The Hatfield vein occurs in a rock of igneous origin, known as the Williamsburg granodiorite. It is exposed at the west edge of the valley, about 200 feet from Federal Highway 5, at the northern limit of the settlement called West Hatfield. The workings are full of water, and the very thorough mining activities carried on by mineral collectors and by Smith College and Amherst classes have reduced the waste pile to negligible proportions. Early collections and records reveal that the vein is essentially like those farther south. At Hatfield, West Farms and Loudville the fractures do not parallel the systems in the Triassic sediments and lavas. A galena-bearing vein outcrops near the Whately-Williamsburg town line at the north end of the Northampton reservoir. Leyden argillite forms the walls of a fault fissure. Barite is absent from this vein, but fine quartz, pyrite and chalcopyrite coat the walls. Coarse comb quartz encrusts the older minerals, together with breccia fragments and cubes of galena. The vein is remote from the valley and differs in mineralogy and texture from those within the valley. Other deposits like it have been found in the nearby hills. [Illustration: Fig. 23. _Geologic map of the region in the vicinity of the lead veins near Leverett._] 1. Only barite in these veins 2. Best mineral locality 3. Best place to see fault 4. Slickensides and tension cracks show direction of movement on fracture making opening for vein 5. Best place to see quartz replacing barite along crush zones in vein The Leverett lead vein is the most interesting of the group because it is so well exposed that the nature of the vein system is admirably displayed. The deposit lies in a series of overlapping, nearly vertical fault fissures in gneiss. Slickensides and tension cracks on the walls of the veins indicate that the movement was nearly horizontal from northeast to southwest. Wherever a fracture begins to narrow and close up, another begins to widen and become conspicuous a few feet to the northwest of it. Several different fissures appear along the length of the mineral zone. The same minerals are present as are found in the Loudville, West Farms and Hatfield veins, but barite is more abundant and quartz less so. Numerous cavities lined with crystals indicate that the vein formed close to the earth’s surface. Apparently the minerals entered fractures situated near the front of a range that bordered the basin in Triassic time. A fault zone so located would lack the great thickness of rock that once lay over the gneiss and would be free from any appreciable overburden of outwash within the Triassic basins. _The Dinosaur Tracks Near Holyoke_