Fulgurite: Petrified Lightning

Perhaps fulgurites are not so much gemstones, but they still are very interesting for the rock and mineral collectors among us.

Jewelry is made with it as well, though it is fairly rare and usually limited to pendants. This is because fulgurites are too fragile for use in rings and looks plain in small sizes.

What is Fulgurite?Fulgurite

Fulgurite (or fulgarite) is named after the Latin word ‘fulgur’ which means thunderbolt. The reason for this is that fulgurite is created when lightning strikes sand.

The temperature of lightning, air-temperatures over 30,000 °C have been measured, is far higher than the sand melting point of 1800 °C.

The silica, which makes up the sand, fuses together at this extreme heat. Creating the so-called lightning glass or lightning sand.

The glass that is formed in this way is called lechatelierite, which also forms when meteorites hit sand or silica-rich rocks, such as the gemstone moldavite.

The color of the fulgurite depends on the type of sand struck by lightning. While the size of the fulgurite depends on the penetration of the lightning in the ground.

The size usually ranges from just a few centimeters to several decimeters. However far larger fulgurites have been found, most notably one in the state of Florida in the USA that was 4.9 meters long.

Often fulgurites that are formed by an intense bolt of lightning have a branch like structure. As lightning follows the path of least resistance when it strikes the ground.

Most fulgurites are made in sand, however they can also be formed when silica-rich rocks are struck by lightning. Usually these are smaller in size, because lightning has more difficulty with penetrating the harder rock.

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Where Can I Find Fulgurite?

Fulgurite can be found anywhere in the world, provided there is sand or silica-rich rock present. They are relatively rare, though this might be because most people don’t recognize fulgurite when they see it. The best places to look for it would be in deserts, beaches or mountain tops. Especially after the passing of a particularly violent thunderstorm.

Mountain tops are probably the best place to look as they can be hit dozens of times in just a single storm. Make sure the rock there has a high silica content or you might just find small burnt spots instead of a natural treasure. Find out what type of rock is most often found there and look up the composition, this could save you a “wasted” trip.

Be careful when you think you spotted a fulgurite, trying to break it free by grabbing the top part could just leave you with a small fragment. You might have to excavate the fulgurite. Excavating sand fulgurites sounds fairly easy as you can just sweep the sand away right?

In reality however, you have to treat it almost like an archaeological dig site. Use plastic tools and brushes and bring a friend to support the top part in case you find a large specimen.

Rock fulgurites can be even harder to extract if they are still embedded in the surrounding rock. These will require metal tools to extract and a single missed strike from a geological hammer or another tool can shatter them.

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Fulgurite Care

Fulgurites are almost always part of a mineral collection and require no special care as such. Just be gentle with it as they are prone to breaking.

If you bought a piece of fulgurite that you intend to wear regularly you should be very careful. Bumping into things and dropping it could chip or shatter it. Chipping is not a big problem as it doesn’t really look out of place on fulgurite. Shattering of course poses more of a problem.

Cleaning should be done with lukewarm water and at most a bit of soap. Make sure it dries completely before storing it. There is no need to clean it regularly as it doesn’t have a surface that smudges easily, unlike most gemstones.

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Fulgurite Buying GuideFulgurite

We would advise against buying rings or other jewelry and only buy a fulgurite pendant. There are two reasons for this: The first reason is that fulgurite is very fragile and you should keep it away from harm. A pendant or necklace is the best choice for this.

The second reason is that fulgurite can hardly be polished and looks fairly uninteresting in small sizes, making rings or earrings a bad choice.

Buying a fulgurite for your mineral collection should be fairly easy, just ask your local dealers or find a dealer online. Just do a background check to make sure you are dealing with someone reputable.

Finding fulgurite jewelry is probably going to be a lot harder. Amazon.com for example only carries two fulgurite pendants on a total of over 2.5 million pieces of jewelry. From what we can tell both pendants were made by a single company. We could not find any other suppliers, if you know of any please leave a comment at the bottom of this page.

Fulgurites for sale are often sold per gram and not per carat like gemstones. Most dealers sell it for $1 to $2.5 per gram for regular fulgurites. The rarer white fulgurite or fulgurites that were made by a heavily dispersed lightning bolt can often sell for far more than that. You can expect to pay around $50-$100 for a good sized fulgurite that will make a nice addition to almost all collections.

Artificial fulgurite exists and is quite easy to make. Usually it is made by running a current through slightly moist sand. Some of these artificial fulgurites start disintegrating within months. My advice is to stay away from them and get a natural one. Read the disclosure when you buy fulgurite or ask the dealer about it. It is unclear how widespread the sale of artificial fulgurite is, but it doesn’t hurt to be careful.

Fulgurite can look quite beautiful even if it is not as suitable for jewelry as other gemstones. Once you realize however that you are looking at physical evidence of the raw power of nature, it makes it worth owning regardless.

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Comments

  1. Bill Larsson says:

    Great article, from experience I can tell you that it can take quite a while to get an idea of where to find fulgurites in the desert. A nice way to make things easier on yourself is to take along some metal rods the next time you go hunting. Stick the metal rods in the ground (somewhere easy to find again, so not too remote) and head home.

    Once a storm has passed and you are in the area pay a visit to the metal rods you left behind. Chances are lightning has struck the rods themselves or the vicinity. If lightning struck the rods the fulgurite will be easy to find, right beneath the metal rod. Otherwise you’ve got some hunting to do, but it narrows your search down a lot.

    Success is not guaranteed, but it sure increases your chances!

    • GemstonesAdvisor says:

      Thanks for the advice, quite useful if you are planning to make multiple trips to the same area. Just keep in mind that leaving metal rods lying around will be frowned upon in some places. So make sure you’re not violating any rules or get permission beforehand.

      GemstonesAdvisor

    • Anonymous says:

      I really like this idea and with all this white sand at the beach and sea shore, I should have no trouble creating the perfect conditions. I suspect copper rods would be best.

  2. Sciencemall.com has a variety of fulgurite jewelry if anyone would be interested. Very cool article by the way!

  3. I have a very LARGE piece of fulgurite (approx. 16″x6″ & 10lb) from the California Sierra Nevada foothills,(gold country) that I would like to sell, but have no idea where,how, how to price it or anything ! Can you/somebody help me w/this ? It has a large center “glass” section w/many small “runners” coming off the main section. It is a beautiful blackish purple.

  4. Ralph Gonzales says:

    I have a fulgurite collection . Fulgurite site is in Palm Springs. Specimens have more branches than any fulgurite you will see on any site. Send me an Email and ill send you pics.

  5. Hello,

    I have rock fulgurite that was confirmed by a geologist at UND Nels F. I have pictures as well I could send but I have a large amount of it. Mostly black mineral type looking glassy, I am not overly familiar with it but am learning as I go.

    Please let me know if you can where is the best place to start selling it.

    Thank you,

    • GemstonesAdvisor says:

      Hi,

      Your best option would be to contact a local rockhounding club and see if they are interested. Even if they don’t want to buy any they might know someone who is interested.

      Gemstones Advisor

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