Marengo McHenry County, Illinois, USA Found 1991 September Ordinary chondrite (L6) One stone of 68 g was found among rock piles on the side of a cultivated farm field by James A. Wotal and his son, Alex. Analysis and classification, olivine Fa25.0, pyroxene Fs21.2, Edward J. Olsen, Field Museum of Natural History, Chicago. Information, main mass and thin section used for classification, P. P. Sipiera, Schmitt Meteorite Research Group, Harper College, 1200 W. Algonquin Road, Palatine, Illinois 60067, USA. Source