What is the material of wenwan silk?

According to Zhihu's inquiry, Wenwanchou usually refers to a kind of culture and art called "German Fossil". This kind of artworks has certain collection and investment value, and is mainly produced in Dehua County, Fujian Province. German fossil is a kind of natural stone, which is known as "a treasure in stone" because of its hard, delicate, colorful and beautiful texture. German fossils contain high concentration of hydrogen sulfide, and its special material composition and chemical properties make it have a certain smell. Some people will retain the natural smell of stones when making literary and artistic works, which forms the so-called "literary stink".