Melanterite
2 in the gallery
Melanterite is a hydrous iron(II) sulfate mineral with the formula FeSO4·7H2O. It forms as small, transparent to pale crystals and masses that are typically colorless to pale blue-green, often with a vitreous to subsilky luster. Common habit includes acicular habit and radiating aggregates, and it readily dehydrates in air to grayish, powdery material, which is a key aspect for collectors to note when preserving specimens.
- Formula
- Fe2+(H2O)6SO4 · H2O
- Rarity
- Common
- Stability
- Moderately Stable
- Collector interest
- Moderate Interest
- Classification notes
- Sulfates: hydrated iron(II) sulfate minerals (Sulfates with water of hydration)
Where Melanterite is found
Top localities
- Southwest Mine1 specimen
- Mona mine1 specimen
About Melanterite
Notable localities include mining districts and old sulfate-bearing deposits in Peru, the United Kingdom, and the United States, where Melanterite occurs in oxidized zones and as alteration products of iron sulfide minerals. Specimens from these areas are valued for their relative abundance, the delicate crystal forms, and their association with sulfates in historic or classic mineral occurrences. Collectors favor well-formed crystals and well-documented provenance, as these factors enhance display and study, while the mineral’s hydration state makes it a useful indicator of collection conditions and storage practices.