Gold Blocks are objects that first appeared in New Super Mario Bros. 2. They are regular Coin Blocks, when hit multiple times it will turn in a Gold Block in which Mario can wear on his head. In this form, Coins will pop out of the top when Mario moves. The faster you run, the more coins you get. The block is similar to the Question Box from Super Mario 3D Land and Super Mario 3D World.
Gold Blocks reappear in Super Mario: Elemental Journey with the same mechanics that they had in their game of origin.