Natrojarosite
3 in the gallery
Natrojarosite is a hydrated sodium-iron sulfate mineral. It forms as a secondary product in oxidized sulfide-rich environments and typically occurs as earthy to tabular, often iridescent crystals or crusts with a yellow to orange-brown color. The mineral commonly exhibits a dull to pearly lustre and can occur in aggregates or acicular habits, reflecting its sulfated composition.
- Formula
- NaFe3(SO4)2(OH)6
- Rarity
- Common
- Stability
- Stable
- Collector interest
- Moderate Interest
- Classification notes
- Sulfates; hydrous iron sulfate mineral (IMA group; natrojarosite subgroup)
Key characteristics
- Crystal system
- trigonal
- Mohs hardness
- 2.5–3.5
- Specific gravity
- 3.18
- Luster
- vitreous, resinous, dull
- Transparency
- transparent, translucent, opaque
- Color
- yellow, brown, orange
- Streak
- yellow
- Cleavage
- distinct
- Fracture
- uneven, subconchoidal
- Crystal habit
- rhombohedral, tabular, granular, massive, druzy
Where Natrojarosite is found
Top localities
- El Entredicho Mine1 specimen
- Milpillas Mine1 specimen
About Natrojarosite
Specimens of natrojarosite have been reported from several notable localities, with Greece, Mexico, Spain, and the United States standing out for their exposed oxidized zones where sulfidic bodies weather and form secondary minerals. Collectors prize well-formed crystals and crusts that display vivid color and crisp termination, especially when associated with other iron sulfates or secondary minerals in the same oxidized zone. Its occurrence alongside related sulfates provides diagnostic context for mineral enthusiasts studying alteration sequences and mineral paragenesis in hydrothermal or supergene environments.