What is a pallasite?
A pallasite is a stony-iron meteorite made of olivine crystals set in iron-nickel metal. Thin polished slices can glow like stained glass when light shines through the crystals.
Pallasites are often called the most beautiful meteorites. Their olivine crystals, a magnesium-iron silicate whose gem-quality form is known as peridot, range from pale yellow through gold to deep green and are held in a shiny network of metal. The group is named after the German naturalist Peter Simon Pallas, who studied a large mass of this kind found near Krasnoyarsk in Siberia in the eighteenth century and arranged for it to be transported for study.
How did crystals of rock come to float in metal? The traditional answer is that pallasites formed at the boundary between the molten metal core and the olivine-rich mantle of an asteroid, where the two could mingle. More recent work suggests that, at least for some pallasites, a collision may have injected molten metal into mantle rock. Scientists recognise several groups, including the main-group pallasites, the rarer Eagle Station group and the pyroxene pallasites, which probably came from different parent bodies.
Famous examples include Esquel, found in Argentina and renowned for its clear, gemmy olivine; Imilac, from Chile's Atacama Desert; Brenham, from Kansas; Fukang, a mass of about a tonne found in China in 2000; and Seymchan from Russia, first catalogued as an iron meteorite before olivine-rich pieces were recognised.
Pallasites need care. The metal can corrode in humid air, and as it does, the olivine may crack or fall out. Collectors store slices in dry conditions and handle them by the edges. Their rarity, beauty and the fact that they give a rare glimpse of the deep interior of a shattered world make them highly sought after by museums and collectors alike.