Stones have always slept beneath the open sky brings together a series of photographic works made in dialogue with the litho-mineralogical collections of the Museo di Storia Naturale La Specola in Florence. The project developed through the study of minerals, rocks and other specimens preserved in the museum collection, which became the starting point for a series of images made using historical photographic processes. The photographs explore the encounter between two surfaces capable of recording traces: the surface of the stone and the photosensitive surface of the photographic print. Moving between geological, photographic and astronomical forms of time, the work considers the apparent stillness of both stone and image. What appears fixed is instead the result of processes unfolding across radically different scales: pressure, erosion, sedimentation and mineral transformation on one side; exposure, chemical reaction and the gradual alteration of the printed matter on the other. The project brings together these different temporalities without attempting to reconcile them. Photography becomes a way of observing matter as it changes, while the museum collection provides a context in which objects formed over immense periods of time are brought into relation with the much shorter duration of human observation. The book reflects on photography not simply as a means of representing matter, but as another material surface in which time, light and transformation leave their traces.