TERRIUM — A mineralogy cabinet


Ópalo Menilito

Ópalo is a mineral with formula SiO₂·nH₂O, in the Mineraloides (Óxidos) group. This specimen comes from Embalse de Camarillas, Agramón, Hellín, Albacete, Castilla-La Mancha, España and joined the Terrium collection in 2026.

Ópalo Menilito from Embalse de Camarillas, Agramón, Hellín, Albacete, Castilla-La Mancha, España — Terrium

Description

Large, white, peanut-shaped menilite with a very smooth, matte surface.

About Ópalo

Menilite is a variety of common opal, without the play of colour of precious opal. It formed on the floors of ancient lakes from deposits of biogenic silica produced by diatoms (microscopic algae with minute siliceous skeletons). It characteristically develops rounded forms that, by chance and pareidolia, sometimes suggest human or animal figures. For this reason they have long been called "little idols" and have been used since prehistory in rituals and as amulets.

About the locality

The Camarillas Reservoir is noted for its menilite opals with a matte texture and colours from light grey to whitish. Their genesis is linked to silica-rich lacustrine deposits in a sedimentary setting.

Technical data

Catalogue No.
0399
Composition
SiO₂·nH₂O
Name
Ópalo
Variety
Menilito
Group
Mineraloides (Óxidos)
Category
Meritum Persé
Matrix
Caliza
Mine
Embalse de Camarillas
District / Municipality
Agramón, Hellín
Province
Albacete
Region
Castilla-La Mancha
Country
España
Acquired
2026
Etymology
Menilite is a toponymic derivative of Ménilmontant, a district of Paris that serves as the type locality.
Quality
Muy buena
Value trend
Estable

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