samarium monosulfide
... that samarium monosulfide changes color from black to golden when scratched?
... that <b id="mwFVg"><a href="./Samarium_monochalcogenides" id="mwFVk" rel="mw:WikiLink" title="Samarium monochalcogenides">samarium monosulfide</a></b> changes color from black to golden when scratched?