When I watched the video I saw a machine scoring the mirror to make different shaped mirrors. The workers easily broke off the excess mirror meaning that the mirrors are not strong. Also if you tried to pull the mirror apart it wouldn’t break very easily so a mirror has a very high tensile strength. A mirror is also not malleable at all because if you try to change its form it will shatter. There are a lot of properties I can name that relate to a mirror but it basically is that you cant really change the form of a mirror or it will break.