Green’s Dictionary of Slang

(US drugs) to change the shape of cocaine flakes so they resemble ‘rock’.

1989

(con. 1982–6) T. Williams Cocaine Kids (1990) 40: This was called ‘recompressed’ cocaine. Kitty explained. ‘Recompressed is like when you take coke and put some cut into it and make rocks so the person who buys it thinks that it’s pure, but actually it’s been cut’ [...] Another method, ‘reconstituted’ [...] is the same thing except you gotta do it with a machine.