$300Median
8Sold (12 mo)
$400Last sale
Sturmanite specimens for sale
6 for sale · $500–$2,000 USD
26 in the gallery
Sturmanite is a hydrated calcium iron sulfate borate mineral that forms as complex, often prismatic to tabular crystals. It typically exhibits a pale to yellow-brown color with a vitreous to resinous luster and may occur as aggregates or crusts in deeply weathered pyrite-rich environments. The mineral’s structure incorporates sulfate groups with borate components, reflecting its intricate chemical makeup and layered crystal framework. Notable localities are dominated by South Africa, where oxidized zones and hydrothermal settings have yielded well-formed, sometimes sizable specimens that attract careful collection and study.
- Formula
- Ca6Fe3+2(SO4)2.5[B(OH)4](OH)12 · 25H2O
- Rarity
- Rare
- Stability
- Moderately Stable
- Collector interest
- High Interest
- Classification notes
- Sulfate; ettringite group
Key characteristics
- Crystal system
- trigonal
- Mohs hardness
- 2.5–3
- Specific gravity
- 1.8–1.9
- Luster
- vitreous, silky
- Transparency
- transparent, translucent
- Color
- yellow, orange, brown
- Streak
- white
- Cleavage
- none
- Fracture
- uneven
- Crystal habit
- prismatic, acicular, fibrous, radiating, massive
Buy Sturmanite specimens
View all 6Where Sturmanite is found
Top localities
- N'Chwaning II Mine11 specimens
- N'Chwaning Mines7 specimens
- Aggeneys1 specimen
- N'Chwaning III Mine1 specimen
- Wessels Mine1 specimen
About Sturmanite
Collectors prize sturmanite for its unusual composition and the rarity of high-quality crystals. The combination of sulfate and borate groups, along with its hydrated nature, often results in distinctive forms and textures that stand out in a cabinet of minerals. While not the most common accessory in mineral collections, superb crystals from premier South African pockets are sought after for their rarity, complexity, and the insight they offer into secondary mineralization processes.
