Nodules of obsidian from primary sources located to the east in the Warner Mountains are locally available in secondary alluvial deposits in the Alturas Basin. Out of 15 geochemically characterized geologic specimens collected from surficial deposits near the Alturas Airport, 11 were found to originate from the Buck Mountain source, one correlated with the Harris Flat source, and five samples (the Alturas Airport Unknown A source) failed to match any sources in our laboratory source reference database. Freshly-cleaved surfaces of flakes from this unknown source are dark gray in color, exhibit a matte surface texture and slightly earthy surface luster, and are relatively free from inclusions. Thin flakes are completely opaque. Although this source is probably better described as a glassy rhyolite than an obsidian, the toolstone quality of this lithic material is very good. Similar materials have been proven to be excellent candidates for trace element characterization studies (Newman and Nielsen 1987).

Provenance studies of artifacts from a site located at the Alturas Airport indicate that this source material was being locally used, at least in relatively small quantities.

Obsidian Hydration: Due to the crystalline nature of the glass, obsidian hydration rims cannot be measured for artifacts correlated with this source.