This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
I never understood why getting a lump of coal instead of presents should be considered a threat. I'm a coal miner's daughter (yes, really. Okay, so he was an engineer at a coal mine, but it counts). The best thing my dad ever gave me, aside from the pony and the playhouse and the Breyer Horse stable that I adored for nearly a decade, was a lump of coal. I'd been after him about it for a long time. "Daddy, please bring me a lump of coal from the mine! Pleasepleaseplease I'll be good!"
If I'd had a better grasp on reverse psychology, or my dad a somewhat better-developed sense of irony, I might have ended up with one earlier. Regardless, one day, he arrived home with an enormous black chunk of ancient swamp, and I cherished it until we lost it in a move.
I'll never forget visiting Black Mesa once. I was very young, probably no older than 7 or 8, and we drove through a black canyon gashed by machines in the thick seams of coal that made up the mesa. I don't know what I'd expected, maybe a tunnel, like I'd seen in various pictures of mining operations. I stared, slack-jawed and thrilled beyond containment, at those shiny black walls towering above me. And then there was the fire, and the truck with a mounted hose spraying an enormous rooster tail of water on it. Fires sometimes started in the seams, my dad told my astonished young self. They'd burn for years. You couldn't really fight them so much as contain their spread. They sometimes could manage it with water; sometimes, they'd have to bury the blaze and hope it would burn itself out safely under the soil.
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I'd never considered that there might be any such thing as a fire that burned year after year, that no number of fire trucks and firefighters could defeat. And when I got my hands on that hard lump of coal, and realized this tough shiny stuff was what did the burning, I was amazed. It didn't really sink in then, but it did later. These were rocks. Rocks that burn.
What fool decided this was a disincentive to naughtiness?
But kids seemed to take that threat seriously. They'd rather have the shiny toys than a shiny lump of coal. I don't think they were future geologists, or there would have been a considerable uptick in the naughty quotient whenever that threat was made.
Angry parent: "If you don't stop doing X bad thing, all Santa's giving you this Christmas is a lump of coal!"
Future geologist: "Awesome! Two, please!"
My original lump has been replaced by a smaller but no less cherished chunk purchased from a wonderful little rock shop down in Cottonwood, AZ. And that wee delight has been joined by several bits picked up during rambles along Coal Creek (aptly named), which was my first opportunity to pick up coal in the wild. I love this stuff.
But I've saved the best for last. It hasn't much to do with coal, except it's on Coal Creek, and it's just the most awesome orange waterfall I've ever had the pleasure of getting up-close and personal with:
And if you're very naughty, I may venture back out there and collect a lump or two just for you.
A version of this post originally appeared on Rosetta Stones in 2013.