A bar-shaped hematite object, broken at one end and originally part of a longer piece, was found at San Lorenzo, Veracruz, Mexico, and dates to the Early Formative Olmec period, earlier than 1000 BC. When floated on liquid mercury it consistently orients in the same direction, 35.5 degrees west of magnetic north. Analysis by Mössbauer spectraltechnique to determine the composition and structure showed the material to be essentially pure hematite. The total magnetic vector was determined with a spinner magnetometer. It is concluded that this object was a second-order, or zeroth-order compass, i.e. its self-orienting properties were used with no knowledge of its tendency to point N-S. This evidently pre-dates the Chinese discovery of the lodestone compass by more than a millenium. -- AATA