Sunday, June 12, 2011

Egg Geology

Many of us have seen old lava flows and volcanoes - but did you know that you can make a yolk volcano? I didn't until I discovered it by accident (... and despite my best efforts I have not been able to replicate it).

How to find it
You will know one of your hard boiled eggs harbors a yolk volcano if you find the following yolk strings in the water:

The source of the flow
Follow the strings until you find the source, you guessed it, a hole in the side of the egg where the shell broke and the yolk slowly oozed out, boiling along the way.

Peeling away the outer layers shows the structure of the volcano where the yolk (magma) broke to the surface of the white (crust).

Splitting open the yolk you can see the stress fractures in the direction of maximal ooz.

But what pushed it out?
The little air pocket in the egg expanded as the water boiled leaving a nice airy room (which filled with water once the egg cooled.


  1. Ah, but was it delicious?

  2. This has got to be one of the very few times when Yoni has made two posts in a row, without another brother in between.
    I know Eli will share the specific stats.

  3. @AJ Ha!
    @Anonymous I'm not rerunning stats now, but as of our 5th year stats roundup, Yoni's posted in a row 8 times (now at least 9 times).

    Now, a general response:
    1) Try using older eggs, where the air pocket will be more pronounced.
    2) It looks like that was a big crack that didn't break the membrane -- have you tried that? Also, I often accidentally crack eggs (hairline) if I don't put them in the pot gently.

  4. @AJ, yes! very delicious!
    @Eli, worth a try