gems, archaeology, archaeogemology, analytical, geology, Red Sea, olivine basalts

Lava-cave entrances have been observed in several parts of Harrat Khaybar, Saudi Arabia, and one lava tube has been surveyed. Strings of collapses up to 25 km long indicate the possibility that very long caves may be found in this lava field. The fact that an important ancient caravan trail skirts the western fringe of Harrat Khaybar suggests that archaeological studies of caves in this area may prove fruitful.