The
Morning Star mine is one of numerous historically mined gold-quartz lodes in the
Preservation Inlet goldfield of southwest Fiordland. The mine is hosted in Early
Ordovician metasedimentary rocks that are composed predominantly of psammitic
and pelitic lithologies. These rocks still contain their primary depositional
features and are characterised by upper greenschist facies metamorphic
grade.

The
Morning Star mine lies on the eastern limb of a gently south plunging anticline.
A bedding parallel fault-vein and an associated network of minor quartz veins
hosts mineralisation. The main fault-vein structure strikes N-NW, dips steeply
(~60) W, has a strike length of ~350 m, a vertical extent of ~170 m and is up
to 2 m in thickness. The internal structure of the fault-vein consists of
laminated quartz, massive and fibrous quartz, and silicified
breccias/cataclasites. Gold is typically coarse grained (~1 - 2 mm) and
associated with pyrite, arsenopyrite, chalcopyrite, tetrahedrite and galena. The
geometry of the Morning Star mine is similar in form to that of a saddle reef.
Gold-quartz lodes in the Preservation Inlet goldfield are comparable in geometry
and host rock to their offset equivalents in the Golden Blocks field of NW
Nelson.