Location:

Nenthead area, North Pennine Orefield

Extensive lead, zinc and fluorite mineralization occurs as flats and veins cutting Carboniferous Limestone. The area lies within the highest temperature zone of mineralization above an apical portion of the Weardale granite.

Major Minerals:

Sphalerite, galena, pyrite, marcasite, chalcopyrite

Minor Minerals:

Gersdorffite, glaucodot, pyrrhotite

Trace Minerals:

Include bismuthinite, argentopentlandite, light rare earth fluorocarbonates, monazite, xenotime

Textures:

Tabular monoclinic pyrrhotite is intergrown with pyrite, chalcopyrite and minor sphalerite. Pyrrhotite is altered to pyrite, marcasite and magnetite and has glaucodot and gersdorffite overgrowths. Chalcopyrite carries bismuthinite, pyrrhotite and rare argentopentlandite inclusions. Sphalerite shows extensive colour banding some of which is related to compositional variations. Monazite is intergrown with xenotime within quartz, and LREE fluorocarbonates are common as lath-shaped crystals in quartz.

References:

Ixer et al., 1979a; Vaughan and Ixer, 1980; Ixer, 1986; Brown et al., 1987