25 C.F.R. § 214.4
Lessee shall furnish with each lease at the time it is filed with the officer in charge an acceptable bond not less than the following amounts:
For less than 80 acres$1,000
For 80 acres and less than 120 acres1,500
For 120 acres and not more than 160 acres2,000
For each additional 40 acres, or part thereof above 160 acres500
Provided, That for leases for minerals other than oil and gas the Secretary of the Interior or his authorized representatives with the consent of the Indian landowner may authorize a bond for a lesser amount if, in his opinion, the circumstances warrant and the interests of the Indian landowners are fully protected: Provided further, That the lessee shall be allowed to file bond, Form S covering all leases to which he or they are or may become parties instead of a separate bond in each case, such bond to be in the penal sum of $15,000. The right is reserved to change the amount of the bond in any particular case, or to require a new bond in the discretion of the Secretary of the Interior.
25 C.F.R. §214.4