INCOME TAXES: (Tables)

6 Months Ended

Jun. 30, 2020

INCOME TAXES:

Schedule of income tax provision and effective income tax rate

The income tax provision and the effective income tax rate for the first six months of 2020 and 2019 consisted of ($ in millions):

	2020			2019
Statutory income tax provision	$	406.8		$	429.1
Peruvian royalty		4.3			6.5
Mexican royalty		21.4			35.2
Peruvian special mining tax		13.7			18.2
Total income tax provision	$	446.2		$	489.0
Effective income tax rate		48.2	%		38.1	%