Revenue from oxide plant lease. We recorded revenue of $1.2 million during three-month period ended June 30, 2020, related to the lease of our Velardeña oxide plant to a third party. The Velardeña oxide plant lease was terminated in November 2020. We did not record any revenue during the three-month period ended June 30, 2021.
Oxide plant lease costs. We recorded $0.4 million of costs related to the oxide plant lease during the three-month period ended June 30, 2020. The costs consist primarily of reimbursable labor and utility costs which for accounting purposes are also included in revenue from the oxide plant lease. The Velardeña oxide plant lease was terminated in November 2020. We did not record any costs related to the oxide plant lease during the three-month period ended June 30, 2021.
Exploration expense. Our exploration expense, including property holding costs and allocated administrative expenses, totaled $1.1 million and $0.8 million for the three months ended June 30, 2021, and June 30, 2020, respectively. The higher exploration expense for 2021 is primarily related to increased exploration at our Rodeo operation in Mexico during the period.
Velardeña care and maintenance costs. We recorded $0.1 million and $0.2 million for the three-month periods ended June 30, 2021 and June 30, 2020, respectively, for expenses related to care and maintenance at our Velardeña Properties as the result of the suspension of mining and processing activities in November 2015. The reduced costs for 2021 are primarily the result of costs associated with activities at the Velardeña Properties being allocated to the Rodeo operation.
El Quevar project expense. We incurred $0.1 million and $0.2 million for the three-month periods ended June 30, 2021, and June 30, 2020, respectively, related to holding and evaluation costs for the Yaxtché deposit at our El Quevar project in Argentina. During the three months ended June 30, 2021, approximately $0.2 million of costs actually incurred were offset by an anticipated reimbursement by Barrick, as discussed above.
Administrative expense. Administrative expenses totaled $1.0 million for the three months ended June 30, 2021. Administrative expenses, including costs associated with being a public company, are incurred primarily by our corporate activities in support of the Rodeo Property, Velardeña Properties, El Quevar project and our exploration portfolio. The $1.0 million of administrative expenses we incurred during the three months ended June 30, 2021, is comprised of $0.5 million of employee compensation and directors’ fees, $0.2 million of professional fees and $0.3 million of insurance, rents, travel expenses, utilities and other office costs. Administrative expenses totaled $0.8 million for the three months ended June 30, 2020. The $0.8 million of administrative expenses we incurred during the three months of 2020 is comprised of $0.4 million of employee compensation and directors’ fees, $0.3 million of professional fees and $0.1 million of insurance, rents, travel expenses, utilities and other office costs.
Stock based compensation. During the three months ended June 30, 2021, we incurred approximately $1.0 million of expense related to stock-based compensation. During the three months ended June 30, 2020, we incurred approximately $0.6 million of expense related to stock-based compensation. Stock based compensation varies from period to period depending on the number and timing of shares granted, the type of grant, the market value of the shares on the date of grant and other variables. Stock based compensation was higher in the 2021 period due primarily to stock awards granted to executives and a consultant.
Reclamation and accretion expense. During each of the three months ended June 30, 2021 and June 30, 2020 we incurred approximately $0.1 million of reclamation expense related to the accretion of an asset retirement obligation at the Velardeña Properties and environmental liabilities associated with the Rodeo operation.
Other operating income (expense), net. We recorded $0.1 million of other operating income for the three months ended June 30, 2021, primarily related to the amortization of deferred income related to the option agreement for the sale of the Santa Maria property, as discussed above. We recorded $0.1 million of other operating expense for the three months ended June 30, 2020, related to the write-off of a non-strategic exploration property in Mexico.
Depreciation, depletion and amortization. During the three-month periods ended June 30, 2021, and June 30, 2020, we incurred depreciation, depletion and amortization expense of approximately $0.2 million and $0.3 million, respectively.
Interest and other expense, net. We recorded a nominal amount of interest and other expense, net for both the three-month periods ended June 30, 2021 and June 30, 2020.