LL chondrite
LL chondrites are ordinary chondrites with the least iron and metal of the three groups.
LL stands for low total iron and low metal. These are the most oxidised of the ordinary chondrites: much of their iron sits in silicate minerals rather than as metal, so their olivine has a fayalite content of roughly Fa27 to Fa32, and they contain only a few per cent metal. Many LL chondrites are breccias, rocks made of broken fragments cemented together.
LL chondrites gave science one of its clearest links between a meteorite group and a known asteroid. In 2010 the Japanese Hayabusa spacecraft returned grains from the S-type asteroid Itokawa, and analyses showed they match equilibrated LL chondrites closely. The superbolide that burst over Chelyabinsk in 2013 dropped LL5 chondrite, and the historic Ensisheim stone of 1492 is an LL6.
LL chondrites are only weakly attracted to a magnet and may feel a little lighter than other ordinary chondrites. On a cut face, metal flecks are sparse, and in less-heated examples the chondrules can be large and easy to see. A laboratory measurement of olivine composition or oxygen isotopes is needed to confirm the group.
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