John Ruskin, "Etude en couleurs d'un bloc de quartz affecté par l'érosion", vers 1875, John Ruskin, circa 1875

John ruskin, "color study of a block of quartz affected by erosion", circa 1875. Graphite, watercolor and gouache on wove paper. Oxford, ashmolean museum, university of oxford. Presented by john ruskin to the ruskin drawing school (university of oxford), 1875. Photographed in paris in 2021 at the musée d'orsay during the exhibition "the origins of the world. The invention of nature in the 19th century". Date: circa 1875.