Winonaite

Winonaites are a group of primitive achondrite meteorites. Like all primitive achondrites, winonaites share similarities with chondrites and achondrites. They show signs of metamorphism, partial melting, brecciation and relic chondrules. Their chemical and mineralogical composition lies between H und E chondrites.

Naming and history

The winonaite group is named after the type specimen, the Winona meteorite. The name itself derived from Winona, Arizona where the type specimen was said to be found during an archaeological excavation of the Sinagua village Elden Pueblo in September 1928. The Sinagua lived in the village between 1150 to 1275. The meteorite was said to be retrieved from the cist of one of the rooms. However, a later study indicates the meteorite was found at another Sinagua site and not in Elden Pueblo. Currently 25 meteorites are included in the winonaite group.

Description

Winonaites are achondrites that have a chemical and mineral composition similar to chondrites. Their composition lies between H and E chondrites. Their isotopic ratios are similar to the silicate inclusions in IAB meteorites. In thin section, the mineral grains show microstructures of extensive thermal metamorphism and signs of partial melting. Some winonaite specimen appear to have relics of chondrules (e.g. Pontlyfni and Mount Morris).