We present the results of the chemical analysis of obsidian artifacts from the Villa JMC-1 Labranza site, in the middle basin of the Cautin River, central valleys of south-central Chile, dated approximately 1000 years BP (early Pottery period). We argue that the interpretation of the obsidian chemical groups in archaeological sites in the south-central area of Chile has been biased by sampling and limitations of the analytical techniques used. This implied a low visibility of eastern chemical groups in the south-central Chilean sector, which was interpreted as evidence of the limiting character of the Andes mountain range, in dissonance with other evidence. The enlargement of the sample and the use of nondestructive techniques on the total collection of the site has allowed us to demonstrate that three of the five obsidian artifacts come from two chemical groups from the eastern mountain range. Some technological aspects of the properties of raw materials and their superficial modifications suggest the exploitation and selective supply of chromatic varieties that possibly required access to primary sources. Finally, the spatial distribution of the chemical group CP-LL1 is greater than previously thought. We identify its first occurrence in Chile.