Analcima
Analcima is a mineral with formula NaAlSi₂O₆·H₂O, in the Silicatos (Tectosilicatos) group. This specimen comes from Minas de Gilico, Calasparra, Murcia, Región de Murcia, España.
Description
Cubic to trapezohedral crystals with colour varying from white to green, and pink zones caused by the matrix and associated minerals. The piece shows a broad cavity (fissure) with well-defined crystals and bright terminations visible to the naked eye.
History of this specimen
This is a rich paragenesis with evident fluorapatite and calcite, responsible for the lustre and localised fluorescence under UV light, as well as the green and pink tones in the matrix. I value the piece for its play of colours and crystalline texture.
About Analcima
Analcime is a tectosilicate zeolite with a cubic structure, composed of sodium, aluminium, silicon and water. It crystallises typically in volcanic environments with moderate hydrothermal activity, and occurs as cubic or rhombododecahedral crystals. It was first described in 1797 and is known for its reaction to ultraviolet light, especially in well-developed aggregates. Although usually an accessory mineral, in some deposits it forms well-developed crystals sought by collectors.
About the locality
Minas de Gilico, at los Baños de Gilico between Calasparra and Cehegín, lie in an ophitic volcanic setting with cavities lined with zeolites and secondary minerals. They have been worked since Roman times. Although not industrially active, they yield analcime locally regarded for its quality.
Technical data
- Catalogue No.
- 0021
- Composition
- NaAlSi₂O₆·H₂O
- Name
- Analcima
- Group
- Silicatos (Tectosilicatos)
- Category
- Cavella
- Associations
- fluorapatito calcita
- Mine
- Minas de Gilico
- District / Municipality
- Calasparra
- Province
- Murcia
- Region
- Región de Murcia
- Country
- España
- Size (cm)
- 6 x 5 x 3
- Weight
- 92.9 g
- Etymology
- From the Greek "ἀναλκιμος" ("analkimos"), meaning "weak", in reference to its low electrostatic charge when rubbed.
- Quality
- Buena
- Value trend
- Estable
Related specimens
- Abellaíta — España
- Abernathyita — España
- Abernathyita — España
- Abernathyita — España
- Aerenita — España
- Aerinita (fibrosa) — España
- Afghanita — Afganistán
- Afghanita — Afganistán