Andalucita Quiastolita
Andalucita is a mineral with formula Al₂SiO₅. This specimen comes from Mirabel, Cáceres, Extremadura, España.
Description
Cruciform twin of andalusite visible in polished section, with graphite inclusion forming a cross. Classic metamorphic mineral.
History of this specimen
Chiastolite, or "cross stone", is named for its characteristic cruciform twin. Historically used as an amulet by pilgrims.
About Andalucita
Variety of andalusite (orthorhombic polymorph) with carbonaceous inclusions forming a cross. Vitreous lustre, hardness 6.5–7.5 Mohs, density 3.17 g/cm³. Crystallises in low- to medium-grade metamorphic rocks.
About the locality
On the slopes of Mirabel Castle there are hornfels formed when older rocks were heated by magma. That heat caused chiastolite crystals to grow, known for their dark crosses. The site is easy to access and is well known for the many specimens in which the cross is perfectly visible.
Technical data
- Catalogue No.
- 0503
- Internal reference
- X0025
- Composition
- Al₂SiO₅
- Name
- Andalucita
- Variety
- Quiastolita
- Matrix
- Matriz metamórfica (corneanas)
- Mine
- Mirabel
- Province
- Cáceres
- Region
- Extremadura
- Country
- España
- Etymology
- Named after Andalusia; although the original locality was misattributed, the name was retained. “Chiastolite” derives from the Greek «chiastós», “marked with a cross”, for its internal pattern.
- Quality
- Buena
- Value trend
- Estable
Related specimens
- Abellaíta — España
- Abernathyita — España
- Abernathyita — España
- Abernathyita — España
- Aerenita — España
- Aerinita (fibrosa) — España
- Ágatha — Brasil
- Analcima — España