Bismuthinite-bearing quartz veins from the Alston Block of the North Pennine Orefield are all close to, or above, the Rookhope and Tynehead cupolas of the buried Weardale Granite. They are uniform in composition and paragenesis and are earlier than the main fluorite-baryte-galena-sphalerite mineralization of the orefield. Rhythmical crystallization of quartz, chalcopyrite and minor pyrite is followed by fluorite-quartz-chalcopyrite-minor sphalerite-altered pyrrhotite mineralization. Early tin-bearing (up to 0.29 wt.% Sn) chalcopyrite encloses trace amounts of bismuthinite (Bi₂S₃), synchysite (CaREE(CO₃)F₂), argentopentlandite (Ag(FeNi)₈S₈) (close to being stoichiometric), pyrrhotite, cubanite and cosalite (Pb₂Bi₂S₅), while early pyrite carries monoclinic pyrrhotite (close to Fe₇S₈) and tungsten-bearing cassiterite (up to 1.03 wt.% WO₃). Bismuthinite is macroscopically visible and is associated with native bismuth and small, fine-grained, spherical aggregates that qualitative analysis suggests may be cosalite crystals. Synchysite and more rarely monazite, xenotime and adularia are intergrown with bismuthinite. These mineralogical data form part of the basis for an increasing awareness of the contribution of the Weardale Granite to the early phases of mineralization in the Alston Block.