[Rockhounds] fulgurites

[Kreigh Tomaszewski]

I've had five close (between 5 and 68 ft) experiences with lightning. 
One of them was a strike to a live tree. The steam produced from 
heating the sap in the struck branch caused it to explode. I suspect 
this is the fate of most possible fulgerites from lightning strikes.

I suspect the proper conditions are a thin wet conductive surface, 
relatively dry sand under it, and a conductive water table somewhat 
deeper.

The Boston Science Museum has two of the world's largest Van De Graf 
generators and they put on daily shows of lightning. They also have a 
great exhibit of fulgurites. I wonder if they could be talked into 
doing research into making fulgurites (and sell the results in their 
gift shop)?

Kreigh





On Tuesday, Sep 16, 2008, at 13:17 America/Detroit, pmodreski at aol.com 
wrote:

> It's been interesting to read everyone's comments about fulgurites; 
> I've just been catching up on my Rockhounds email, after being very 
> tied up with the Denver Show, a preceding mineralogical conference in 
> Golden, and having been away visiting my family in New Hampshire the 
> week before that.
>
> You bet, lechatlierite is for sure a mineraloid.? The name is 
> "traditionally" mentioned in mineralogy books, but it definitely is 
> not found in sources such as the Glossary of Mineral Species, which 
> only list bona fide approved mineral species.? Lechatlierite occurs in 
> fulgurites, and has also been recognized in some impact-deformed 
> rocks, subject to intense pressure and temperature.? A somewhat 
> analogous term is maskelynite, which is glassy (melted) plagioclase 
> feldspar from shock impact, known from some meteorites and (according 
> to Mindat.org) from at least one terrestrial impact structure.? I 
> don't know if there is another such name, for melted potassium 
> feldspar.
>
> I've been interested to read people's comments about searching for, 
> and finding, fulgurites.? I've always considered that they are quite 
> uncommon and very hard to find, and, like meteorites, I think almost 
> all have been found by accident, not by anyone's systematic 
> searching.? (That statement used to be true for meteorites but no 
> longer really as, in view of the large number that have been found in 
> Antarctica, as well as in the Sahara.)
>
> Something that I have puzzled over, is, what proportion of lightning 
> strikes, actually produce fulgurites?? I'm not sure that anyone really 
> knows this; there are thousands of lightning strikes every day, 
> worldwide; but I'm not sure if anyone knows if it does or doesn't take 
> special conditions of soil/sand type, moisture, etc., to make a 
> fulgurite.? It's likely that in many instances, the lightning 
> discharge may travel first through other material (such as trees and 
> tree roots) down into the ground before it begins to melt sand and 
> form a fulgurite, so many fulgurite may be "hidden" underground, and 
> would not be found or noticed unless someone excavated in the right 
> spot where there had been a lightning strike.
>
> Likewise a puzzle--and we have talked about this before on this 
> List--is how common it is for lightning strikes on rock outcrops, to 
> produce a fulgurite.? One always reads "anecdotally" that there exist 
> melted patches on rocks near mountain summits where lightning has 
> struck, but I am still not sure that I have ever actually seen a 
> picture of such a thing (much less see one in person), or read any 
> definitive documentation that ANYWAY has ever really seen such a 
> thing.? My suspicious is that most lightning strikes on mountains, if 
> they do not hit trees, go to the crevices between rocks where moist 
> soil is likely to be more conductive, and that any melted rock that 
> forms, may be in the form of rock fragments contained in the soil down 
> beside or in cracks within bedrock.? The closest I've seen is one 
> specimen, in Kreigh's collection, of a small piece of granite "from 
> the Colorado mountains" partially melted by lightning; but I don't 
> believe the source of his specimen had provid!
>  ed any specific information of how/what/where this actually 
> occurred.? A few years ago, some collectors brought a large fulgurite 
> specimen to the Denver Museum of Nature & Science, from a lightning 
> strike on a ridge high above Boulder Canyon, in Colorado (the Museum 
> subsequently acquired the specimen); it was from a lightning strike I 
> believe at a tree stump, and the fulgurite was excavated by digging 
> out the crevices between and beneath the rocks around it; I don't 
> think any actual melted rock was observed on exposed rock surfaces.
>
> Pete Modreski
>
>
>
> -----Original Message-----
> From: kugeln at peoplepc.com
> To: Rockhounds at drizzle.com: A mailing list for rock and gem collectors 
> <rockhounds at lists.drizzle.com>
> Sent: Mon, 15 Sep 2008 6:17 pm
> Subject: Re: [Rockhounds] fulgurites
>
>
> Fulgurites are one of the very few mineraloids that are a true glass. 
> The glass is known as LeChatelierite. Pete Modreski, correct me if I'm 
> wrong.?
> ?
> ----- Original Message ----- From: "ROBERT A SANTEE" 
> <timeman123 at optonline.net>?
> To: <rockhounds at lists.drizzle.com>?
> Sent: Monday, September 15, 2008 6:19 AM?
> Subject: [Rockhounds] fulgurites?
> ?
>> Hi can anybody give me any info how I can find fulgurites I just 
>> started > to collect them and I thought it would be great to look for 
>> them.I live in > New Jersey and I do not no if that would be a good 
>> area to collect them > any info would be great thanks bob.?
>> ?
>
>
>
>
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