Geothermal in Thailand, manifest as hot springs, have been collected for chemical and physical analysis studies since 1946.
There are 116 hot spring manifestations in northern, western, central and southern Thailand. Hot springs are of nonvolcanic
origin as inferred from isotopic relationship between δD and δ18O. Hot springs, surface temperatures range 40-100
°C, is clear, colorless with white algae, white-yellow and red scar of calcium carbonate, sulphur and iron disseminate on
soil and rocks. Chemical analysis discloses that hot springs yield pH 6.4-9.5, total dissolve solid 130-24,800 ppm, alkalinity
of bicarbonate 47-1,079 ppm and fluoride 0.055-20.4 ppm. Nine hot spring areas are saline. Geothermometer calculation
using silica, calcium and potassium contents denotes subsurface temperature of the five highest reservoir temperature
ranges 180-210 °C.