Rhodonite at Akatore

That wonderful pink coloured mineral of manganese found South of Akatore Creek. This mineral has long been sort after by rockhounds and others for carving, jewelry making and of course as cabinet specimens.

The Akatore collecting site is through private farmland and permission from the land owner is required.

The Otago Rock and Mineral Club for many years held the mining rights to this resource. Many fine specimens have been taken from the site and early reports indicate that large quant’s were removed in 44 gallon drums by helicopter in the 70’s.

Rodonite from Akatore is a beautiful pink colour interlaced with fingers of the mineral pyrolusite – the black oxidized form of manganese – showing wonderful patterns when cut and polished. Some areas within the manganese band have rich manganese nodules of a lighter pink colour – but extremely hard.

The NZ Crown Minerals Commodity report on manganese reports ‘about100t of manganese ore was mined South of Taieri Mouth (Hector, 1892). The mineralisation occurs within a 3.7 m-thick band in a brown argillite/chert sequence in Haast Schist. The band contains massive manganese oxide mineralisation as pods, up to 15 cm thick, and more commonly as small pockets and veins Manganese minerals include pyrolusite, manganite and ramsdellite (Coombs, in Reed 1959). Hector (1892) gave analyses between 17.0% and 58.1% manganese.

Manganese mineralisation is also found a few kilometres to the south, on the coast, south of Akatore Creek (Read and Reay, 1971). Felsic metatuff within Haast Schist contains metachert–carbonate lenses up to 3 m thick, with pink coloured pods of manganese mineralisation up to a meter thick. Associated metavolcanic rocks developed from basic tuffs, breccias and flows. Rhodochrosite and akatoreite are the main manganese minerals, along with rhodonite, spessartine, pyroxmangite and tinzenite (Read and Reay, 1971). Secondary wad, psilomelane, pyrolusite and todorokite fill veinlets and blacken outcrops.

For the full report click here : NZ Crown Minerals

Once collected the rhodonite must be protected from sunlight as the colour will begin to fade to a brown colour and eventually turn black.It has aslo been found that over heating (by cutting or polishing) the pink colour of the rhodonite can be turned brown.