Business and Significant Accounting Policies	3 Months Ended
Mar. 31, 2020
Accounting Policies [Abstract]
Business and Significant Accounting Policies	Business and company formation Solitario Zinc Corp. (“Solitario,” or the “Company”) is an exploration stage company as defined in Industry Guide 7, as issued by the United States Securities and Exchange Commission (“SEC”). Solitario was incorporated in the state of Colorado on November 15, 1984 as a wholly-owned subsidiary of Crown Resources Corporation ("Crown"). In July 1994, Solitario became a publicly traded company on the Toronto Stock Exchange (the "TSX") through its initial public offering. Solitario has been actively involved in mineral exploration since 1993. Solitario’s primary business is to acquire exploration mineral properties or royalties and/or discover economic deposits on its mineral properties and advance these deposits, either on its own or through joint ventures, up to the development stage. At that point, or sometime prior to that point, Solitario would likely attempt to sell its mineral properties, pursue their development either on its own, or through a joint venture with a partner that has expertise in mining operations, or create a royalty with a third party that continues to advance the property. Solitario is primarily focused on the acquisition and exploration of zinc-related exploration mineral properties; however Solitario will evaluate and acquire other base and precious metal mineral exploration properties. In addition to focusing on its mineral exploration properties and the evaluation of mineral properties for acquisition, Solitario also evaluates potential strategic transactions for the acquisition of new precious and base metal properties and assets with exploration potential or business combinations that Solitario determines to be favorable to Solitario. Solitario has recorded revenue in the past from the sale of mineral property, including (i) the sale of certain mineral royalty properties to SilverStream SEZC, a private Cayman Island royalty and streaming company (“SilverStream”) for Cdn$600,000 in January 2019 (the “Royalty Sale”), and (ii) the sale in June 2018 of its interest in the royalty on its Yanacocha property. In addition, Solitario has received proceeds from (i) the sale in 2015 of its former interest in Mount Hamilton LLC (“MH-LLC”), the owner of its former Mt. Hamilton project; (ii) the sale of a royalty on its former Mt. Hamilton project and (iii) joint venture property payments. Revenues and / or proceeds from the sale or joint venture of properties or assets, although significant when they occur, have not been a consistent annual source of cash and would only occur in the future, if at all, on an infrequent basis. Solitario currently considers its carried interest in the Florida Canyon project in Peru and its interest in the Lik project in Alaska to be its core mineral property assets. Nexa Resources, Ltd. (“Nexa”), Solitario’s joint venture partner, is expected to continue the exploration and furtherance of the Florida Canyon project and Solitario is monitoring progress at Florida Canyon. Solitario is working with its 50% joint venture partner in the Lik deposit, Teck American Incorporated, a wholly-owned subsidiary of Teck Resources Limited (both companies are referred to as “Teck”), to further the exploration and evaluate potential development plans for the Lik project. As of March 31, 2020, Solitario has significant balances of cash and short-term investments that Solitario anticipates using, in part, to fund costs and activities intended to further the exploration of the Florida Canyon and Lik projects and to potentially acquire additional mineral property assets. The fluctuations in precious metal and other commodity prices contribute to a challenging environment for mineral exploration and development, which has created opportunities as well as challenges for the potential acquisition of early-stage and advanced mineral exploration projects or other related assets at potentially attractive terms. The accompanying interim condensed consolidated financial statements of Solitario for the three months ended March 31, 2020 are unaudited and are prepared in accordance with accounting principles generally accepted in the United States of America (“generally accepted accounting principles”). They do not include all disclosures required by generally accepted accounting principles for annual financial statements, but in the opinion of management, include all adjustments necessary for a fair presentation. Interim results are not necessarily indicative of results, which may be achieved in the future, or for the full year ending December 31, 2020. These financial statements should be read in conjunction with the financial statements and notes thereto which are included in Solitario’s Annual Report on Form 10-K for the year ended December 31, 2019. The accounting policies set forth in those annual financial statements are the same as the accounting policies utilized in the preparation of these financial statements, except as modified for appropriate interim financial statement presentation. Risks and Uncertainties Solitario faces risks related to health epidemics and other outbreaks of communicable diseases, which could significantly disrupt its operations and may materially and adversely affect our business and financial conditions. Solitario’s business could be adversely impacted by the effects of the coronavirus (COVID-19) or other epidemics or pandemics. The extent to which the coronavirus impacts Solitario’s business, including our exploration and other activities and the market for its securities, will depend on future developments, which are highly uncertain and cannot be predicted at this time, and include the duration, severity and scope of the outbreak and the actions taken to contain or treat the coronavirus outbreak. Solitario has taken steps to conserve its financial resources including reducing costs, in response to the economic uncertainty associated with these risks. See Item 1A “Risk Factors” below. Financial reporting The consolidated financial statements include the accounts of Solitario and its wholly-owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation. The consolidated financial statements are prepared in accordance with generally accepted accounting principles and are expressed in U.S. dollars. Revenue recognition Solitario has recorded revenue from the sale of exploration mineral properties and joint venture property payments. Solitario’s policy is to recognize revenue from the sale of its exploration mineral properties (those without reserves) on a property by property basis, computed as the cash received and / or collectable receivables less any capitalized cost. Payments received for the sale of exploration property interests that are less than the properties cost are recorded as a reduction of the related property's capitalized cost. In addition, Solitario’s policy is to recognize revenue on any receipts of joint venture property payments in excess of its capitalized costs on a property that Solitario may lease to another mining company. Solitario has recognized revenue during the three months ended March 31, 2019 of $408,000 related to the Royalty Sale in accordance with Accounting Standards Codification (“ASC”) 606. Solitario expects any property, royalty or asset sales in the future to be on an infrequent basis. Solitario does not expect to record joint venture property payments on any of its currently held properties for the foreseeable future. Historically, Solitario’s revenues have been infrequent and significant individual transactions and have only been from sales to well known or vetted mining companies. Solitario has never had a return on any of its sales recorded as revenue in its history and does not anticipate it will recognize any estimated returns on its current or future recorded revenues. Use of estimates The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Some of the more significant estimates included in the preparation of Solitario's financial statements pertain to: (i) the recoverability of mineral properties related to its mineral exploration properties and their future exploration potential; (ii) the fair value of stock option grants to employees; (iii) the ability of Solitario to realize its deferred tax assets; (iv) Solitario's investment in marketable equity securities; and (v) the collectability of the SilverStream Note (as defined below). In performing its activities, Solitario has incurred certain costs for mineral properties. The recovery of these costs is ultimately dependent upon the sale of mineral property interests or the development of economically recoverable ore reserves and the ability of Solitario or its joint venture partners to obtain the necessary permits and financing to successfully place the properties into production, and upon future profitable operations, none of which is assured. Cash equivalents Cash equivalents include investments in highly liquid money-market securities with original maturities of three months or less when purchased. As of March 31, 2020, $425,000 of Solitario’s cash and cash equivalents are held in brokerage accounts and foreign banks, which are not covered under the Federal Deposit Insurance Corporation (“FDIC”) rules for the United States. Short-term investments As of March 31, 2020, Solitario has $6,325,000 of its current assets in United States Treasury Securities (“USTS”) with maturities of 15 days to 15 months. In addition, Solitario has two bank certificates of deposits (“CD’s”) each with a face value of $250,000. The USTS and CD’s are recorded at their fair value, based upon quoted market prices. The USTS are not covered under the FDIC insurance rules for United States deposits. Solitario’s USTS and CD’s are highly liquid and may be sold in their entirety at any time at their quoted market price and are classified as a current asset. Mineral properties Solitario expenses all exploration costs incurred on its mineral properties prior to the establishment of proven and probable reserves through the completion of a feasibility study. Initial acquisition costs of its mineral properties are capitalized. Solitario regularly performs evaluations of its investment in mineral properties to assess the recoverability and/or the residual value of its investments in these assets. All long-lived assets are reviewed for impairment whenever events or circumstances change which indicate the carrying amount of an asset may not be recoverable, utilizing established guidelines based upon undiscounted future net cash flows from the asset or upon the determination that certain exploration properties do not have sufficient potential for economic mineralization. Leases Solitario accounts for its leases in accordance with ASC 842, Leases (“ASC 842”) by recognizing right-of-use assets and lease liabilities on the condensed consolidated balance sheet and disclosing key information about lease arrangements. Solitario has elected the practical expedient option to use January 1, 2019, the effective date of adoption of ASC 842, as the initial date of transition and not to restate comparative prior periods and to carry forward historical lease classification. In addition, Solitario has elected the option not to apply the recognition of assets and liabilities provisions of ASC 842 to operating leases with initial terms of less than one year. See Note 4 “Operating Leases” for more information and disclosures regarding Solitario’s leases. Derivative instruments Solitario accounts for its derivative instruments in accordance with ASC 815. Solitario has entered into covered calls from time to time on its investment in Kinross Gold Corporation (“Kinross”) marketable equity securities. Solitario has not designated its covered calls as hedging instruments and any changes in the fair value of the covered calls are recognized in the statement of operations in the period of the change as gain or loss on derivative instruments, and as a change to operating activities in the statement of cash flows for the non-cash portion of the gain or loss. Fair value ASC 820 established a framework for measuring fair value of financial instruments and required disclosures about fair value measurements. For certain of Solitario's financial instruments, including cash and cash equivalents and accounts payable, the carrying amounts approximate fair value due to their short-term maturities. Solitario's short-term investments in USTS and CD’s, its marketable equity securities and any covered call options against those marketable equity securities are carried at their estimated fair value based on quoted market prices. See Note 6, “Fair Value,” below. Marketable equity securities Solitario's investments in marketable equity securities are carried at fair value, which is based upon quoted prices of the securities owned. Solitario records investments in marketable equity securities for investments in publicly traded marketable equity securities for which it does not exercise significant control and where Solitario has no representation on the board of directors of those companies and exercises no control over the management of those companies. The cost of marketable equity securities sold is determined by the specific identification method. Changes in fair value are recorded as unrealized gain or loss in the condensed consolidated statement of operations. Foreign exchange The United States dollar is the functional currency for all of Solitario's foreign subsidiaries. Although Solitario's South American exploration activities during 2019 and the first quarter of 2020 were conducted primarily in Peru, a portion of the payments under land, leasehold and exploration agreements of Solitario are denominated in United States dollars. Realized foreign currency gains and losses are included in the results of operations in the period in which they occur. Income taxes Solitario accounts for income taxes in accordance with ASC 740, “Accounting for Income Taxes” (“ASC 740”). Under ASC 740, income taxes are provided for the tax effects of transactions reported in the financial statements and consist of taxes currently due plus deferred taxes related to certain income and expenses recognized in different periods for financial and income tax reporting purposes. Deferred tax assets and liabilities represent the future tax return consequences of those differences, which will either be taxable or deductible when the assets and liabilities are recovered or settled. Deferred taxes are also recognized for operating losses and tax credits that are available to offset future taxable income and income taxes, respectively. A valuation allowance is provided if it is more likely than not that some portion or all of the deferred tax assets will not be realized. Accounting for uncertainty in income taxes ASC 740 clarifies the accounting for uncertainty in income taxes recognized in a company's financial statements. ASC 740 prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. ASC 740 also provides guidance on derecognition, classification, interest and penalties, accounting in interim periods, disclosure, and transition. ASC 740 provides that a company's tax position will be considered settled if the taxing authority has completed its examination, the company does not plan to appeal, and it is remote that the taxing authority would reexamine the tax position in the future. Earnings per share The calculation of basic and diluted earnings (loss) per share is based on the weighted average number of shares of common stock outstanding during the three months ended March 31, 2020 and 2019. Potentially dilutive shares related to outstanding common stock options of 4,373,000 and 4,373,000, respectively, for Solitario common shares for the three months ended March 31, 2020 and 2019 were excluded from the calculation of diluted loss per share because the effects were anti-dilutive. Employee stock compensation and incentive plans Solitario classifies all of its stock options as equity options in accordance with the provisions of ASC 718, “Compensation – Stock Compensation.” Recently adopted accounting pronouncements The Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurements of Credit Losses on Financial Statements (“ASU No. 2016-13”). Among other things, these amendments require the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Financial institutions and other organizations will now use forward-looking information to better inform their credit loss estimates. ASU No. 2016-13 is effective for Solitario for fiscal year, and interim periods within those fiscal years, beginning after December 15, 2019. Solitario adopted ASU No. 2016-13 effective January 1, 2020 which did not have a material impact on its consolidated financial position or results of operations as of or for the three months ended March 31, 2020. The FASB issued ASU No. 2018-13, Disclosure Framework – Fair Value (topic 820): Changes to Disclosure Requirements for Fair Value Measurement (“ASU No. 2018-13”). Among other things, these amendments change the required disclosures regarding (i) transfers between Level 1 and Level 2 fair values; (ii) unrealized gains / losses included in earnings and other comprehensive income for Level 3 instruments; and (iii) amount, reason and policies regarding transfers between Levels. ASU No. 2018-13 is effective for Solitario for fiscal year, and interim periods within those fiscal years, beginning after December 15, 2019. Solitario adopted ASU No. 2016-13 January 1, 2020 which did not have a material impact on its consolidated financial position or results of operations as of or for the three months ended March 31, 2020. Recently issued accounting pronouncements The SEC has adopted amendments to its disclosure rules to modernize the mineral property disclosure requirements for issuers whose securities are registered with the SEC. These amendments became effective February 25, 2019 (the “SEC Modernization Rules”) and, following a two-year transition period, the SEC Modernization Rules will replace the historical property disclosure requirements for mining registrants that are included in SEC Industry Guide 7. Under the SEC Modernization Rules, consistent with global standards as embodied by the Committee for Reserves International Reporting Standards (“CRIRSCO”), registrants will be required to disclose specified information concerning mineral resources that have been identified on one or more of its mineral properties. Consistent with CRIRSCO standards the SEC Modernization Rules have added definitions to recognize “Measured Mineral Resources”, “Indicated Mineral Resources” and “Inferred Mineral Resources.” The Company is not required to provide disclosure on its mineral properties under the SEC Modernization Rules until its fiscal year beginning January 1, 2021. Upon adoption of the SEC Modernization Rules, among other requirements, the Company will be required to report its mineral resources, if any, as Measured, Indicated or Inferred Mineral Resources in accordance with the SEC Modernization Rules. This will allow investors to evaluate the Company’s resources on a comparable basis with other mining and exploration issuers registered with the SEC. In addition, the SEC Modernization Rules will require the Company to disclose exploration results, mineral reserves, if any, and mineral resources based upon information and supporting documentation prepared by a mining expert (the “qualified person”). The SEC Modernization Rules will require the Company to obtain a dated and signed technical report summary from the qualified person identifying and summarizing the information reviewed and conclusions reached by the qualified person(s) about the mineral resources or reserves for each mineral property. The Company is currently evaluating the requirements under the SEC Modernization Rules and has not determined what effect adoption will have on its consolidated financial statements and disclosures.

Business and Significant Accounting Policies

3 Months Ended

Mar. 31, 2020

Business and Significant Accounting Policies

Business and company formation

Solitario Zinc Corp. (“Solitario,” or the “Company”) is an exploration stage company as defined in Industry Guide 7, as issued by the United States Securities and Exchange Commission (“SEC”). Solitario was incorporated in the state of Colorado on November 15, 1984 as a wholly-owned subsidiary of Crown Resources Corporation ("Crown"). In July 1994, Solitario became a publicly traded company on the Toronto Stock Exchange (the "TSX") through its initial public offering. Solitario has been actively involved in mineral exploration since 1993. Solitario’s primary business is to acquire exploration mineral properties or royalties and/or discover economic deposits on its mineral properties and advance these deposits, either on its own or through joint ventures, up to the development stage. At that point, or sometime prior to that point, Solitario would likely attempt to sell its mineral properties, pursue their development either on its own, or through a joint venture with a partner that has expertise in mining operations, or create a royalty with a third party that continues to advance the property. Solitario is primarily focused on the acquisition and exploration of zinc-related exploration mineral properties; however Solitario will evaluate and acquire other base and precious metal mineral exploration properties. In addition to focusing on its mineral exploration properties and the evaluation of mineral properties for acquisition, Solitario also evaluates potential strategic transactions for the acquisition of new precious and base metal properties and assets with exploration potential or business combinations that Solitario determines to be favorable to Solitario.

Solitario has recorded revenue in the past from the sale of mineral property, including (i) the sale of certain mineral royalty properties to SilverStream SEZC, a private Cayman Island royalty and streaming company (“SilverStream”) for Cdn$600,000 in January 2019 (the “Royalty Sale”), and (ii) the sale in June 2018 of its interest in the royalty on its Yanacocha property. In addition, Solitario has received proceeds from (i) the sale in 2015 of its former interest in Mount Hamilton LLC (“MH-LLC”), the owner of its former Mt. Hamilton project; (ii) the sale of a royalty on its former Mt. Hamilton project and (iii) joint venture property payments. Revenues and / or proceeds from the sale or joint venture of properties or assets, although significant when they occur, have not been a consistent annual source of cash and would only occur in the future, if at all, on an infrequent basis.

Solitario currently considers its carried interest in the Florida Canyon project in Peru and its interest in the Lik project in Alaska to be its core mineral property assets. Nexa Resources, Ltd. (“Nexa”), Solitario’s joint venture partner, is expected to continue the exploration and furtherance of the Florida Canyon project and Solitario is monitoring progress at Florida Canyon. Solitario is working with its 50% joint venture partner in the Lik deposit, Teck American Incorporated, a wholly-owned subsidiary of Teck Resources Limited (both companies are referred to as “Teck”), to further the exploration and evaluate potential development plans for the Lik project.

As of March 31, 2020, Solitario has significant balances of cash and short-term investments that Solitario anticipates using, in part, to fund costs and activities intended to further the exploration of the Florida Canyon and Lik projects and to potentially acquire additional mineral property assets. The fluctuations in precious metal and other commodity prices contribute to a challenging environment for mineral exploration and development, which has created opportunities as well as challenges for the potential acquisition of early-stage and advanced mineral exploration projects or other related assets at potentially attractive terms.

The accompanying interim condensed consolidated financial statements of Solitario for the three months ended March 31, 2020 are unaudited and are prepared in accordance with accounting principles generally accepted in the United States of America (“generally accepted accounting principles”). They do not include all disclosures required by generally accepted accounting principles for annual financial statements, but in the opinion of management, include all adjustments necessary for a fair presentation. Interim results are not necessarily indicative of results, which may be achieved in the future, or for the full year ending December 31, 2020.

These financial statements should be read in conjunction with the financial statements and notes thereto which are included in Solitario’s Annual Report on Form 10-K for the year ended December 31, 2019. The accounting policies set forth in those annual financial statements are the same as the accounting policies utilized in the preparation of these financial statements, except as modified for appropriate interim financial statement presentation.

Risks and Uncertainties

Solitario faces risks related to health epidemics and other outbreaks of communicable diseases, which could significantly disrupt its operations and may materially and adversely affect our business and financial conditions.

Solitario’s business could be adversely impacted by the effects of the coronavirus (COVID-19) or other epidemics or pandemics. The extent to which the coronavirus impacts Solitario’s business, including our exploration and other activities and the market for its securities, will depend on future developments, which are highly uncertain and cannot be predicted at this time, and include the duration, severity and scope of the outbreak and the actions taken to contain or treat the coronavirus outbreak. Solitario has taken steps to conserve its financial resources including reducing costs, in response to the economic uncertainty associated with these risks. See Item 1A “Risk Factors” below.

Financial reporting

The consolidated financial statements include the accounts of Solitario and its wholly-owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation. The consolidated financial statements are prepared in accordance with generally accepted accounting principles and are expressed in U.S. dollars.

Revenue recognition

Solitario has recorded revenue from the sale of exploration mineral properties and joint venture property payments. Solitario’s policy is to recognize revenue from the sale of its exploration mineral properties (those without reserves) on a property by property basis, computed as the cash received and / or collectable receivables less any capitalized cost. Payments received for the sale of exploration property interests that are less than the properties cost are recorded as a reduction of the related property's capitalized cost. In addition, Solitario’s policy is to recognize revenue on any receipts of joint venture property payments in excess of its capitalized costs on a property that Solitario may lease to another mining company.

Solitario has recognized revenue during the three months ended March 31, 2019 of $408,000 related to the Royalty Sale in accordance with Accounting Standards Codification (“ASC”) 606. Solitario expects any property, royalty or asset sales in the future to be on an infrequent basis. Solitario does not expect to record joint venture property payments on any of its currently held properties for the foreseeable future. Historically, Solitario’s revenues have been infrequent and significant individual transactions and have only been from sales to well known or vetted mining companies. Solitario has never had a return on any of its sales recorded as revenue in its history and does not anticipate it will recognize any estimated returns on its current or future recorded revenues.

Use of estimates

The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Some of the more significant estimates included in the preparation of Solitario's financial statements pertain to: (i) the recoverability of mineral properties related to its mineral exploration properties and their future exploration potential; (ii) the fair value of stock option grants to employees; (iii) the ability of Solitario to realize its deferred tax assets; (iv) Solitario's investment in marketable equity securities; and (v) the collectability of the SilverStream Note (as defined below).

In performing its activities, Solitario has incurred certain costs for mineral properties. The recovery of these costs is ultimately dependent upon the sale of mineral property interests or the development of economically recoverable ore reserves and the ability of Solitario or its joint venture partners to obtain the necessary permits and financing to successfully place the properties into production, and upon future profitable operations, none of which is assured.

Cash equivalents

Cash equivalents include investments in highly liquid money-market securities with original maturities of three months or less when purchased. As of March 31, 2020, $425,000 of Solitario’s cash and cash equivalents are held in brokerage accounts and foreign banks, which are not covered under the Federal Deposit Insurance Corporation (“FDIC”) rules for the United States.

Short-term investments

As of March 31, 2020, Solitario has $6,325,000 of its current assets in United States Treasury Securities (“USTS”) with maturities of 15 days to 15 months. In addition, Solitario has two bank certificates of deposits (“CD’s”) each with a face value of $250,000. The USTS and CD’s are recorded at their fair value, based upon quoted market prices. The USTS are not covered under the FDIC insurance rules for United States deposits. Solitario’s USTS and CD’s are highly liquid and may be sold in their entirety at any time at their quoted market price and are classified as a current asset.

Mineral properties

Solitario expenses all exploration costs incurred on its mineral properties prior to the establishment of proven and probable reserves through the completion of a feasibility study. Initial acquisition costs of its mineral properties are capitalized. Solitario regularly performs evaluations of its investment in mineral properties to assess the recoverability and/or the residual value of its investments in these assets. All long-lived assets are reviewed for impairment whenever events or circumstances change which indicate the carrying amount of an asset may not be recoverable, utilizing established guidelines based upon undiscounted future net cash flows from the asset or upon the determination that certain exploration properties do not have sufficient potential for economic mineralization.

Leases

Solitario accounts for its leases in accordance with ASC 842, Leases (“ASC 842”) by recognizing right-of-use assets and lease liabilities on the condensed consolidated balance sheet and disclosing key information about lease arrangements. Solitario has elected the practical expedient option to use January 1, 2019, the effective date of adoption of ASC 842, as the initial date of transition and not to restate comparative prior periods and to carry forward historical lease classification. In addition, Solitario has elected the option not to apply the recognition of assets and liabilities provisions of ASC 842 to operating leases with initial terms of less than one year. See Note 4 “Operating Leases” for more information and disclosures regarding Solitario’s leases.

Derivative instruments

Solitario accounts for its derivative instruments in accordance with ASC 815. Solitario has entered into covered calls from time to time on its investment in Kinross Gold Corporation (“Kinross”) marketable equity securities. Solitario has not designated its covered calls as hedging instruments and any changes in the fair value of the covered calls are recognized in the statement of operations in the period of the change as gain or loss on derivative instruments, and as a change to operating activities in the statement of cash flows for the non-cash portion of the gain or loss.

Fair value

ASC 820 established a framework for measuring fair value of financial instruments and required disclosures about fair value measurements. For certain of Solitario's financial instruments, including cash and cash equivalents and accounts payable, the carrying amounts approximate fair value due to their short-term maturities. Solitario's short-term investments in USTS and CD’s, its marketable equity securities and any covered call options against those marketable equity securities are carried at their estimated fair value based on quoted market prices. See Note 6, “Fair Value,” below.

Marketable equity securities

Solitario's investments in marketable equity securities are carried at fair value, which is based upon quoted prices of the securities owned. Solitario records investments in marketable equity securities for investments in publicly traded marketable equity securities for which it does not exercise significant control and where Solitario has no representation on the board of directors of those companies and exercises no control over the management of those companies. The cost of marketable equity securities sold is determined by the specific identification method. Changes in fair value are recorded as unrealized gain or loss in the condensed consolidated statement of operations.

Foreign exchange

The United States dollar is the functional currency for all of Solitario's foreign subsidiaries. Although Solitario's South American exploration activities during 2019 and the first quarter of 2020 were conducted primarily in Peru, a portion of the payments under land, leasehold and exploration agreements of Solitario are denominated in United States dollars. Realized foreign currency gains and losses are included in the results of operations in the period in which they occur.

Income taxes

Solitario accounts for income taxes in accordance with ASC 740, “Accounting for Income Taxes” (“ASC 740”). Under ASC 740, income taxes are provided for the tax effects of transactions reported in the financial statements and consist of taxes currently due plus deferred taxes related to certain income and expenses recognized in different periods for financial and income tax reporting purposes. Deferred tax assets and liabilities represent the future tax return consequences of those differences, which will either be taxable or deductible when the assets and liabilities are recovered or settled. Deferred taxes are also recognized for operating losses and tax credits that are available to offset future taxable income and income taxes, respectively. A valuation allowance is provided if it is more likely than not that some portion or all of the deferred tax assets will not be realized.

Accounting for uncertainty in income taxes

ASC 740 clarifies the accounting for uncertainty in income taxes recognized in a company's financial statements. ASC 740 prescribes a recognition threshold and measurement attribute for the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. ASC 740 also provides guidance on derecognition, classification, interest and penalties, accounting in interim periods, disclosure, and transition. ASC 740 provides that a company's tax position will be considered settled if the taxing authority has completed its examination, the company does not plan to appeal, and it is remote that the taxing authority would reexamine the tax position in the future.

Earnings per share

The calculation of basic and diluted earnings (loss) per share is based on the weighted average number of shares of common stock outstanding during the three months ended March 31, 2020 and 2019. Potentially dilutive shares related to outstanding common stock options of 4,373,000 and 4,373,000, respectively, for Solitario common shares for the three months ended March 31, 2020 and 2019 were excluded from the calculation of diluted loss per share because the effects were anti-dilutive.

Employee stock compensation and incentive plans

Solitario classifies all of its stock options as equity options in accordance with the provisions of ASC 718, “Compensation – Stock Compensation.”

Recently adopted accounting pronouncements

The Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurements of Credit Losses on Financial Statements (“ASU No. 2016-13”). Among other things, these amendments require the measurement of all expected credit losses for financial assets held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Financial institutions and other organizations will now use forward-looking information to better inform their credit loss estimates. ASU No. 2016-13 is effective for Solitario for fiscal year, and interim periods within those fiscal years, beginning after December 15, 2019. Solitario adopted ASU No. 2016-13 effective January 1, 2020 which did not have a material impact on its consolidated financial position or results of operations as of or for the three months ended March 31, 2020.

The FASB issued ASU No. 2018-13, Disclosure Framework – Fair Value (topic 820): Changes to Disclosure Requirements for Fair Value Measurement (“ASU No. 2018-13”). Among other things, these amendments change the required disclosures regarding (i) transfers between Level 1 and Level 2 fair values; (ii) unrealized gains / losses included in earnings and other comprehensive income for Level 3 instruments; and (iii) amount, reason and policies regarding transfers between Levels. ASU No. 2018-13 is effective for Solitario for fiscal year, and interim periods within those fiscal years, beginning after December 15, 2019. Solitario adopted ASU No. 2016-13 January 1, 2020 which did not have a material impact on its consolidated financial position or results of operations as of or for the three months ended March 31, 2020.

Recently issued accounting pronouncements

The SEC has adopted amendments to its disclosure rules to modernize the mineral property disclosure requirements for issuers whose securities are registered with the SEC. These amendments became effective February 25, 2019 (the “SEC Modernization Rules”) and, following a two-year transition period, the SEC Modernization Rules will replace the historical property disclosure requirements for mining registrants that are included in SEC Industry Guide 7. Under the SEC Modernization Rules, consistent with global standards as embodied by the Committee for Reserves International Reporting Standards (“CRIRSCO”), registrants will be required to disclose specified information concerning mineral resources that have been identified on one or more of its mineral properties. Consistent with CRIRSCO standards the SEC Modernization Rules have added definitions to recognize “Measured Mineral Resources”, “Indicated Mineral Resources” and “Inferred Mineral Resources.” The Company is not required to provide disclosure on its mineral properties under the SEC Modernization Rules until its fiscal year beginning January 1, 2021.

Upon adoption of the SEC Modernization Rules, among other requirements, the Company will be required to report its mineral resources, if any, as Measured, Indicated or Inferred Mineral Resources in accordance with the SEC Modernization Rules. This will allow investors to evaluate the Company’s resources on a comparable basis with other mining and exploration issuers registered with the SEC. In addition, the SEC Modernization Rules will require the Company to disclose exploration results, mineral reserves, if any, and mineral resources based upon information and supporting documentation prepared by a mining expert (the “qualified person”). The SEC Modernization Rules will require the Company to obtain a dated and signed technical report summary from the qualified person identifying and summarizing the information reviewed and conclusions reached by the qualified person(s) about the mineral resources or reserves for each mineral property. The Company is currently evaluating the requirements under the SEC Modernization Rules and has not determined what effect adoption will have on its consolidated financial statements and disclosures.