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During the Interim Term, the “Interim Price” shall be as follows: (i) FOB mine pricing for 30/50, 40/70 and 100 Mesh Northern White frac sand purchased by Halliburton under the Purchase Agreement shall be $*** per ton, (ii) FOB mine pricing for 20/40 Northern White frac sand purchased by Halliburton under the Purchase Agreement shall be $*** per ton, and (iii) delivered pricing at Supplier’s terminal facilities for all Northern White frac sand purchased by Halliburton during the Interim Term shall be the pricing in Exhibit B or as mutually agreed upon by the Parties at the time of sale. The failure of the Parties to agree upon pricing for Northern White frac sand delivered at Supplier’s terminal facilities shall not relieve Halliburton of its obligation to purchase the Monthly Minimum Interim Requirement as defined in section (b) below. Additional terminal pricing not in Exhibit B will be mutually agreed to between the Parties.

During the Interim Term, Halliburton is obligated to buy from Supplier, and Supplier is obligated to sell, at the Interim Price, *** tons of Northern White frac sand each calendar month (the “Monthly Minimum Interim Requirement”). Halliburton shall be entitled to count both FOB mine and terminal purchases toward the Monthly Minimum Interim Requirement.

During any calendar month of the Interim Term that Halliburton purchases at least the Monthly Minimum Interim Requirement, Halliburton shall be eligible for a rebate, to be paid by Supplier no later than forty-five (45) days following the end of such calendar month, as follows:

If Halliburton meets or exceeds the grade split percentage thresholds set forth on Exhibit A for (A) 30/50 Premium Frac Sand, (B) 40/70 Premium Frac Sand, and (C) 100 mesh sand, then Supplier shall pay Halliburton a rebate equal to $*** multiplied by the number of tons of Northern White frac sand purchased from Supplier during such calendar month.

In addition to Halliburton’s Monthly Minimum Interim Requirement, during each three month quarter of the Interim Term, Halliburton shall use its best efforts to divide its minimum required purchases between Supplier’s mines serviced by the UP and CN railroads as follows: Halliburton shall use its best efforts to purchase at least *** tons of its minimum required purchase of Northern White frac sand under this side letter agreement during each three-month quarter from Supplier’s mines serviced by the UP, and at least *** tons of its minimum required purchase of Northern White frac sand under this side letter agreement during each three-month quarter from Supplier’s mines serviced by the CN. In addition to all other obligations set forth in this letter agreement, Halliburton shall be deemed to have failed to comply with this letter agreement if, for any three month quarter

If Halliburton purchases Northern White frac sand in excess of the Monthly Minimum Interim Requirement during any calendar month of the Interim Term, then such excess tons of Northern White frac sand shall be counted towards Halliburton’s Monthly Minimum Interim Requirement for a subsequent calendar month during the Interim Term. Notwithstanding anything in this letter agreement to the contrary, Supplier shall have no obligation to sell to Halliburton more than *** tons of Northern White frac sand during any calendar month of the Interim Term.

If, after adding any applicable excess tons counted from a prior month in accordance with section (e) above, Halliburton purchases less than the Monthly Minimum Interim Requirement, but more than *** tons of Northern White frac sand, from Supplier in any calendar month during the Interim Term (an “Interim Shortfall Month”), then the “Interim Shortfall” shall be the amount by which the Monthly Minimum Interim Requirement exceeds the amount of Northern White frac sand actually purchased by Halliburton during such Interim Shortfall Month including any applicable excess tons counted from a prior month in accordance with section (e) above. Halliburton shall have sixty (60) days after the end of such Interim Shortfall Month (the “Interim Cure Period”) to purchase tonnage of Northern White frac sand in excess of the Monthly Minimum Interim Requirement to make up for the Interim Shortfall. If the Interim Shortfall Month is the final month of the Interim Term, Halliburton shall be entitled to the Interim Cure Period for the Interim Shortfall for such Interim Shortfall Month, and any rights or obligations that are determined hereunder upon the expiration of the Interim Term shall be delayed until the conclusion of such Interim Cure Period to determine if Halliburton’s obligations herein have been satisfied.

If, after adding any applicable excess tons counted from a prior month in accordance with section (e) above, Halliburton fails to purchase at least *** tons of Northern White frac sand from Supplier in any calendar month during the Interim Term (an “Interim Breach Month”), or if Halliburton fails to fully make up an Interim Shortfall during the Interim Cure Period, then Halliburton shall be deemed to have breached this letter agreement (a “Halliburton Breach”). Halliburton shall have thirty (30) days after written notice from Supplier to cure a Halliburton Breach by purchasing tonnage of Northern White frac sand from Supplier in excess of the Monthly Minimum Interim Requirement in an amount equal to (i) the difference between the Monthly Minimum Interim Requirement and the number of tons of Northern White frac sand purchased by Halliburton from Supplier during the Interim Breach Month including any applicable excess tons counted from a prior month in accordance with section (e) above or (ii) the uncured Interim Shortfall, as applicable. If the time period to cure a Halliburton Breach provided above extends past the end of the Interim Term, Halliburton shall be entitled to the full cure period for such Halliburton Breach, and any rights or obligations that are determined hereunder upon the expiration of the Interim Term shall be delayed until the conclusion of such cure period to determine if Halliburton’s obligations herein have been satisfied. If Halliburton fails to cure a Halliburton Breach or other non-compliance hereunder within thirty (30) days after written notice thereof from Supplier, then this letter agreement and all terms and conditions hereunder shall automatically terminate, and all terms and conditions of the Purchase Agreement shall be reinstated in full force and effect. Notwithstanding the foregoing, if Halliburton has more than one (1) Halliburton Breach during the Interim Term, Supplier shall have the right to immediately terminate this letter agreement by giving written notice of termination to Halliburton and, in the event of such termination, all terms and conditions of the Purchase Agreement shall be reinstated in full force and effect. Supplier hereby reserves all rights and remedies under the Purchase Agreement, including without limitation, any and all rights, remedies and claims which existed for Purchase Shortfalls and Makewhole Payment liability as of the effective date hereof.