Andradite (Demantoid variety)
Image: <bdi><a href="https://www.wikidata.org/wiki/Q56247090" class="extiw" title="d:Q56247090"><span title="mineral collector and dealer">Robert M. Lavinsky</span></a></bdi> (CC BY-SA 3.0)
Mineral NameAndradite (Demantoid variety)
Chemical FormulaCa3Fe2(SiO4)3
Mohs Hardness6.5
Crystal Systemcubic
Lusteradamantine
Streak Colorwhite
Cleavagenone
Fractureconchoidal to uneven
Specific Gravity3.85
Colorsgreen, yellowish-green
Transparencytransparent
Type LocalityFranscia Mine, Campo Franscia, Lanterna Valley, Malenco Valley, Sondrio Province, Lombardy, Italy
Mineral GroupSilicates (Garnet Group)
Usesjewelry, collector
Associated Mineralschlorite, serpentine, magnetite, diopside
Rarityrare
Description
This specimen features numerous vibrant green, well-formed demantoid garnet crystals, ranging from small to a few millimeters, scattered across a greyish-green matrix, likely serpentinite.
Geological Context
Demantoid garnets typically form in serpentinized ultramafic rocks or skarns, often in association with chromite, resulting from regional or contact metamorphism.
