We present an experimental investigation of the triboelectric charging behavior of lunar simulant (JSC‐1). Our experimental approach ensures that the JSC‐1 particles only make contact to other JSC‐1 particles during the charging process (and no other surfaces). The results show that charge segregation occurs such that smaller particles tend to charge negatively and larger particles charge positively. This particle‐size‐dependent charging follows behavior observed for other single‐component granular systems and appears to be universal.