Pumice hǎi fú shí · 海浮石

Pumex; also Costazia aculeata Canu et Bassler (Costaziae Os)

Nature and flavour. Salty and cold; Lung and Kidney systems.

Traditionally classed as clearing Lung heat and transforming phlegm, softening hardness and dissipating masses, and promoting urination. Recorded for cough and congested breathing with hot, thick phlegm, for old and stubborn phlegm accumulations, for scrofula and goitre, and for painful or difficult urination. Two quite different materials circulate under this name: volcanic pumice, a light porous rock, and the calcareous skeleton of a marine bryozoan. Classical texts describe both, and modern trade is not consistent about which one is being sold.