On april 2, 2017, montana mining co. pays $3,721,000 for an ore deposit containing 1,525,000 tons. the company installs machinery in the mine costing $213,500, with an estimated seven-year life and no salvage value. the machinery will be abandoned when the ore is completely mined. montana begins mining on may 1, 2017, and mines and sells 166,200 tons of ore during the remaining eight months of 2017.

Given:
April 2, 2017 - paid $3,721,000 for 1,525,000 tons of ore deposit
installed machine costing $213,500. 7 year life. No salvage value. will be abandoned when ore deposit is completely mined. 

May 1, 2017 - mining begins. 166,200 tons of ore mined and sold.

At the end of the year, depletion of the ore deposit and depreciation of the machinery must be recorded.

3,721,000 / 1,525,000 = 2.44 depletion rate per ton
2.44 * 166,200 = 405,528

entry on Dec. 31:                                         Debit                        Credit
Depletion expense - Mineral deposit          405,528
                 Accumulated depletion - Mineral deposit                   405,528

Depreciation of machine is not computed based on straight line method. It is computed based on the ratio of the ore deposit mined and sold to the total ore deposits.

(166,200 / 1,525,000) * 213,500 = 23,268

entry on Dec. 31                                        Debit                   Credit
Depreciation expense - Machinery            23,268
              Accumulated depreciation - Machinery                   23,268