The mint told reporters that at the beginning of this month there were 5,741 gold retailers in the country.
Since January 2014 some 1,126 used-gold shops had closed down, the mint said.
New rules regulating the business came into force on Monday such as shops no longer being able to pay more than €250 in cash and the obligation to put the prices they buy gold and other precious metals at in their windows.
The shops are also going to have to have closed circuit TV cameras and keep their recordings for 90 days.
Portugal has exported tons of used-gold in the years since the crisis hit, most of it going to Belgium at knock-down prices.