Lightning Rocks - Fulgurites

[1dave]

When lightning hits the ground it usually melts and vaporizes rocks. If it hits on a sandy beach the bolt is usually broken up and scattered, making lots of little tubes in the soil.



BUT when there is something tall in the vicinity the full power of the bolt may be drawn to a single point:




Lightning Discharge in Limestone

@rockpowell and I stumbled upon a power pole several years ago that is often struck.



My first collection was found scattered all over the dirt road.

[1dave]

Jul 13, 2014 17:51:00 GMT -7 @jamesp said:

The lightning density has some relationship w/sand. The little point of yellow crossing south Georgia line into Florida has good clay content.
Said to have washed down from north Georgia. Covering the ancient coral reefs w/clay to assist silicification.
It is my coral turf.

[1dave]

Jul 13, 2014 17:35:00 GMT -7 @jamesp said:

Maybe a thick copper wire connected to a tall bamboo pole stuck in the ground out in an open field would manufacture some for you Dave.

Power poles have a ground wire on them, is that what made the ones you found ?

Zgzack-l-fit !
As storm systems swirl around they are huge static electric generators sucking electrons up into the clouds.

The clouds act as capacitors.







Anything moves and the electricity ionizes the area and the electrons balance things out.

The ground currents move beneath the clouds.
Here, the + reaching up the pole, and the - reaching down from the clouds joined up and ionized a path to the ground rod. I suspect in this case, power from the lines joined in the ionized fray and helped blast up rocks from around the ground rod.
Material turning into gas expands hugely in volume and blasted much of it onto the road.

I dug around the ground rod and pulled out bowling ball sized pieces.

[1dave]

Jul 13, 2014 20:33:01 GMT -7 @jamesp said:

I never have looked for them. Glad I know what to look for. Sounds like you found a real honey hole.
artificially made ones :

[1dave]

Jul 14, 2014 9:20:52 GMT -7 @rocks2dust said:

They can be found around the tops of mountains and buttes out west if there is ashy or sandy soil present instead of only boulders. Those high points do get a lot of strikes over time.

[1dave]

Aug 9, 2017 15:58:37 GMT -7 @captbob said:

Folks from University of Florida dug up one that was 17 feet long awhile back. Think that was the record.

news.ufl.edu/archive/1997/05/experts-from-uf-dig-up-worlds-longest-solidified-lightning-bolt.php

Experts From UF Dig Up World’s Longest Solidified Lightning Bolt

May 19, 1997

GAINESVILLE — When researchers from the University of Florida began digging into the ground where a lightning bolt had hit, they thought it would be just another minor excavation.

But the longer they worked, digging along the glassy path left behind by the dirt-melting lightning, the more apparent it became that this was no ordinary dig. What they finally unearthed was verified recently by the Guinness Book of Records as the world’s longest fulgurite ever excavated.

“There isn’t much known about fulgurites,” said Martin Uman, chairman of UF’s electrical and computer engineering department and a member of the research team. “It’s very exciting for us to have been able to find this one. But I’m sure there are longer ones out there waiting to be discovered.”

The record-breaking fulgurite includes two branches, one almost 16 feet long and the other reaching 17 feet.

This will mark the first time Guinness includes the fulgurite category in its data base of records. Guinness spent six weeks researching the topic until it confirmed that the UF discovery is the longest on record. The closest is a 13-foot fulgurite currently housed in a museum.

Uman and his team began excavating last summer after a bolt struck the ground at Camp Blanding, near Starke, where UF maintains a lightning research facility by agreement with the U.S. Army National Guard.

“This strike kicked up a lot of dirt and made some fire,” Uman said. “Observers as well as surveillance cameras spotted the lightning, and a flag was placed in the ground on the burn mark.”

Fulgurites have been described by some as solidified lightning bolts. They are glassy tubes that lightning forms below the ground as it tears through the soil. The lightning melts the sand, which solidifies again when it cools to form the hollow glassy material.

Daniel Cordier, formerly of UF’s geology department, supervised the excavation and did most of the digging and removal of the fulgurite.

“If a normal citizen tries to dig one of these out of the ground,” Uman said, “they would destroy it because fulgurites are so fragile. It takes experts who are skilled in working with special tools and are used to digging up fossil bones. It’s definitely an art.”

UF’s facility at Camp Blanding was established in an effort to understand lightning and how it affects electrical power sources. The research has shown that underground power systems can be struck by lightning because the strike keeps moving below the surface.

Uman said the fulgurite, intact with its two branches, probably will go to a museum. Several have expressed an interest, but the location must be large enough to appropriately display it in its original form, he said.

Although the lightning facility was not intended for fulgurite research, Uman said interest in the underground lightning bolts has grown during the last few years.

“We have dug up a lot of fulgurites,” said Uman. “A rather large one of ours is now on display at the Electric Power Research Institute in Palo Alto, Calif.”

A 10-foot fulgurite is being prepared for display in the lobby of UF’s new engineering building. Uman said the team will continue looking for record-breaking fulgurites.

“We’ll keep looking for a longer one,” Uman said. “We may keep digging these things up forever. It’s fun.”
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