The image is a vintage illustration of a rock formation containing a large crystal. The rock is irregularly shaped, with a rough, textured exterior. Within the rock, a prominent crystal structure is visible, composed of numerous slender, needle-like crystals radiating outwards. The crystals are densely packed, creating a feathery or fibrous appearance. The illustration is rendered in a detailed, hand-drawn style, with fine lines and shading used to depict the textures of the rock and crystals. The background is a pale yellow, and there is text at the bottom of the image indicating the date (April 1, 1809) and publisher (J. Sowby, London). A number '31/2' is written in the top right corner.