This biface thinning flake is from the Tosawihi opalite quarry near Battle Mountain in northern Nevada.  The flake was struck to thin and flatten a bifacial Tosawihi ‘white knife’.  It likely dates to the Late Holocene period.

 

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This flake was struck in thinning and flattening a biface at the Tosawihi stone quarry.  The flake was struck parallel to a flake struck from the opposite edge, demonstrating a ‘full-face’ thinning technique—a more controlled variant of the ‘overshot’ (or outrepassé) technique, which removes part of the edge opposite the platform.  The platform is lipped and the flake was probably struck with a soft hammer, such as antler.

See the annotations for technological details about this stone tool.

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Tosawihi is one of the largest Native American stone quarries in the Great Basin.  Clovis points have been found made from Tosawihi opalite, dating to ca. 11,000-13,000 BP, and the stone was used for tools into the historic period.  Tosawihi stone is called ‘opalite’ and was formed by geothermal processes.  The same geothermal processes concentrated gold in the local geological deposits, and much of the quarry area has been exploited since the 1980s by the Hollister gold mine.  Some 115,000 ounces of gold have been extracted from the Hollister mine.

Tosawihi opalite is predominately white in colour, and ‘Tosawihi’ translates to ‘white knife’ in the Western Shoshone language.  The Western Shoshone band who traditionally controlled the quarry are called the Tosawihi Shoshone.  The Western Shoshone mourn the mining activities that have destroyed much of the quarry.  Tosawihi knives were extensively traded throughout the northern Great Basin, with artefacts from the quarry said to have been found in Canada and New Mexico.  In the historic period, Tosawihi knives were preferred for making the body incisions for the sacred Ghost Dance.  Tosawihi Shoshone today sometimes carry pieces of Tosawihi opalite for its spiritual meanings and properties.

To extract the stone, Native Americans dug pits through the soil to the thick opalite bedrock underneath.  Once exposed, the stone was bashed with heavy hammerstones to separate natural cracks.  Cracks were also separated by driving in bone wedges.  Chunks detached using these methods were reduced near the pits into early stage bifaces.  This was skilfully accomplished by a mixture of hard-hammer percussion using disk-shaped and spherical hammerstones, and soft-hammer percussion using heavy elk antler billets.  Primary thinning was accomplished at the quarry locations, and these blanks were carried away to the living sites a few kilometres away.  There they were heat-treated to enhance the stone’s flakability.  Heat-treatment of Tosawihi stone caused it to become glossy compared to the unheated material, and much easier to knap, but unlike many heat-treated materials, the white colour stayed the same.  After heat-treatment, many of the bifaces were secondarily thinned by soft-hammer percussion to create the final blank.  Final blanks were oval or bi-pointed in shape, and measured ca. 100-150 mm long and 60-80 mm wide on average, and ca. 10 mm thick.  These late-stage bifaces were exported from the quarry where they were used as bifacial knives.  They were resharpened by percussion- and pressure-flaking until used-up.  Biface thinning flakes from these heat-treated bifaces were used as blanks for arrowheads in late prehistory.  Projectile points from throughout prehistory were often made from Tosawihi opalite, indicating that flake blanks for points were exported in large numbers from the quarry, perhaps collected from the flakes created in making the Tosawihi bifacial knives.

Tosawihi stone is unusual in that it fluoresces green under black light.  Some variants are speckled with varying amounts of cinnabar, the red sulphide version of mercury.  A curious aspect of the cinnabar in the Tosawihi opalite is that although appearing red when freshly knapped, it changes colour when exposed to the sun, eventually changing to a blue or blue-grey colour.  Thick deposits of high-quality multicoloured opalite ‘jaspers’ also occurred at the Tosawihi quarries, although these stone deposits have been destroyed by mining.