gold dust
noun [ U ] uk/ˈɡəʊld ˌdʌst/ us/ˈɡoʊld ˌdʌst/
金粉;砂金;金末
gold in powder form
Idiom
like gold dustidiom mainly UK 难以得到，不可多得
said about something that is very difficult to get because a lot of people want it
Tickets for the concert are like gold dust. 这场音乐会真是一票难求。