INCOME TAXES: (Tables)

3 Months Ended

Mar. 31, 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 quarter of 2020 and 2019 consisted of ($ in millions):

	2020			2019
Statutory income tax provision	$	207.4		$	214.7
Peruvian royalty		2.0			0.4
Mexican royalty		8.1			16.7
Peruvian special mining tax		4.2			6.1
Total income tax provision	$	221.7		$	237.9
Effective income tax rate		50.8	%		38.1	%