珍(zhen)珠(zhu)巖(yan)礦(kuang)石中(zhong)(zhong)所(suo)含水分以二種(zhong)(zhong)(zhong)形態(tai)存在(zai)(zai)：一種(zhong)(zhong)(zhong)是(shi)(shi)附著在(zai)(zai)珍(zhen)珠(zhu)巖(yan)裂隙中(zhong)(zhong)的水，這(zhe)(zhe)種(zhong)(zhong)(zhong)水在(zai)(zai)高溫焙燒時，產(chan)生很大(da)的蒸汽壓力而使顆(ke)粒炸裂，增加產(chan)品(pin)的粉化宰，因(yin)而是(shi)(shi)不(bu)利的，因(yin)此(ci)在(zai)(zai)焙燒前必須排除。在(zai)(zai)較低(di)的溫度下(xia)即可(ke)將該種(zhong)(zhong)(zhong)水除掉。另一種(zhong)(zhong)(zhong)是(shi)(shi)在(zai)(zai)巖(yan)漿(jiang)噴出地(di)表后遇冷(leng)成礦(kuang)過(guo)程中(zhong)(zhong)的結合水。各(ge)地(di)珍(zhen)珠(zhu)巖(yan)的差(cha)熱曲線(xian)均無明顯的吸熱放熱峰，不(bu)存在(zai)(zai)品(pin)格(ge)破壞的問(wen)題，說明珍(zhen)珠(zhu)巖(yan)中(zhong)(zhong)不(bu)含結晶水。那么這(zhe)(zhe)種(zhong)(zhong)(zhong)水究竟是(shi)(shi)以一種(zhong)(zhong)(zhong)什么形態(tai)存在(zai)(zai)于(yu)玻璃質(zhi)中(zhong)(zhong)，目(mu)前尚無定論的意(yi)見(jian)。但是(shi)(shi)，認為它是(shi)(shi)引起礦(kuang)石膨脹的主要原因(yin)，這(zhe)(zhe)一點(dian)是(shi)(shi)一致的。因(yin)而研究這(zhe)(zhe)部分水與礦(kuang)石膨脹的關系(xi)是(shi)(shi)重要的。