From shell beads in the Palaeolithic and stone beads in the Neolithic to beautiful artificial gems in modern times, the history of gems has roughly paralleled that of humans. In the beginning, myths and folklore about the healing properties of gemstones dominated the story. Today, the story is about scientific techniques making larger or more colourful gems and newly discovered mineral deposits revealing gemstone treasures. In the western world the written history of precious and semiprecious stones begins with the On Stones of the Greek philosopher and naturalist Theophrastus ( ca . 315 BC) followed by the Natural History of the Roman historian Pliny (77 AD), which was the standard work on gems and minerals for more than a thousand years. The gemstones of the Old Testament and those of ancient East Asia tell their separate stories. Following a brief summary of these early works, this paper continues with individual descriptions of the major gems and semiprecious stones, focusing on their two most important attributes – colour and hardness – as well as where they are found. This is followed by a brief discussion of altered gems and a summary of modern interactions of gems and man. This paper concludes with some personal experiences of the author and a brief introduction to the geology of gem deposits.

The 45 km 2 map area is situated at the south end of the Hot Creek Range in central Nevada, ~16 km east of the buried leading edge of the Mississippian Roberts Mountains thrust. Three eastward-trending left-slip faults divide the area into four structural blocks. The southernmost block is occupied solely by upper Oligocene volcanic rocks. The narrow northernmost block, now occupied surficially by valley fill and volcanic rocks, represents the south end of the main part of the Hot Creek Range, from which the study area is offset. The middle two blocks display different aspects of the eastward-traveled outer crater rim created by the ca. 382 Ma (early Late Devonian, middle Frasnian) Alamo impact. The Alamo impact was produced by a 5-km-diameter bolide, most likely a comet, which excavated a transient submarine crater 44–65 km in diameter. Comparison of thin (8–12 m) Alamo Breccia deposits in the northern of the middle two blocks with a more easterly, thick (35–42 m) Alamo deposit in the main Hot Creek Range, 4 km north of the map area, suggests that these blocks traveled many kilometers eastward. The northern of the middle two blocks contains a large olistolith capped by the thin breccia, whereas the southern block contains a larger olistolith lacking an Alamo Breccia cap. Three Devonian pulses of the Antler orogeny are better documented in the chapter on the Bisoni-McKay area. Here, the first Antler pulse in latest Middle Devonian time is obscured within an ~9 m.y. hiatus enlarged by excavation of the Alamo impact crater. The second Antler pulse is recorded by the ~4 m.y. hiatus produced by the regional unconformity between the lower and upper members of the Woodruff Formation. The third Antler pulse is documented by an ~8 m.y. regional hiatus between the Mississippian Webb Formation and Upper Devonian Woodruff Formation. In previous papers, we had interpreted this pulse to initiate the Antler orogeny.