EXHIBIT 99(b) SECTION 906 CERTIFICATION BY THE CHIEF FINANCIAL OFFICER I, M. Michael Owens, Chief Financial Officer of United States Lime & Minerals, Inc. (the "Company"), hereby certify that to my knowledge: (3) The Company's periodic report on Form 10-Q for the quarterly period ended June 30, 2002 (the "Form 10-Q") fully complies with the requirements of Section 13 (a) or 15(d) of the Securities Exchange Act of 1934, as amended; and (4) The information contained in the Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of the Company. Dated: August 13, 2002 /s/ M. Michael Owens -------------------- ------------------------ M. Michael Owens