POLISHED CHINESE WRITING ROCK

Chinese writing rock, also known as Chinese writing stone, is a lapidary material that is named for its resemblance to Chinese characters. It's composition is porphyritic basalt, or porphyry, that features groups of plagioclase feldspar crystals in a black basalt matrix. This stone is found in Auburn, California, where it was discovered while cutting a highway. The area is now inaccessible, and only a limited amount of the material was recovered before the highway was finished.