Green’s Dictionary of Slang

mint n.1

[8C SE mint, money. The term was wholly sl. by 16C, although the Mint, as a place, remained SE]

1. [16C–mid-19C] (UK Und.) a piece of money.

2. [mid-16C–early 19C] (also mynt) gold.

3. [late 18C+] a great deal of money.

4. [1900s] a great deal.

In derivatives

minted (adj.)

1. (Scot.) excellent, first-rate.

2. [1990s+] wealthy.

mintful (n.)

[1940s+] a large sum of money.