Only three years ago, archaeologists had no idea that Ahuisculco’s Selva Negra Forest probably houses Mexico’s biggest obsidian deposit.
In 2009 this woodland was declared a Protected Area under the patronage of the Selva Negra Foundation, financed by the Guadalajara rock group Maná. It was hoped that this wilderness would serve as an animal corridor between two of Jalisco’s biggest wildlife sanctuaries: the Primavera Forest next to Guadalajara and the Sierra de Quila, located to the southwest.
No one was thinking about obsidian or archaeology when Selva Negra was created. Yes, Ahuisculco was listed as a place where archaeologist Phil Weigand had noted the presence of obsidian, but no study had been made of the extent of that deposit until Canadian geologist Chris Lloyd came upon the scene in 2015.
I had shown Lloyd a few spherulites – naturally formed stone balls – from a quarry outside Selva Negr,a and when he went to visit the site, he identified it as a volcanic dome from which vast amounts of liquid obsidian had oozed less than 10,000 years ago. Lloyd began to map this and other flows, discovering that the Ahuisculco deposit covers over 5,000 hectares. Its full extent is still not known, but Lloyd thinks it may turn out to be Mexico’s biggest.
Most of this obsidian is of good quality and ancient mines abound in the Ahuisculco Forest. These are shallow depressions or trenches from which chunks of raw obsidian were removed and then shaped into “cores” from which blades could be extracted.
One of these mines, deep inside the Protected Area, caught the attention of archaeologist Rodrigo Esparza of the Archaeological Study Center of the Colegio de Michoacán. Last week Esparza – who has a special interest in obsidian – and his collaborator Camilo Mireles invited me on a reconnaissance of the area, which at this time of the year is covered by a deep layer of oak leaves.