T_(HE) structure of aqueous and metal bearing solution, if observed dynamically by in situ spectrometer atelevated temperatures and pressures, will show new information on the kinetic mechanism of ore-formingfluids and water/mineral interactions. 1 Water and NaCl aqueous solutions The nature of water and NaCl·H_2O solutions has been examined in a temperature range from 25 to850℃ and pressure from 1.33×10~5 to 1.33×10~6 Pa by using hydrothermal diamond anvil cell (HDAC)and in situ FT-IR spectroscopy (an infra-red microscope: Bio-Rad, UMA, 500). The phase transitionsof NaCl-H_2O solutions can be observed by using an optical microscopy connected with HDAC, and at thesame time the infra-red spectra of NaCl-H_2O binary system at any fixed physical chemical conditions canbe tested. T_ (HE) structure of aqueous and metal bearing solution, if apparently dynamically by in situ spectrometer atelevated temperatures and pressures, will show new information on the kinetic mechanism of ore-forming fluid and water / mineral interactions. 1 Water and NaCl aqueous solutions The nature of water and NaCl · H_2O solutions has been examined in a temperature range from 25 to 850 ° C and pressure from 1.33 × 10 ~ 5 to 1.33 × 10 ~ 6 Pa by using hydrothermal diamond anvil cell (HDAC) and in situ FT-IR spectroscopy ( an infra-red microscope: Bio-Rad, UMA, 500). The phase transitions of NaCl-H 2 O solutions can be observed by using an optical microscopy connected with HDAC, and at the time of the infra-red spectra of NaCl-H 2 O binary system at any fixed physical chemical conditions canbe tested.