Eritrina Punta de lanza
Eritrina is a mineral with formula Co₃(AsO₄)₂·8H₂O, in the Arseniatos group. This specimen comes from Agoudal, Bou Azzer, Ouarzazate, Drâa-Tafilalet, Marruecos and joined the Terrium collection in 1970.
Description
Triangular micaceous fuchsia crystals. A central 7 mm spearhead-shaped crystal stands out.
History of this specimen
When I had this piece in hand I knew at once it could not be kämmererite, or clinochlore, as the seller claimed. The crystallisation was completely different. After researching, I confirmed it was an erythrite from Agoudal. With it I learned that erythrite can also crystallise as shown here: in spearheads or perfect rhombs. It is also an exceptional piece: the contrast with the black-metallic matrix sets off intact crystals, free of chips or fractures, and a principal crystal of unusual size that is a pleasure to study under the loupe. It came from an earlier collection from the 1970s and, given the quality, it is very likely to have belonged to the stock of the old dealer Gary Hansen. A delightful piece and a fortunate purchase.
About Eritrina
It is the fuchsia vivianite, a hydrated cobalt arsenate. Its colour ranges from pale pink to intense fuchsia depending on the cobalt concentration. It forms by alteration of arsenides in the oxidised zones of Co–Ni–As deposits. At Agoudal it develops flat, pointed crystals with silky lustre and deep wine colour, often mistaken for roselite or anorthoroselite.
About the locality
In the Bou Azzer district, and especially at Agoudal, erythrites occur in cavities within altered Co–Ni arsenides, with scorodite and quartz. The mine is noted for producing specimens with exceptionally saturated colour and a compact matrix, denser than in other parts of the district.
Technical data
- Catalogue No.
- 0213
- Composition
- Co₃(AsO₄)₂·8H₂O
- Name
- Eritrina
- Variety
- Punta de lanza
- Group
- Arseniatos
- Category
- Cavella
- Matrix
- Matriz arseniatada
- Mine
- Agoudal
- District / Municipality
- Bou Azzer
- Province
- Ouarzazate
- Region
- Drâa-Tafilalet
- Country
- Marruecos
- Size (cm)
- 6 x 4 x 3
- Acquired
- 1970
- Etymology
- From the Greek "erythros", 'red', for its characteristic colour.
- Quality
- Top
- Value trend
- Al alza
Related specimens
- Abernathyita — España
- Abernathyita — España
- Abernathyita — España
- Acantita (Paramórfica tras Argentita) — Marruecos
- Adamita — México
- Adamita — México
- Adamita (Cuprífera) — Grecia
- Adamita — México