Mystery beach rocks cause serious burns for California woman (Updated: Phosphorus)

Woman burned after picking up rocks at beach The Orange County Register.

A 43-year-old woman is undergoing surgery after two rocks that she collected at a South County beach ignited in the pocket of her shorts, officials from Orange County Fire Authority said.

The incident happened about 3:30 p.m. Saturday when the woman was standing in her kitchen after returning from an outing to Trestles Beach. She had been home for about an hour when the pocket of her cargo shorts caught fire, OCFA Capt. Marc Stone said.

The rocks, described as small, the size of a hamburger patty, smooth and orange and green in color, fell from the shorts onto the floor and continued to burn the wood floor and fill the house with smoke.

Tip: @Korbus (Jason Korbus) on Twitter

A witness said the rocks were still smoking. OCFA hazardous materials unit was consulted. The rocks have been taken to Orange County Public Heath and are undergoing testing.

Hmm. Mysterious. My first guess would have been charcoal because they may have felt just warm on the outside but still be smoldering on the inside, enough to catch clothes on fire. But that might not explain the smoke. The smell of the smoke would have been valuable – wood, sulfur-odor or chemical smell. There is not enough information in this story. Important details are missing.

Add on: The more I look at white phosphorus, the more I think it may be reasonable. It is reactive with air only 10-15 degrees above room temperature (she had it in her pocket – warmed up) and is commonly used in munitions like grenades and for smoke screens. It does cause such burns as described. Could this have been military waste or unexploded fireworks that were washed up on shore and, when dried up, exposed to air and warmed, ignited? See the ATSDR sheet here.

If anyone hears a followup to this story, let us know.

UPDATE (18-May-2012): Phosphorous substance found.

The Orange County Health Care Agency examined the two rocks, and tests revealed a “phosphorous substance” on the rocks, which now have been sent to a state laboratory for further testing, said Tricia Landquist, an agency spokeswoman.

James Earthman, a professor of chemical engineering and material science at UC Irvine, had a few possibilities: The inorganic chemical could have come from a passing ship or from nearby Camp Pendleton. And the reason for the delayed combustion could be because the rocks were still wet and didn’t ignite until they were dry — and, he noted, we don’t know what else could have been in the woman’s pockets.

Orange County Health Care Agency

The white/grey looks like common limestone pieces you would find at the beach. The green? No clue. Yellow is the phosphorus substance.

The mystery remains. I do suspect, however, that it might be solved eventually. Stay tuned.

Note: The paper spells phosphorus incorrectly. It is NOT phosphorous.


  18 comments for “Mystery beach rocks cause serious burns for California woman (Updated: Phosphorus)

  1. Massachusetts
    May 17, 2012 at 8:42 AM

    Strange, and definitely the territory of a good chemist and geologist–take your pick. I suspect it wasn’t really a rock per se. Maybe a lump of sodium that got a little wet? The coal suggestion is a good one too.

  2. Fastmover01
    May 17, 2012 at 8:57 AM

    Maybe it was some calcium carbide.

  3. Richard Cornford
    May 17, 2012 at 8:59 AM

    Isn’t a “rock” found on a beach likely to have had already plenty of exposure to water? I was wondering whether it could contain something that reacted with air that had been shielded from the air while the rock was wet and it was the drying out of the rock that let the air in and allowed a reaction to start. (Red?) Phosphorus?

  4. May 17, 2012 at 9:33 AM

    Sodium would not be found in elemental form. However white phosphorus might, not naturally but as part of something else. See my add on in the post.

  5. May 17, 2012 at 9:34 AM

    Yes, see the note above on white phosphorus (red does not seem to be very reactive). When it dries out, ignites. I’m beginning to suspect some military waste was washed up on shore, perhaps. Dangerous stuff. But they should be able to figure this out from what sample remained.

  6. Massachusetts
    May 17, 2012 at 9:51 AM

    Good point about sodium. I was thinking maybe some demented chemistry grad student dumped a lump on the beach as a prank, but that would be highly unlikely and strange of course, though exploding rocks are rather unusual for starters I guess. I do like the white phosphorous hypothesis. An interesting story all around; I hope we learn soon what the tests reveal.

  7. May 17, 2012 at 9:52 AM

    For what it’s worth, MRE heaters use water as a catalyst for an exothermic chemical reaction that provides enough heat to warm an MRE dinner. The proper term appears to be “flameless ration heater.”

  8. Richard Cornford
    May 17, 2012 at 11:53 AM

    I mentioned red phosphorus because among the little evidence presented is the description “orange and green in color” so I think any explanation needs to be proposing something that addresses that descripting. I noted that the Wikipedia page on phosphorus state that “white phosphorus almost always contain some red phosphorus and therefore appear yellow” and that “Even under water, white phosphorus is slowly converted to the more stable red phosphorus allotrope”, and a transition from yellow to red should give a material that could easily be described as “orange”, while still containing enough white phosphorus to start reacting at low temperature (and then heat the red phosphorus up to a temperature where it would also react with oxygen from the air). If we assume that this thing has been washed ashore then part of it may have started off as fairly pure white phosphorus and then spent sufficient time under water to now be well on its way to being all red, but still have enough white left (Under the surface?) to be self-igniting.

    Then there is the “green” described in the “rock”. As I recall, copper compounds are often green, and can be used to colour flames (e.g. in fireworks). I suppose that could also be the mangled and corroded remains of a copper casing. So a firework/military flare that has spent some time in the sea seems like a good explanation to me.

  9. LREKing
    May 17, 2012 at 4:52 PM

    Maybe something from the Japanese tsunami?

  10. Massachusetts
    May 17, 2012 at 10:08 PM

    I’d love to suggest the energy tech of the Innsbrook Fish People but I’d probably get banned…

  11. May 17, 2012 at 10:51 PM

    It just goes to show the dangers of smoking rocks.

  12. May 18, 2012 at 11:25 AM

    I’d be shocked if this isn’t WP. I love the speculation that it could be a passing ship, or some other source …. or, you know, the nearby military base.

    In case you’re wondering this stuff is, it’s used for flares, yes. But it is also used as an incendiary round against human targets, most infamously in recent years during the Battle of Fallujah where WP and MK77 rounds were fired into the city along with high explosive rounds, as a tactic called “shake and bake.” While not illegal, the use of incendiary rounds against human targets brought world-wide controversy (the stuff burns down to the bone, is very difficult to remove or extinguish which sounds a lot like the case of the woman who was injured in this case, and should not be contacted by attending medical personnel), especially after Defense Department initial denials of the tactic (saying that WP had only been used as flares) before admitting to their use, some months later.

    Here’s a basic roundup on it, but there is a lot more information.

  13. May 18, 2012 at 11:31 AM

    I would be shocked too. WP is WELL KNOWN by all military artillery personal. I just mentioned it to my husband (former Marine artillery) and he knew exactly what I meant and how it reacts. The location of the military base, the use of the ocean for exercises, it all seems to make the most coherent story.

  14. Z
    May 18, 2012 at 3:59 PM
  15. Chew
    May 18, 2012 at 9:24 PM
  16. May 18, 2012 at 9:32 PM

    That’s the same link I added earlier today on the update.

  17. Chew
    May 18, 2012 at 10:21 PM


  18. Wretched1
    May 21, 2012 at 5:33 AM

    I was recently watching an older show about the paranormal and unexplained on Netflix. This one episode dealt with Spontaneous Human Combustion and had a case almost exactly the same as this in Newfoundland. An expert from both sides of the issue was sent to study a woman that had survived “suddenly bursting into flames”. She had been at the beach and on the way home her upper legs and pants burst into flames. The only things in her pockets were stones/shells she had accumulated at the beach. Both experts decided it was these stones/shells and not SHC.

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