A lightning strike that hit a soil-gravel road on a farm in Rebersburg produced a rare rock called a fulgurite. Fulgurites are lightning-induced molten rock, sand, or soil that cool and harden to form long tubes of glass. Pieces of the fulgurite were brought to the Department of Geology and Physics at Lock Haven University by a gentleman named Benuel, of Rebersburg.
Dr. Loretta Dickson, associate professor of geology, excavated the remaining fulgurite and collected samples. The rock measures 16 feet in length and has bifurcating glass branches that extend 6 feet to either side, mimicking the path of the lightning bolt as it dispersed into the ground, according to Dickson. The fulgurite glass contains gas bubbles called vesicles and the color of the glass varies in hues of black, brown and green.
“It’s exciting when we receive interesting rocks from the community because it provides an excellent opportunity for students to practice their rock and mineral identification skills and to use our state-of-the-art analytical equipment for research,” Dickson said.
Dickson has performed geochemical analyses of the glass, rock, and soil for comparison using the scanning electron microscope with energy-dispersive X-ray spectrometer housed in the Department of Geology and Physics at LHU.
“Our initial geochemical analyses show that the chemical composition of the fulgurite glass is the same as the chemical composition of the gravel from the road,” Dickson said. “The data suggests that the soil-gravel material melted to form the fulgurite glass.”
The temperature of air in a lightning channel may reach up to 50,000 degrees. When lightning strikes the ground, it experiences an enormous and instantaneous increase in temperature and melts, according to Dickson.
“The fulgurite find in Rebersburg is unique because the impact from the lightning was so intense that molten globules were thrown into the air to land as much as 9 feet away in contorted blobs on the ground,” Dickson said.
Large fulgurites are poorly documented in the scientific literature and Dickson said soil-rock fulgurites might be more common than most may think. “When lightning strikes the ground, a fulgurite is most likely formed, but maybe people are not looking for them, or don’t know what they have found if they come across a long tube of glassy rock,” she said.
Dickson plans to continue to work with LHU geology majors to gain more insight into the rare rock discovery.
Sign-up for LHU’s new monthly newsletter, LHU & You, to get all of your updates on The Haven and the Lock Haven community. Click here to sign up
Lock Haven University is a member of Pennsylvania’s State System, the largest provider of higher education in the Commonwealth. Its 14 universities offer more than 2,300 degree and certificate programs in more than 530 academic areas of study. Nearly 520,000 system alumni live and work in Pennsylvania.
Questions About the Article?
Executive Director of Communications and Community Relations
Contact our Admissions Office
8:00am to 4:00pm Monday-Friday