This quartzite hammerstone is from the Tosawihi opalite quarry near Battle Mountain in northern Nevada.  Thousands of hammerstones were used to make bifaces and then discarded at the quarry.   This one was originally spherical but was sheared in half during use.  It likely dates to the Late Holocene period.

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The hammerstone in this model is made from relatively fine-grained quartzite.  Quartzite is not locally available at the quarry, so the stone must have been procured elsewhere and carried in.  The hammerstone is relatively small and use-wear attrition and/or deliberate shaping created a spherical shape.  This suggests that the hammerstone was frequently rotated during use.  It is broken in half.  Spherical hammerstones are relatively common at the quarry, and their shape is very different to the larger, disc-shaped hammerstones also found there.  The spherical hammerstone was probably used in the later stages of making Tosawihi bifaces.

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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.