The image is a vintage diagram depicting a geological formation. It shows a cross-section of a 'vein of greenstone in clay slate'. The slate is represented by a large, irregular shape filled with closely spaced, parallel lines, suggesting its layered structure. A vertical, oblong shape in a muted green color represents the greenstone vein, cutting through the slate. The diagram is set against a pale yellow background and appears to be a lithograph or similar print. Below the diagram, in bold black text, is the title 'VEIN of GREENSTONE in CLAY SLATE.'. Beneath that, centered, is the number '13.' and to the right 'Charlestown, Mass.'. The image has a slightly aged appearance with some discoloration and wear around the edges.