MAJOR SOURCES OF REVENUE (Details) - Sales Revenue - Customer Concentration Risk - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019
Barrick
Major sources of revenue
Revenue	$ 157,972	$ 125,458	$ 99,283
Percentage of total revenue	25.70%	25.20%	23.50%
Centerra
Major sources of revenue
Revenue	$ 156,938	$ 131,425	$ 101,011
Percentage of total revenue	25.50%	26.30%	23.90%
Teck
Major sources of revenue
Revenue	$ 82,164	$ 74,219	$ 69,264
Percentage of total revenue	13.30%	14.90%	16.40%