Shells and minerals, solid in quality with active constituents difficult to extract, should be broken up and decocted first for about 20 minutes before adding other drugs, e.g. Guiban ( Plasstrum Testudinis ), Biejia ( Carapax Trionycis), Shijueming ( Concha Haliotidis), fresh Mull ( Concha Ostreae), Daizheshi ( Ochra Haematitum ), Longgu ( OsDraconis), Shigao ( Gypsum Fibrosum), and Cishi (Magnetiturn), etc. Some drugs with much sand and mud, such as Zaoxintu ( baked earth), Nuodaogen (Radix  Oryzae Glutinoae), and some drugs light but in large dosage, such as Lugen (Rhizoma Phragmitis ), Xiakucao ( Spica Prunellae), should all be decocted first to get their clarifying juice, in which other drugs are decocted rather than in water. It should be noted in the prescription.