2.8" Rare Andalucite Var Chiastolite Mineral Specimen Asturias Province Boal Spain
Location: Asturias Province, Boal, Spain
Weight: 1.2 Ounces
Dimensions: 2.8 Inches Long, 0.9 Inches Wide, 0.7 Inches Thick
The item pictured is the one you will receive.
Andalucite is an important mineral in geology and mineralogy, named after the Andalusia region in southern Spain, where it was initially discovered and described. This aluminum nesosilicate is distinguished by its unique crystal structure and develops under specific metamorphic conditions. Its occurrence in Spain, especially in Andalusia, has been vital for understanding its geological setting and its function as an indicator mineral.
Andalucite is one of the three polymorphs of the mineral Al2SiO5, alongside kyanite and sillimanite. Although these minerals share the same chemical composition, they differ in crystal structure, each stable under distinct pressure and temperature conditions. Andalucite commonly occurs in medium-grade metamorphic rocks and is associated with regional metamorphism. Its presence helps geologists determine the specific pressure and temperature conditions during rock formation. The crystal system of andalucite is orthorhombic, characterized by three mutually perpendicular axes of unequal length. It typically forms prismatic crystals with a square cross-section. Andalucite’s colors can range from pink, red, and violet to brown, green, and colorless, depending on trace elements in its crystal lattice. A well-known variety, chiastolite, features a unique cross-shaped pattern of dark carbonaceous inclusions within the lighter mineral, caused by impurities incorporated along certain crystal directions during growth.
