Last updateFri, 22 Mar 2019 1pm

Obsidian specialists plan first archaeological dig in Selva Negra

Only three years ago, archaeologists had no idea that Ahuisculco’s Selva Negra Forest probably houses Mexico’s biggest obsidian deposit.

pg7aIn 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.


After a long drive along a lonely dirt road, we hiked for a kilometer, depending entirely upon GPS to guide us to one particular mine, hidden among dozens of others. When my GPS said we had arrived at a spot I had identified as “Wow” (because the archaeologists and geologists had found it so exciting), Esparza and his colleagues began a careful inspection of the area. When they finally stopped for a break, I asked Esparza to explain what we were doing there.


“We’re starting this project to take a close look at this particular site, which we are calling El Encinar (The Oak Grove),” he told me, “When Chris Lloyd showed us this spot in March 2016, I noticed that all the stages can be seen for the production of bifacial blades made of ‘meca’ obsidian, which is obsidian of two colors, in this case red or brown plus black. Bifacial blades are those that have been painstakingly chipped on both sides: fancy blades, perhaps for ceremonial use. But what is most important about this site is the fact that it is completely intact, undisturbed since pre-Hispanic man worked here. So we can see the raw material they used, still inside the open trenches from which they extracted it.”

Esparza continued: “Then, we have visible evidence of just about every stage of the chain of production, something you don’t often see next to a pre-Hispanic obsidian mine. It was more common for them to shape preforms and take them off to the city for further work. Why they decided to do everything right here may be related to the fact that meca obsidian is relatively scarce, but as time goes by, we may learn more about that.”

Esparza suspects the mines and workshops at Selva Negra may be over 2,000 years old, but this requires “verification.”  The apparent lack of constructions, tombs or ceramic objects may make this difficult, but the archaeologist hopes technology will help determine a date.

Proyecto Arqueológico El Encinar is getting financial help from Jalisco’s Secretariat of Culture and “assistance of all kinds” from the Selva Negra Foundation.

“We plan to launch this project in June and hope to to make lots of important discoveries,” Esparza concluded.

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