Olmiite is found exclusively in the NChwaning II Mine, Kuruman, North Cape Province, Kalahari manganese field of South Africa.
To the west of Kuruman in the Northern Cape province, South Africa lies the massive manganese deposits of the Kalahari manganese field which covers at least 1100 square kilometres. These deposits have become world famous for the large reserves of ores and for the wide range of specimens identified and classified. There are 140 different species of minerals classified from this locale.
Olmiite is an interesting and rare mineral and was only described and named in 2006. Most crystals now called Olmiite were described as Poldervaartite. The name Olmiite has become accepted for the majority of the known material. Olmiite is named for Filippo Olmi, an Italian mineralogist.
The difference between Poldervaartite and Olmiite is not visually identifiable. Manganese dominates in Olmiite and Calcium dominates in Poldervaartite. Most of the earlier 1980's and 1990's finds at the Wessels Mine are Poldervaartites and the later finds from the N'Chwaning II Mine are Olmiite (Some of the 2001 pocket did test as Poldervaartite.) Both forms makes for some very unique and interesting specimens and they are always in high demand by collectors.
Item # OLM11109761
Olmiite Crystals on matrix N'Chwaning II Mine
OLMIITE 16858 N'Chwaning II Mine, Kalahari Manganese Field, South Africa
Fairly new mineral! Blocky crystals to 4 mm, some have sharp terminations, some are etched, rich on top of matrix. Good deep red UV SW fluorescence. This specimen is from Mineral Zone-12/28/2008 and D.H. Garske 8/2010.
This piece weighs 43g (1.5oz) and measures 2.7 x 1.4 x 0.7” (69 x 37 x 20mm)