Akrochordite is a rare hydrated manganese arsenate mineral, part of the adelite–descloizite group. It is scientifically notable for its unusual chemistry and its occurrence in oxidized arsenic-rich environments.
🌍 Origins and Naming
- Name Origin: From Greek akrochordon (“wart”), referring to its typical wart-like crystal aggregates.
- First Described: 1955, from Långban, Sweden (a classic locality for rare arsenates).
- Type Locality: Långban mine, Värmland, Sweden.
🔬 Chemical and Structural Properties
- Formula: Mn₅(AsO₄)₂(OH)₄·4H₂O
- Mineral Group: Arsenates (adelite–descloizite group)
- Crystal System: Monoclinic
- Color: Brownish-red, reddish-orange, sometimes pinkish
- Habit: Small wart-like aggregates, crusts, or granular masses
- Hardness: ~3.5–4 on Mohs scale
- Specific Gravity: ~3.6
- Luster: Vitreous to dull
- Streak: Pale brown
⚙️ Geological Occurrence
- Forms in oxidized zones of manganese-arsenic deposits.
- Associated Minerals: Allactite, hausmannite, jacobsite, and other rare arsenates.
- Localities:
- Långban, Sweden (type locality, famous for rare arsenates)
- Other manganese-rich deposits in Austria, Germany, and the USA (Franklin, New Jersey).
📖 Scientific and Collector Significance
- Petrology: Important for understanding arsenate mineral paragenesis in manganese-rich environments.
- Collectors: Rare and usually found as small aggregates, but valued for its unusual reddish coloration and rarity.
- Economic Note: No commercial use due to rarity, but academically significant.
⚠️ Safety Considerations
Contains arsenic, so specimens should be handled with care—avoid inhaling dust or ingesting particles, and wash hands after handling.
✨ Conclusion
Akrochordite is a rare manganese arsenate mineral, first described in Sweden, recognized for its wart-like reddish aggregates. While not economically important, it is prized by collectors and mineralogists for its rarity and contribution to understanding arsenate mineralogy.
In short: Akrochordite = Mn arsenate, reddish wart-like aggregates, rare, first found at Långban, Sweden.
