What it is:
This herb is theshell of Ostrea gigasThunb., or Ostrea talienwhanensis Crosse, or Ostrea rivularis Gould(family Ostreidae)which is produced incoastal areas. Whenthe flesh is taken off, the shell is washed clean,dried insunlight and used un-prepared or calcined.

Property:
Salty in flavour, slightly cold in property, acting on the liver and kidneychannels.

Effects:
Calmingthe liver and sup-pressing hyperac-tivity of the liver-yang, softening and dissolving hard massesand inducing as-tringency.

Used for:
1. Irritability,palpitation, insomniaand dizziness causedby hyperactivity of yang due to defi-ciency of yin. It isoften used togetherwith dragon's bone, achyranthes root, white peony root andred ochre, as in Tranquilizing Liver-wind Decoction(ZhenganXifeng Tang) ; in cases of stirring of endopathic wind of deficiency type withconvulsions of the extremities due to impairment of yin byfebrile diseases, it is often used with tortoise plas-tron, turtle shell, dried rehmannia rootand donkey- hide gelatin, as in Pulse Restoring Decoction of Three Shell Herbs(Sanjia Fumai Tang).

2. Scrofula and subcutaneous nodulesdue to accumulationof phlegm-fire. It is often used with thunberg fritillary bulb and scrophulariaroot viz. Scrofula-eliminating Pill(Xiaoluo Wan); it is also often used withred sage root , turtle shell and bugleweed in the treatment of hypo-chondriac massed(hepatolienomegaly).

3. Sweating due to debility, seminalemission,leukorrhagia,metrorrhagia and metrostaxis. For thetreatment of spontaneous sweatingand night sweat, itis often used with astragalus root , light wheat and ephedra root viz. Oyster Shell Powder ( Muli San) ; for seminal emission dueto deficiency of the kidney, it is often used together with flatstem milk-vetch seed, gordon euryale seed and lotus stamen, as in Golden Lock Pill forKeeping the Kidney Essence( Jinsuo Gujing Wan) ; to treat leukorrhagia, metrorrhagia and metrostaxis, it can be used with dragon'sbone, cuttle- bone and chinese yam. Besides, this herb has the action of neutralizing acidity so it can beused to relieve hyperhydrochloria.

Dosage and admi-nistration: 15-30g, crushed before usingand decocted earlierthan other herbs. For calming the liverand suppressing hyperactivity of theliver-yang, and softening and resol-ving hard masses, it should be used unprepared; for inducing astringency and neutralizing acidity, it should be used calcined.