Verdigris is what time deposits on copper. The word comes from the Old French vert-de-Grèce — green of Greece — named for the patinated bronze of the ancient world. It is not one compound: verdigris is copper acetate, copper sulphate, or copper chloride, depending entirely on what the copper has been exposed to. Salt air produces one shade. Acid rain another. The breath of a city, another still. The surface records every atmosphere it has passed through.

The low afternoon light does something particular to verdigris: the warm amber sun and the blue-green mineral cancel and amplify each other simultaneously, producing a third colour that belongs to neither. You see it on old copper roofs at this hour — the patina seems to glow from within, as if the mineral is generating its own light rather than merely reflecting it.

What you are looking at is a section of copper architectural cladding — the kind found on cathedral cornices, baroque domes, or old civic buildings — weathered over decades. The exposed copper showing between the patches is not damage. It is simply younger verdigris, still forming. The fine white traces at the edges of each patch are calcium deposits: mineral runoff from the stone above, marking the exact boundary where copper chemistry ends and something else begins. Given time and five o'clock air, everything copper turns.