Avodah Zarah, Chapter Three, Mishnah Two
This mishnah discusses the permissibility of broken pieces of potentially idolatrous images.
1) One who finds fragments of images, behold they are permitted.
a) If one found the figure of a hand or the figure of a foot, behold it is prohibited because such an object is worshipped.
One who finds a fragment of an image may make use of that fragment. The mishnah teaches that we may assume that the non-Jew intentionally broke the idol and thereby annulled it from its idolatrous use.
However, if one finds an entire hand of an image or a foot, it is prohibited, since there are non-Jews who use these parts in and of themselves as idols. The Talmud explains that these are only prohibited if they are found attached to a base, which means that they are not truly broken pieces.