A good small representative piece of white to yellow microcrystalline Hinsdalite coating joints in the rock veinstone and forming pseudomorphs after small Pyromorphite crystals.   Frongoch Mine was noted in the nineteenth century for large brown Pyromorphite crystals, but also renewed interest in the site was shown in the 1980's-1990's when a large range of rare Pb-Cu-Zn secondary minerals were found.  It was only quite recently that Hinsdalite and Corkite were noted to be present.