Pudost Stone: The Rock Near Gatchina That Built Saint Petersburg

Picture a stone you can cut with a knife, like cheese. You press the blade in, and it slides through and leaves a clean, flat face. That stone lay in the ground near the village of Pudost, by the town of Gatchina, outside Saint Petersburg.

While it sat underground, soaked with water, workers could saw it and carve it. Once it was lifted out and dried, it set. It grew hard, as hard as marble, and the blade no longer went in. So the workers cut their blocks early, while the stone was still soft. Only afterwards did it turn into finished rock, something you could chisel and polish but never slice again.

Geologists call it calcareous tufa, a kind of travertine. It was laid down on the bed of an ancient lake by water rich in minerals. It is close kin to the Roman travertine that the Colosseum is built from.

In the late eighteenth century, the architect of the Gatchina Palace noticed it. He came from a country where real travertine was ordinary, so he knew what he was looking at. Pudost stone faced the palace vestibule. It also clad a wall of the Priory Palace.

Then the capital took notice. Andrey Voronikhin chose it for the colonnade of Kazan Cathedral, the great curved arms of columns that open onto Nevsky Avenue. There are ninety-six columns, Corinthian, with leafy carved tops. The stone was several times cheaper than the Italian import, and it looked nearly as good and held up nearly as well.

But the supply was small. It was not a seam running for kilometres. It was a modest lens of rock in the valley of a single river. By the end of the nineteenth century, stone good enough for big blocks was almost gone. What was left went for rubble and lime.

Go to Pudost today and you won't find quarries. You'll find a mill on the Izhora river, a federal monument, with a small museum pavilion beside it.

And here's what stays with me. Those columns have stood for more than two centuries in Petersburg rain and snow. The quarries are closed for good. The stone came out of the ground once, and it is still working in its third century. It didn't end up in a few modest buildings and vanish without a trace.

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