Quartz, the most common mineral on earth, is almost universally associated with shamans. Why this ritual association occurred worldwide has remained unexplained scientifically, at least in part because western scientific thinking assumes that religious beliefs and practices are epiphenomenal and not worthy of study. This association is archaeologi-cally evident at Sally's Rocksheiter, a small rock engraving-vision quest site in the Mojave Desert, where quartz rocks were placed as offerings in cracks around the rock art panel. SEM and electron microprobe foreign materials analyses of Mojave rock engravings show that the association between quartz and rock art was common: almost 65 per cent contained remnants of quartz hammerstones, used to peck the motifs. A combination of ethnohistory and physical sciences explains why quartz, shamans and vision questing were so strongly associated: triboluminescence causes quartz to glow when struck or abraded, which was believed a visible manifestation of supernatural power. Recognition that this belief and behavioural association were based on quartz's physical properties aids our ability to identify the antiquity of the vision quest in the far west, suggesting that Mojave Desert shamanism is the oldest continuously practiced religious tradition so far identified in the world.
