Amatista
Cuarzo is a mineral with formula SiO₂, in the Silicatos [Tectosilicatos (Grupo Cuarzo)] group. This specimen comes from Iraí, Alto Uruguai, Rio Grande do Sul, Brasil and joined the Terrium collection in 2025.
Description
Flower bouquet. Two well-differentiated amethyst rosettes, very pale lilac in colour, with good transparency and lustre. The aggregates crown an elongated, narrow matrix, resembling a stem wrapped in paper. Under the loupe, the matrix shows a matt, scattered green speckling, most probably celadonite.
About Cuarzo
It belongs to the suite of Iraí amethyst that develop the so-called "flower" habit: open, radial or fan-like aggregates that grow outwards from the cavity rather than lining a closed void as in the classic geodes of southern Brazil. These forms are associated with open cavities and brief crystallisation pulses. Although this growth style existed previously, it was not recognised or marketed systematically until the mid-2000s, when it began to appear regularly at international shows. Since then it has become one of the most distinctive and recognisable expressions of amethyst.
About the locality
Iraí is a mining locality in the far north of Rio Grande do Sul, noted worldwide for producing amethyst with atypical habits (flowers, rosettes, inverted sceptres) extracted from cavities in the basalts of the Serra Geral Formation.
Technical data
- Catalogue No.
- 0303
- Composition
- SiO₂
- Name
- Cuarzo
- Variety
- Amatista
- Group
- Silicatos [Tectosilicatos (Grupo Cuarzo)]
- Category
- Estélites
- Matrix
- Basáltica
- Associations
- manganocalcita, celadonita
- Mine
- Iraí
- District / Municipality
- Alto Uruguai
- Province
- Rio Grande do Sul
- Country
- Brasil
- Size (cm)
- 7 x 4 x 3
- Weight
- 62 g
- Acquired
- 2025
- Etymology
- From the Greek "amethystos" ("not intoxicated"), from the ancient belief that it protected against drunkenness.
- Quality
- Top
- Value trend
- Estable
Related specimens
- Ágatha — Brasil
- Cianita — Brasil
- Cianita (Negra) — Brasil
- Cianita (Negra (Taramita)) — Brasil
- Cristobalita — Estados Unidos
- Cuarzo — Madagascar
- Cuarzo (Ahumado) — Namibia
- Amatista — Kazajistán