Climbing

The list of a day on rock. Near the end sits le sac à magnésie, which English calls a « chalk bag », and the two names disagree about what is inside it. The powder is magnesium carbonate. Chalk is calcium carbonate, the soft white rock of a cliff or a schoolroom, and there is none of it in the bag: English named the stuff after a mineral it is not, while French named the chemistry. The French word repays a minute, because a place is hiding in it. La magnésie is Latin magnesia, from Greek Magnēsia, a district of Thessaly whose stones had a reputation. One of them pulled iron towards it, the lapis Magnesius, and that is where English got « magnet ». Another gave its name to the metal magnesium, and the white powder is a salt of that metal. So a climber chalking up at the foot of a route is holding one Greek place name in both hands, and it is the English word for it, not the French one, that points at the wrong rock.