Comment on xkcd #3075: Anachronym Challenge

zabadoh@ani.social ⁨1⁩ ⁨week⁩ ago

Sidewalk chalk isn’t made of chalk anymore?

TIL: It’s made of calcium sulfate, i.e. gypsum, the same stuff that goes into drywall, as opposed to calcium carbonate, i.e. rock chalk.

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