Cookin’ on a Hot Rock (Hillbilly Science 101)
Now listen here — when ya heat up a rock over a campfire to cook on, how much heat that sucker can spit out depends on three things: how much heat it can hold (that’s its specific heat capacity), how big it is, and how hot ya get it.
But don’t go heatin’ up just any ol’ rock, ‘cause some’ll pop like a shotgun if there’s water trapped inside. Ya only wanna use dry, solid ones that ain’t full of holes — like them dense riverbed rocks that been sittin’ outta water for a good long while.
What Makes a Rock Hold Heat
Specific Heat Capacity:
That’s just fancy talk for how much energy it takes to warm up a chunk of somethin’. Rocks don’t hang on to heat near as good as water does, but some do better’n others:
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Granite: ‘bout 790 J/kg°C
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Basalt: ‘bout 860 J/kg°C
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Quartz: ‘bout 730 J/kg°C
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Water: a whoopin’ 4182 J/kg°C
Mass:
The bigger the rock, the more heat it’s gonna hang on to. Little rocks cool off quicker’n a squirrel on a hot griddle.
Temperature Change:
If ya heat a rock to, say, 300°C and let it cool down to 100°C, it’ll throw off more heat than if ya only let it drop to 200°C. The hotter it gets, the more cookin’ power ya got.
How to Fry an Egg on a Rock (If Ya Wanted To… Bless Your Heart)
Cookin’ an egg on a rock works ‘cause of conduction — that’s when heat scoots from the hot rock into the egg.
Here’s how ya do it:
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Pick the Right Rock: Don’t grab them porous, water-soaked river rocks — they’ll go kaboom when the steam builds up. Go for a flat, dark, solid one like shale or sandstone.
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Heat It Up: Stick that rock close to the campfire. Let it sit till it’s hotter’n a black skillet in July, but don’t bury it in the coals or it might crack.
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Clean It Off: Pull it out with tongs or a stick and brush off the dirt ‘n ashes.
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Add a Dab of Grease: Smear on a bit of oil or butter so the egg don’t weld itself to the rock.
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Cook the Egg: Crack ‘er open right on the rock. It’ll sizzle and pop a bit, cookin’ up a rustic but dang fine breakfast.
Why Ya Can’t Just Cook an Egg on the Sidewalk
Folks like to brag ‘bout fryin’ eggs on the sidewalk in summer, but that’s mostly hogwash.
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Ain’t Hot Enough: Even on a scorcher, pavement might hit 140–160°F, but ya need at least 158°F (70°C) to really cook an egg.
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Loses Heat Too Quick: The second ya slap a cool egg down, that surface chills off faster than a beer in a creek.
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Cooks Uneven: Ya end up with a half-snotty, half-burnt mess.
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Kinda Gross: Dirt, bird poop, and gum ain’t exactly gourmet. Rangers been tellin’ folks to quit doin’ it ‘cause it just makes a sticky ol’ mess.
So there ya have it — cookin’ on rocks ain’t just for cavemen or campers with too much time on their hands. Pick yourself a good rock, heat ‘er up proper, and you’ll have breakfast fit for a campfire king.
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