well-proportioned all original c. 1860's american antique victorian era white "alabama" (officially known as sylacauga) marble interior residential fireplace mantel keystone likely fabricated by the chicago marble mfg. co., chicago, il. the flush mount keystone contains prominently displayed delicately carved leafage. the keystone was salvaged from an italianate style chicago residence demolished long ago. multiple keystones were recently acquired from a form specializing in the restoration of chicago-area marble fireplace mantels. the chicago marble manufacturing company was fuounded in 1845, but not incorporated until 1872. at that time orin sherman was superintendent, and one hundred and twenty-five men were employed. chicago marble supplied the mantels, grates, etc, for the gardner house, matteson house, sherman house, grand pacific and tremont, prior to 1873, as well as for many dwelling houses during this time period. their yards were located at 713—15 wabash avenue, chicago, il. measures 8 x 3 x 10 1/2 inches.