Description
Olmiite – Wessels Mine, Kalahari Manganese Field (South Africa)
Size: ± 5.7 cm
Visual description
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This specimen shows a clustered growth of pale honey-yellow to beige crystals, forming a rounded, drusy to botryoidal-looking surface.
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The crystals appear short-prismatic to blocky, tightly packed, with a soft vitreous to slightly resinous lustre.
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There is a clear contrast between the light-coloured olmiite crystals and the dark manganese-rich matrix beneath, which anchors the piece visually and highlights the crystal growth.
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Minor surface staining and earthy coatings are typical for Wessels material and add to its natural, mine-fresh character.
Geological context
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Olmiite is a rare calcium–manganese borate mineral, first described in 2006.
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The Wessels Mine is the type locality for olmiite and one of the world’s most important sources.
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It forms in hydrothermal manganese-rich environments, often associated with other unusual borates and manganese minerals from the Kalahari Manganese Field.
Key identifying features
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Pale yellow to beige colour
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Compact crystal clusters rather than isolated crystals
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Association with dark manganese matrix
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Locality: Wessels Mine (a major value and credibility factor)
Collector significance
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Olmiite is genuinely rare, not just “uncommon”
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Highly sought after by:
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Systematic mineral collectors
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Locality collectors
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Kalahari manganese specialists
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Even modest-sized specimens are desirable because of the mineral’s short history and limited global occurrence
Condition & appeal
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At 5.7 cm, this is a solid cabinet to large thumbnail specimen
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Good contrast and complete crystal coverage make it visually appealing
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Not museum-grade perfection, but very respectable collector quality
Indicative value (retail estimate)
For a specimen of this size and quality from Wessels Mine:
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