Vivianita
Vivianita is a mineral with formula Fe²⁺₃(PO₄)₂·8H₂O, in the Fosfatos group. This specimen comes from Cabeça de Cachorro, São Gabriel da Cachoeira, Amazonas, Brasil and joined the Terrium collection in 2025.
Description
Fully developed acicular crystal of very dark petrol-green colour. Vitreous lustre and well-defined longitudinal striations, with two small accessory crystals protruding from the sides. Without matrix. Very aesthetic.
History of this specimen
Found in 2018, put on the market (in France) in 2019–20. Popularised in Tucson 2022 alongside that year’s lot of ludlamites.
About Vivianita
A photosensitive "Necromineral" linked to processes of organic decomposition in iron-rich environments. It forms when phosphate from decomposing human or animal bodies comes into contact with water and iron. Vivianite has been found in mammoth tusks and in corpses buried for several centuries. It is photosensitive and degrades; it oxidises, changing from blue to green.
About the locality
The Cabeça do Cachorro area, in the far northwest of the state of Amazonas, has produced some of the longest and most lustrous acicular vivianites in South America. It is a remote, difficult-to-access region with intermittent artisanal mining.
Technical data
- Catalogue No.
- 0083
- Composition
- Fe²⁺₃(PO₄)₂·8H₂O
- Name
- Vivianita
- Group
- Fosfatos
- Category
- Estélites
- Mine
- Cabeça de Cachorro
- District / Municipality
- São Gabriel da Cachoeira
- Province
- Amazonas
- Country
- Brasil
- Size (cm)
- 9.5 x 0.2 x 0.2
- Weight
- 3 g
- Acquired
- 2025
- Etymology
- Named in honour of John Henry Vivian (1785–1855), British mineralogist and politician who discovered it in 1817.
- Quality
- Muy buena
- Value trend
- Estable