These samples have occurred in surface collections of Archaic period cruciforms in northern Chihuahua. The nodules are typical of Tertiary marekenites in the Basin and Range Province.
None display the green cast often associated with peralkaline glasses.
Most are smoky gray to brown. Elemental concentrations for Lago Barreal, Chihuahua source standards collected by LeTourneau. Copyright 2000 M. Steven Shackley . All rights reserved. 18 April 2000 Back to the SW obsidian source page.