The invention is a matrix for preparing a tissue sample made of saline, albumin, gelatin, formaldehyde, a detergent, sucrose, lysine, and glutaraldehyde. The matrix is formed by first preparing a solution of saline, albumin, and gelatin, and then mixing the solution with formaldehyde, a detergent, and sucrose. Immediately prior to fixation of the tissue, a separately prepared lysine-glutaraldehyde mixture is added. The resulting matrix will harden rapidly and may be used to fix tissue samples for histological processing. In particular, a layer of the matrix may be poured into a mold and allowed to harden to form a base. One or more tissue samples may then be pinned to the base of matrix in the mold and then covered with the matrix. Once the matrix hardens, the pins and mold may be removed, and the tissue sample or samples embedded in the matrix are ready for sectioning.