Ópalo Hialita
Ópalo is a mineral with formula SiO₂·nH₂O, in the Mineraloides (Óxidos) group. This specimen comes from Valeč, Karlovy Vary, Bohemia, República Checa and joined the Terrium collection in 2025.
Description
Completely transparent globular aggregates of hyalite opal with vitreous lustre lining a cavity in volcanic matrix. No fluorescence. Typical for this locality.
About Ópalo
Hyalite is a rare variety of opal lacking play of colour, noted for its vitreous aspect and formation in hydrothermal settings. It forms at low temperatures when silica-rich solutions percolate through volcanic cavities. As the solutions cool, silica precipitates in thin layers, producing glassy, globular coatings.
About the locality
Valeč is noted for producing very transparent, lustrous hyalites, uncommon at other localities where they are often more milky or show marked fluorescence.
Technical data
- Catalogue No.
- 0149
- Composition
- SiO₂·nH₂O
- Name
- Ópalo
- Variety
- Hialita
- Group
- Mineraloides (Óxidos)
- Category
- Cresta Montis
- Matrix
- Matriz volcánica
- District / Municipality
- Valeč
- Province
- Karlovy Vary
- Region
- Bohemia
- Country
- República Checa
- Size (cm)
- 4.5 x 4.5 x 5
- Weight
- 113 g
- Acquired
- 2025
- Etymology
- From Sanskrit «úpala», via Greek «opállios», in the sense of precious stone. The variety hyalite comes from the Greek «hyalos», “glass”, for its vitreous appearance.
- Quality
- Buena
- Value trend
- Estable
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- Granate (Hesonita (Grosularia)) — República Checa
- Limonita (Botroidal) — España
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- Metaorbernita — República Checa