ALetPub 272(9) :ܘܠܘܩܒܠ ܐܘܟܡ̈ܐ ܒܕܡܘܬܗܘܢ܂ ܫ݁ܚܡܐ‏ : like them (the mirror) becomes black facing black things
See the entire entry for šḥm vb. to be black