Listwanite at Atlin
The carbonate alteration of ultramafic rocks to listwanite, rusty-red quartz - talc - carbonate - Cr-muscovite (mariposite/fuchsite) assemblages, is well known for its association with lode-gold mineralization, making it an attractive prospect for exploration. Listwanite alteration is structurally controlled along pre-existing fault and fracture networks. These served as high permeability pathways for percolation of CO2-rich fluid. A mineralogically zoned halo of carbonate alteration extends for tens of metres into wallrock adjacent to the controlling fracture.
Distribution of Carbonate alteration at Atlin (click on map to enlarge)