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<!--Date of creation: 03/15/2023-->
<!--Software architectural design and coding: A'c Dharmapremananda Avt.-->
<!--Copyright (c) 2023 I-NET Business Solutions, Inc. All Rights Reserved.-->
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  <import namespace="http://fasb.org/srt-types/2022" schemaLocation="https://xbrl.fasb.org/srt/2022/elts/srt-types-2022.xsd" />
  <import namespace="http://www.xbrl.org/dtr/type/2020-01-21" schemaLocation="https://www.xbrl.org/dtr/type/2020-01-21/types.xsd" />
  <import namespace="http://xbrl.sec.gov/stpr/2022" schemaLocation="https://xbrl.sec.gov/stpr/2022/stpr-2022.xsd" />
  <import namespace="http://fasb.org/us-roles/2022" schemaLocation="https://xbrl.fasb.org/us-gaap/2022/elts/us-roles-2022.xsd" />
  <import namespace="http://fasb.org/us-types/2022" schemaLocation="https://xbrl.fasb.org/us-gaap/2022/elts/us-types-2022.xsd" />
  <import namespace="http://fasb.org/srt/2022" schemaLocation="https://xbrl.fasb.org/srt/2022/elts/srt-2022.xsd" />
  <import namespace="http://fasb.org/us-gaap/2022" schemaLocation="https://xbrl.fasb.org/us-gaap/2022/elts/us-gaap-2022.xsd" />
  <element id="sodi_InvestmentsInMarketableEquitySecuritiesAtFairValue" name="InvestmentsInMarketableEquitySecuritiesAtFairValue" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_ExplorationExpenseMineralProperties" name="ExplorationExpenseMineralProperties" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_UnrealizedGainlossOnShortTermInvestments" name="UnrealizedGainlossOnShortTermInvestments" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_LossPerCommonShareAbstract" name="LossPerCommonShareAbstract" nillable="true" abstract="true" xbrli:periodType="duration" type="xbrli:stringItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_IncomeLossPerShareBasicAndDiluted" name="IncomeLossPerShareBasicAndDiluted" nillable="true" xbrli:periodType="duration" type="num:perShareItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_WeightedAverageShareOutstandingBasicAndDiluted" name="WeightedAverageShareOutstandingBasicAndDiluted" nillable="true" xbrli:periodType="duration" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_IssuanceOfSharesOptionExercisesAmount" name="IssuanceOfSharesOptionExercisesAmount" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_IssuanceOfSharesOptionExercisesShares" name="IssuanceOfSharesOptionExercisesShares" nillable="true" xbrli:periodType="duration" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_IssuanceOfSharesAtmNetShares" name="IssuanceOfSharesAtmNetShares" nillable="true" xbrli:periodType="duration" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_IssuanceOfSharesAtmNetAmount" name="IssuanceOfSharesAtmNetAmount" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_IssuanceOfSharesPrivatePlacementShares" name="IssuanceOfSharesPrivatePlacementShares" nillable="true" xbrli:periodType="duration" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_IssuanceOfSharesPrivatePlacementAmount" name="IssuanceOfSharesPrivatePlacementAmount" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_UnrealizedLossGainOnShortTermInvestments" name="UnrealizedLossGainOnShortTermInvestments" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_LossOnSaleOfMarketableEquitySecurities" name="LossOnSaleOfMarketableEquitySecurities" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_MineralPropertyImpairment" name="MineralPropertyImpairment" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_AdditionsToMineralProperty" name="AdditionsToMineralProperty" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_SaleOfDerivativeInstrumentsNet" name="SaleOfDerivativeInstrumentsNet" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_AccruedMineralPropertyAcquisitionCostsIncludedInAccountsPayable" name="AccruedMineralPropertyAcquisitionCostsIncludedInAccountsPayable" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_AcquisitionOfRightToUseAsset" name="AcquisitionOfRightToUseAsset" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_MineralPropertyExplorationExpenseTableTextBlock" name="MineralPropertyExplorationExpenseTableTextBlock" nillable="true" xbrli:periodType="duration" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_MarketableSecuritiesAdjustmentToFairValueTableTextBlock" name="MarketableSecuritiesAdjustmentToFairValueTableTextBlock" nillable="true" xbrli:periodType="duration" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_RealizedAndUnrealizedGainLossOnEquityInvestmentsTableTextBlock" name="RealizedAndUnrealizedGainLossOnEquityInvestmentsTableTextBlock" nillable="true" xbrli:periodType="duration" type="nonnum:textBlockItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_JointVenturesPartner" name="JointVenturesPartner" nillable="true" xbrli:periodType="instant" type="num:percentItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_CashAndCashEquivalentsHeldInBrokerageAccountsAndForeignBanks" name="CashAndCashEquivalentsHeldInBrokerageAccountsAndForeignBanks" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_MaturitiesPeriodOfCurrentAssetsInUnitedStatesTreasurySecurities" name="MaturitiesPeriodOfCurrentAssetsInUnitedStatesTreasurySecurities" nillable="true" xbrli:periodType="duration" type="xbrli:stringItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_CertificatesOfDepositFairValue" name="CertificatesOfDepositFairValue" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_MaturityOfShortTermInvestmentDescription" name="MaturityOfShortTermInvestmentDescription" nillable="true" xbrli:periodType="duration" type="xbrli:stringItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_MineralsPropertyImpairment" name="MineralsPropertyImpairment" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_ReduceReturnRoyaltyRate" name="ReduceReturnRoyaltyRate" nillable="true" xbrli:periodType="instant" type="num:percentItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_ExplorationExpenditures" name="ExplorationExpenditures" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_PaymentOfUnderlyingOwner" name="PaymentOfUnderlyingOwner" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_ObligationToPayTheUnderlyingOwner" name="ObligationToPayTheUnderlyingOwner" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_TotalingUnderlyingOwnerAnnualPayments" name="TotalingUnderlyingOwnerAnnualPayments" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_AvailableForSalesSecuritiesCurrent" name="AvailableForSalesSecuritiesCurrent" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_MarketableEquitySecurityShares" name="MarketableEquitySecurityShares" nillable="true" xbrli:periodType="instant" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_UnrealizedGainLossOnMarketableEquitySecurities" name="UnrealizedGainLossOnMarketableEquitySecurities" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_CostOfMarketableEquitySecuritiesSold" name="CostOfMarketableEquitySecuritiesSold" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_RealizedGainOnMarketableEquitySecuritiesSold" name="RealizedGainOnMarketableEquitySecuritiesSold" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_ProceedsFromTheSaleOfMarketableEquitySecuritiesSold" name="ProceedsFromTheSaleOfMarketableEquitySecuritiesSold" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_MarketablesSecuritiesGainLoss" name="MarketablesSecuritiesGainLoss" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_RealizedGainOnMarketableEquitiesSecuritiesSold" name="RealizedGainOnMarketableEquitiesSecuritiesSold" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_NetGainLossesOnMarketableSecurities" name="NetGainLossesOnMarketableSecurities" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_PurchasedVendettaUnits" name="PurchasedVendettaUnits" nillable="true" xbrli:periodType="duration" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_VendettaUnitsForAggregateConsideration" name="VendettaUnitsForAggregateConsideration" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_PurchasePricePerUnit" name="PurchasePricePerUnit" nillable="true" xbrli:periodType="duration" type="num:perShareItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_ChargedLossOnDerivativeInstruments" name="ChargedLossOnDerivativeInstruments" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_DiscountRate" name="DiscountRate" nillable="true" xbrli:periodType="duration" type="num:percentItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_ImputedInterest" name="ImputedInterest" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_RemainingCashPayments" name="RemainingCashPayments" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_OperatingLeaseTermInMonths" name="OperatingLeaseTermInMonths" nillable="true" xbrli:periodType="duration" type="xbrli:stringItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_UnrealizedLossOnShortTermInvestments" name="UnrealizedLossOnShortTermInvestments" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_LeaseLiability" name="LeaseLiability" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_LeaseAsset" name="LeaseAsset" nillable="true" xbrli:balance="credit" xbrli:periodType="instant" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_IncomeTaxReconciliationExpirationOfCapitalLossCarryovers" name="IncomeTaxReconciliationExpirationOfCapitalLossCarryovers" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_PermanentDifferencesAndOther" name="PermanentDifferencesAndOther" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_ProceedsFromSaleOfCoveredCalls" name="ProceedsFromSaleOfCoveredCalls" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_ShortTermInvestment" name="ShortTermInvestment" nillable="true" xbrli:balance="debit" xbrli:periodType="instant" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_LeaseAndOptionPaymentsForPropertiesSolitarioOwns" name="LeaseAndOptionPaymentsForPropertiesSolitarioOwns" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateFairValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGrantDateFairValue" nillable="true" xbrli:periodType="duration" type="num:perShareItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_GrantDateFairValue" name="GrantDateFairValue" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_NumberOfOptionsExercised" name="NumberOfOptionsExercised" nillable="true" xbrli:periodType="duration" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_WeightedAverageExercisePriceExpired" name="WeightedAverageExercisePriceExpired" nillable="true" xbrli:periodType="duration" type="num:perShareItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_AwardVestingRightsOnGrantDatePercentage" name="AwardVestingRightsOnGrantDatePercentage" nillable="true" xbrli:periodType="duration" type="num:percentItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_AggregateIntrinsicValuePerShare" name="AggregateIntrinsicValuePerShare" nillable="true" xbrli:periodType="instant" type="num:perShareItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_SaleOfSharesOfCommonStock" name="SaleOfSharesOfCommonStock" nillable="true" xbrli:periodType="duration" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_SalePerShareOfsharesofcommonstock" name="SalePerShareOfsharesofcommonstock" nillable="true" xbrli:periodType="duration" type="num:perShareItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_NetProceedsAfterExpenses" name="NetProceedsAfterExpenses" nillable="true" xbrli:balance="credit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_PurchaseShareofcommonstock" name="PurchaseShareofcommonstock" nillable="true" xbrli:periodType="duration" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_CommissionRate" name="CommissionRate" nillable="true" xbrli:periodType="duration" type="num:percentItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_AveragePrice" name="AveragePrice" nillable="true" xbrli:periodType="duration" type="num:perShareItemType" substitutionGroup="xbrli:item" />
  <element id="sodi_NetProceedsAfterCommissionsAndSaleExpenses" name="NetProceedsAfterCommissionsAndSaleExpenses" nillable="true" xbrli:balance="debit" xbrli:periodType="duration" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" />
  <element name="LikProjectAlaskaUSMember" id="sodi_LikProjectAlaskaUSMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="GoldenCrestSouthDakotaUSMember" id="sodi_GoldenCrestSouthDakotaUSMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="VoxRoyaltyCorpMember" id="sodi_VoxRoyaltyCorpMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="GoldenCrestAgreementMember" id="sodi_GoldenCrestAgreementMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="LikPropertyMember" id="sodi_LikPropertyMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="KinrossGoldCorpMember" id="sodi_KinrossGoldCorpMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="VendettaMiningCorpMember" id="sodi_VendettaMiningCorpMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="HighlandSilverCorpMember" id="sodi_HighlandSilverCorpMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="TNRGoldCorpMember" id="sodi_TNRGoldCorpMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="WRLeaseMember" id="sodi_WRLeaseMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="LikProjectEquipmentMember" id="sodi_LikProjectEquipmentMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="VendettaWarrantsMember" id="sodi_VendettaWarrantsMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="ExplorationBondsAndOtherAssetsMember" id="sodi_ExplorationBondsAndOtherAssetsMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="KinrossCallsMember" id="sodi_KinrossCallsMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="Grant3Member" id="sodi_Grant3Member" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="Plan2013Member" id="sodi_Plan2013Member" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="Grant2Member" id="sodi_Grant2Member" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="Grant1Member" id="sodi_Grant1Member" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="TwoThousandAndThirteenPlanMember" id="sodi_TwoThousandAndThirteenPlanMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="ATMAgreementMember" id="sodi_ATMAgreementMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
  <element name="ShareRepurchaseProgramMember" id="sodi_ShareRepurchaseProgramMember" nillable="true" xbrli:periodType="duration" type="nonnum:domainItemType" substitutionGroup="xbrli:item" />
</schema>
