Fulgurite

| 19 Comments

Photograph by Virginia Pasek.

Photography contest, finalist in the “Minerals” category.

Pasek.Fulgurite3.jpg

Fulgurite – Glass formed as lightning strikes sand or soil. Phosphate-containing sand was fused and turned into phosphite. This otherwise unknown natural phosphite explains the existence of phosphite-eating bacteria. In the center is a small granitic pebble that was trapped during the formation of the glass. A bolt of electricity traveled along its surface, leaving permanent evidence of its passage. Tucson, Arizona, 2007.

19 Comments

Is this one of the photo contest pics?

What a pretty example of opportunistic branching, also known as percolation, in physics.

Evolution does the same thing.

Is this one of the photo contest pics?

Yes:

We will display one of the 6 finalists in the mineral category every day at 12:00 noon, Central Daylight Time, for 6 days, beginning Monday, August 10.

But I have added an explicit statement to the pictures.

Is that a typo in the name of the person who submitted the picture (should it be Virginia instead of Virginai)?

I thought it probably was, but you do post pretty pictures quite regularly so I thought I’d ask :)

(should it be Virginia instead of Virginai)?

Sigh.

I have found this petrified lightning in some badlands in Wyoming. Usually atop a ridge and usually in a layer with a high ration of sand to the ubiquitous red clay and gray loess.

It is quite amusing to pick up what looks like a small piece of an unfamiliar conglomerate and find it has roots. Like pulling brambles.

The ones I found were rather fragile. Handling them was enough to simulate decades of erosion. No specimens were retrieved intact.

The cool part was to trace the length and extent of the branchings and bifurcations. I recall one that seemed to occupy a circular area of at least fifteen feet. Because of the steepness of the terrain I never found it all.

I did come home with some nice fossil snails, though.

Gee, Matt. I didn’t mean to intrude. Or are you my long lost co-joined twin?

*never saw two consecutive comments in the same color field.*

Ignore that last. Maybe my browser didn’t render the page correctly. When my comment was accepted it was within a blue rectangle that contains Matt’s comment above. It struck me as odd.

Once I posted my apology the three comments were all snug in their own color coded keeps.

All’s well. I guess. I notice that someone has been playing with the code.

Mike Elzinga said:

What a pretty example of opportunistic branching, also known as percolation, in physics.

Evolution does the same thing.

And if you look closely it spells “Hitler.”

Don’t laugh, that might be the DI’s next strategy.

Frank J said:

And if you look closely it spells “Hitler.”

Don’t laugh, that might be the DI’s next strategy.

Ah, yes; of course!

Lightning = Blitz = Blitzkrieg = Nazi Germany = Hitler.

Crudely Wrott said:

The ones I found were rather fragile. Handling them was enough to simulate decades of erosion. No specimens were retrieved intact.

There must be a way to preserve them for transport. Shellac? Plaster? Bondfast?

fnxtr said:

Crudely Wrott said:

The ones I found were rather fragile. Handling them was enough to simulate decades of erosion. No specimens were retrieved intact.

There must be a way to preserve them for transport. Shellac? Plaster? Bondfast?

If they are that delicate, they may be porous enough to get a thin, slow-drying bonding material to percolate through it.

fnxtr said:There must be a way to preserve them for transport. Shellac? Plaster? Bondfast?

Aha! Thank you, fnxtr! You started a train of thought that has just now pulled into the station.

MinWax makes a product called Wood Restorer which I have used for its intended use of strengthening wood that has been wet and has begun to rot. It is a fairly strong resin in a rapidly drying solvent that is brushed on, penetrates and sets in a couple hours.

You can find this stuff at the big box stores. Tall, yellow can.

Sheesh. I should have thought of that myself. Well, the insight is no less valuable because it took your help. Thanks.

In Canada we say “You’re welcome”; in the U.S. this translates roughly as “Uh-huh”. :-)

Like in the stromatolite photo above (where I just posted a similar comment), there’s little in this photo to help you understand the scale. Just how big is the “small granitic pebble” supposed to be?

Is this an in-situ photo? Is the light grey stone on the right part of the matrix surrounding the fulgurite?

The photographer says that the entire fulgurite is about 10 cm in diameter, but this photograph is only a detail. She describes the pebble as “small.” I will try to get a more quantitative answer, but I think you may assume that the field of view is at most a few centimeters wide.

Hi- the pebble is about 2 cm from top to bottom. This fulgurite was formed in a dry river bed.

The unheated soil associated with the fulgurite is a tan, sandy silt. During the lightning strike, the soil heated up to the gray color shown in this photo, forming the exterior of the fulgurite, and individual grains are cemented together with a small amount of glass.

Thank you. Now that’s the interesting stuff! So the lightning traces on the pebble are even smaller than I first thought. It makes this photo even more amazing. I think it’s just jumped to the top of my list. :D

Was this section naturally exposed, or did you have to clear away some the matrix first?

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This page contains a single entry by Matt Young published on August 10, 2009 12:00 PM.

Photography Contest Continues … was the previous entry in this blog.

Darwin → Hitler? Naw. is the next entry in this blog.

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