This piece is all that remains of a clay funnel used to help pour glass powder into a ceramic vessel.

© Science

Chemical studies of the remains suggest how the Egyptians made their glass, the researchers say. First, the ancient glassmakers crushed quartz pebbles together with the ashes of burnt plants. Next, they heated this mixture at low temperatures in small clay jars to turn it into a glassy blob. Then, they ground the material into powder before cleaning it and using metal-containing chemicals to color it red or blue.

In the second part of the process, the glassworkers poured this refined powder through clay funnels into ceramic containers. They heated the powder to high temperatures. After it cooled, they broke the containers and removed solid disks of glass.

Egyptian glassmakers probably sold and shipped their glass to workshops throughout the Mediterranean. Artisans could then reheat the material and shape it into fancy objects.

This map shows the Egyptian village Qantir, where a glass factory was located, and trade routes that would have carried glass from the Nile Delta to other parts of the Mediterranean.

© Science

Now that glass is so easy to come by, it might be hard to imagine how special it was back then. At the time, wealthy people exchanged sculpted glass pieces as a way to make political bonds with each other. If you hand someone a piece of glass today, they’d probably just toss it in a recycling container!—E. Sohn

Going Deeper:

Bower, Bruce. 2005. Ancient glassmakers: Egyptians crafted ingots for Mediterranean trade. Science News 167(June 18):388. Available at http://www.sciencenews.org/articles/20050618/fob3.asp .