Tynebottom Mine, North Pennine Orefield, Britain

A large sphalerite flat has replaced Carboniferous Limestone close to a quartz dolerite sill as part of the Mississippi Valley style mineralization of the North Pennine orefield. Associated with this flat are minor quantities of a late stage assemblage within a quartz and calcite gangue that share mineralogical similarities with the five metal association.

Major Minerals:

Chloanthite, rammelsbergite, argentopyrite, chalcopyrite, pyrargyrite, acanthite

Minor Minerals:

Safflorite, violarite, pyrite, marcasite, sphalerite, stephanite

Trace Minerals:

Include lollingite, sternbergite, cubanite


Chloanthite is successively overgrown by twinned and zoned rammelsbergite, euhedral safflorite and lollingite. Chalcopyrite is intergrown with cubanite and silver minerals. It encloses thin lamellae of an unnamed AgFeS2, mineral and is compositionally zoned. Argentopyrite forms asteriform aggregates and is sector twinned. It alters to a mixture of a lath-shaped AgFe8S11 mineral, acanthite, pyrite and marcasite. Much of the acanthite is photosensitive.


Ixer and Stanley, 1987