PELE'S HAIR: case studies from Kilauea

Pele’s hair are long, thin strands of basaltic volcanic glass formed when small drops of magma are spun or drawn out by the wind or streams of volcanic gas into long hair-like strands. Named for Pele, the Hawaiian goddess of fire, they are basically found in Hawaiian eruption deposits. Pele’s hair is deep yellow or gold and is commonly found downwind from active vents concentrated in hollows or other low energy ‘traps’. In literature the origin of these thin strands of glass have been linked to fountains from Hawaiian eruptions. Beside the high fountaining, Pele’s hair are actually found in other environments. In this work we investigated in detail the dimensions, surface textures and the nature of Pele’s hair, from four typical environment of formation at Hawaiian volcanoes: high fountaining, weak explosive activity, lava ocean entry and a lava skylight. Samples has been characterized in terms of textural and morphological features, in thin section and under the SEM. Pele’s hair consists of long strands of gold sideromelane, showing variable length, from an half mm to tens of mm, often without surface vesicles and sometimes including Pele’s tears inside or at the end. They are often found incomplete, since they are easily broken on landing or even during transport. Their surfaces are mostly rough, with ‘ploughs’ of different sizes and large cavities. Vesicles are visible in the cross sections of Pele’s hair. There are two mostly size population of bubbles: one elongated and central and parallel to the axis of elongation and the other one smaller, and rounded and dispersed across the cross section of the fibers. Pele’s hair often shows, in thin section, a single inner elongate vesicle in the middle of the fragment linked to bubble coalescence phenomena, along the entire length of the hair. Samples from the four volcanic environments show different features in terms of their shape, surface textures and micro-textures, pointing out that varying degrees of cooling, degassing and shear affect the texture and the processes of formation of Pele’s hair.