Quartz-veined ophicarbonate, consisting of ferroan dolomite-ankerite-calcite-talc, and rare goethite.

(Grapes et al, 1999) describes some mineralised lodes on and near the Richmond Hill Mine, which is listed as a separate entry, and then mineralisation for the surrounding Parapara River/Richmond Hill Porphyry. This is a small gneissic granodiorite pluton. The mineralisation between the mine and porphyry are quite different.

The gersdorffite occurrence is north of the mine, as a 21 metre wide, iron stained talc carbonate with quartz veins. The contact between the porphyry, and Waingaro Schist is marked with 50-100 mm band of magnesite-quartz, while the main part of the body contains antigorite-talc-magnesite, with rare peridotite, amphibolite, and chlorite schist.

The gersdorffite occurs as tiny homogeneous euhedral microscopic crystals, of a pyritohedral habit. It is found with pyrrhotite, chromite, tremolite, and calcite. Chromite has been partly replaced with chromian magnetite and magnetite. Chromite occurs as clusters of angular grains. Calcite as boundaries to quartz, and larger areas enclosing quartz grains.

The pyrrhotite is partly replaced by pyrite, in turn replaced by violarite. The pyrite and violarite, and more rarely pyrrhotite-pyrite occurs as intergrowths in veins, along cleavage planes in tremolite, talc, and carbonates, and within interstitial areas.

Mindat map approximate, as the source merely shows a map of the porphyry in relation to the Richmond Hill Mine.

Other Regions, Features and Areas containing this locality

References