Calle Circón

The name comes from a stone. Zircon is a zirconium silicate that crystallises in honey, brown, greenish or transparent tones, and when it reaches the size and purity of a gem it glows with a fire that made it pass for centuries as an imitation diamond. The street belongs to a corner of Delicias, next to Legazpi, where the street names are organised around elements, metals and minerals. A few steps away are Calle Berilo, Calle Circonita and Calle Cobre, so that a walk here amounts to a tour through a sample case of mineral matter. Zircon also holds a record that is hard to imagine. The oldest known crystals on Earth are grains of zircon found in the Jack Hills of Western Australia, dated to about 4,374 million years, almost as old as the planet itself. Their lattice traps traces of uranium that work like a clock, which is why geologists use them to date the ground beneath our feet. Anyone reading the plaque on Calle Circón walks, without knowing it, on the name of the oldest terrestrial material ever dated.