fool's gold
noun [ U ] uk/ˌfuːlz ˈɡəʊld/ us/ˌfuːlz ˈɡoʊld/
愚人金（指看上去像黄金但其实一钱不值的矿物）
a mineral that is found in rocks and looks like gold but is not valuable
误以为会令人愉快（或大获成功）的事物
something that you think will be very pleasant or successful but is not