Analcima
Analcima is a mineral with formula NaAlSi₂O₆·H₂O, in the Silicatos (Tectosilicatos) group. This specimen comes from The Horseshoe Dam Area, Maricopa County, Arizona, Estados Unidos and joined the Terrium collection in 2025.
Description
White to pink crystals on volcanic matrix, with cavities showing additional crystallisations with UV response. US zeolite with cubic structure. Excellent under a loupe.
History of this specimen
A dense matrix and crystallisations visible to the naked eye; UV response is localised in the fissures, highlighting zones with higher crystal concentration. From a volcanic area of Arizona, United States.
About Analcima
Analcime is a tectosilicate zeolite with a cubic structure, composed of sodium, aluminium, silicon and water. It typically crystallises in volcanic environments with moderate hydrothermal activity, and occurs as cubic or rhombododecahedral forms. It was first described in 1797 and is known for its UV response, especially in well-developed aggregates. Although commonly an accessory mineral, in some localities it forms well-formed crystals prized by collectors.
About the locality
The Horseshoe Dam area, Maricopa County, Arizona, lies in an altered volcanic setting characterised by basalts and tuffs with vesicular zones. Minerals such as analcime form in these cavities, often with natrolite, calcite and iron oxides. Although not a classic locality nor a major producer, it has yielded small analcime specimens with good definition, partial fluorescence and distinctive aesthetics. It is a representative example of zeolites from the south-western United States.
Technical data
- Catalogue No.
- 0023
- Composition
- NaAlSi₂O₆·H₂O
- Name
- Analcima
- Group
- Silicatos (Tectosilicatos)
- Category
- Cavella
- Mine
- The Horseshoe Dam Area
- District / Municipality
- Maricopa County
- Province
- Arizona
- Country
- Estados Unidos
- Size (cm)
- 3.7 x 3.2 x 2.2
- Weight
- 26.6 g
- Acquired
- 2025
- Etymology
- In 1797 René Just Haüy named analcime from the Greek 'an-alkimos' ('without strength'), referring to its weak triboelectric response when rubbed, compared with species such as tourmaline.
- Quality
- Buena
- Value trend
- Estable