3.2" Rare Andalucite Var Chiastolite Mineral Specimen Asturias Province Boal Spain
Location: Asturias Province, Boal, Spain
Weight: 13.2 Ounces
Dimensions: 3.2 Inches Long, 2.4 Inches Wide, 2.3 Inches Thick
The item pictured is the one you will receive.
Andalucite, a significant mineral in the geological and mineralogical fields, derives its name from Andalusia, a region in southern Spain where it was first identified and described. This aluminum nesosilicate mineral is characterized by its distinctive crystal structure and its formation under specific metamorphic conditions. Its presence in Spain, particularly in the Andalusian region, has been crucial for understanding its geological context and its role as an indicator mineral.
Andalucite stands out as one of the three Al2SiO5 polymorphs, joined by kyanite and sillimanite. While they share an identical chemical makeup, their crystal structures diverge, each thriving under distinct pressure and temperature environments. This mineral usually emerges in medium-grade metamorphic rocks, often tied to sweeping regional metamorphism. Its presence boldly signals the precise pressure and temperature conditions during rock formation, offering geologists a powerful key to unlock the mysteries of metamorphic transformation.
Andalucite crystallizes in an orthorhombic system, characterized by three unequal, mutually perpendicular axes. It typically forms prismatic crystals, often with a square-shaped cross-section. The mineral’s color ranges widely, including shades of pink, red, violet, brown, green, and sometimes clear, influenced by trace elements in its structure. A distinctive type of andalucite, known as chiastolite, features a unique cross-shaped pattern created by dark carbon-rich inclusions. This pattern occurs due to impurities concentrating along certain crystallographic directions during crystal growth.
