noun

1. a soft, claylike, orthorhombic mineral, Mg(SiO)(OH)·6HO, used to make tobacco pipes and other heat-resistant items; hydrous magnesium silicate; sepiolite
2. a pipe with a bowl made of this

Etymology: Ger, lit., sea foam (< meer, sea + schaum, foam), transl. of ML spuma maris, orig. used of coral, calque of Gr halos hachnē: name transferred in 18th-c. Ger to a variety of lithomarge