Antique Seth Thomas Adamantine "Petrel" Mantle Clock. Has the stylized "Egyptian" lion holding a bar on each side. Measures 16"x7"x12". Weight 9 pds. With two keys and original pendulum. Minor wear, missing small leaf adamantine veneer to front. Working, not tested for timekeeping. PROVENANCE: A Private Charleston SC Estate. In the 1860s, French clocks in slate, onyx or marble cases became popular in the United States. These cases were expensive, so the American clock manufacturers produced similar looking cases made of iron or wood. These clocks have become known to collectors as "Black Mantel Clocks", and were popular from 1880 to 1931. Seth Thomas made clocks in marble cases for a short time, from 1887 to ca. 1895. They also made clocks in iron cases finished in black enamel, from 1892 to ca. 1895. Seth Thomas is well known for their "Adamantine" black mantel clocks, which were made starting in 1882. Adamantine is a celluloid veneer, glued to the wood case. Adamantine veneer was made in black and white, and in colored patterns such as wood grain, onyx and marble. Adamantine veneer was developed by the Celluloid Manufacturing Company of New York City, and was covered by U.S. Patent number 232,037, dated September 7, 1880. Seth Thomas Clock Company purchased the right to use the Adamantine veneer in 1881.