The rocks along the lower Fortymile River (EA071) are Paleozoic amphibolite-facies gneiss, schist, quartzite, marble, and amphibolite (Foster, 1976). Bedrock in the immediate vicinity of the Weston scheelite occurrence is schist that has been intruded by several small granitic bodies of Tertiary or Mesozoic age (Saunders, 1957; Foster, 1976).The lower Fortymile River adjacent to the Weston occurrence has been mined for placer gold, and scheelite is abundant in sluice-box concentrates. In 1957, a narrow vein of scheelite-bearing quartz, 1 to 2 feet thick, was exposed at the Weston placer mine about 300 feet downstream of the Taylor Highway Bridge on the south side of the Fortymile River. Two similar quartz veins were found on the north side of the river. These veins are parallel to the veins on the south side of the river, and they are about 1 inch thick. Samples from a 1-inch-thick quartz vein containing scheelite were examined under ultraviolet light. One appeared to contain 5 to 10 percent WO3, and the other is somewhat lower in grade. Two other samples were assayed, but no gold, silver or tungsten were present (Saunders, 1957).