Ah, I used Array.instance_methods but I see that it requires an agument of "true" to get the inherited and mix-in methods also. ( 98 methods )
(Array.instance_methods(true) - Object.methods).sort
["&", "*", "+", "-", "<<", "[]", "[]=", "all?", "any?", "assoc", "at", "clear", "collect", "collect!", "compact", "compact!", "concat", "cross", "delete", "delete_at", "delete_if", "detect", "distance", "distance_to_line", "distance_to_plane", "dot", "each", "each_index", "each_with_index", "empty?", "entries", "fetch", "fill", "find", "find_all", "first", "flatten", "flatten!", "grep", "index", "indexes", "indices", "inject", "insert", "join", "last", "length", "map", "map!", "max", "member?", "min", "nitems", "normalize", "normalize!", "offset", "offset!", "on_line?", "on_plane?", "pack", "partition", "pop", "project_to_line", "project_to_plane", "push", "rassoc", "reject", "reject!", "replace", "reverse", "reverse!", "reverse_each", "rindex", "select", "shift", "size", "slice", "slice!", "sort", "sort!", "sort_by", "to_ary", "transform", "transform!", "transpose", "uniq", "uniq!", "unshift", "values_at", "vector_to", "x", "x=", "y", "y=", "z", "z=", "zip", "|"]