Note: Intro -- Preface -- Reference -- Contents -- About the Authors -- 1 Introduction -- References -- 2 Thermodynamics, Geochemical Modeling and Related Considerations -- 2.1 A Synthesis of Thermodynamics for Geothermal Geochemistry -- 2.1.1 Gibbs Free Energy, Enthalpy, and Entropy -- 2.1.2 Standard State, Activity and Fugacity -- 2.1.3 The Equilibrium Constant -- 2.1.4 Thermodynamic Properties of Solids and Gases as a Function of T and P -- 2.1.5 Thermodynamic Properties of Aqueous Species as a Function of T and P -- 2.2 Supcrt92 -- 2.2.1 The Equilibrium Constant of the Dissolution Reaction of a Solid Solution -- 2.3 Geochemical Modeling -- 2.3.1 Equilibrium State Models -- 2.3.2 Multicomponent Chemical Geothermometry: A Reaction Path Model of Special Interest -- 2.3.3 Activity Coefficients in Relatively Dilute Solutions -- 2.3.4 Activity Coefficients in Concentrated Solutions -- References -- 3 The Reservoir Liquids -- 3.1 Calculation of the Chemical Composition of Reservoir Liquids -- 3.1.1 Calculation of Reservoir Liquid Chemistry for Liquid Enthalpy Wells -- 3.1.2 Calculation of Reservoir Liquid Chemistry for Excess Enthalpy Wells -- 3.1.3 Further Details on the Reconstruction of Reservoir Liquid Chemistry -- 3.1.4 Presentation of the Main Results of Speciation-Saturation Calculations and Approach Adopted for the Chemical Classification of Reservoir Liquids -- 3.2 The Reservoir Liquids from the Geothermal Systems in Iceland -- 3.2.1 Chemistry of the Reservoir Liquids from the High-Temperature Geothermal Systems in Iceland -- 3.2.2 Chemistry of the Reservoir Liquids from the Medium-Temperature Geothermal Systems in Iceland -- 3.3 The Reservoir Liquids from the Geothermal Systems in Northern and Central America -- 3.3.1 Dixie Valley -- 3.3.2 Long Valley -- 3.3.3 Coso -- 3.3.4 Valles -- 3.3.5 Salton Sea, Heber, and Cerro Prieto -- 3.3.6 Los Azufres. , 3.3.7 Berlin -- 3.3.8 Miravalles -- 3.3.9 Chemistry of the Reservoir Liquids from the Geothermal Systems in Northern and Central America -- 3.4 The Reservoir Liquids from the Geothermal Systems in Japan -- 3.4.1 Mori-Nigorikawa -- 3.4.2 Sumikawa -- 3.4.3 Uenotai-Wasabizawa -- 3.4.4 Onikobe -- 3.4.5 Oku-Aizu -- 3.4.6 Takigami -- 3.4.7 Oguni -- 3.4.8 Fushime -- 3.4.9 Chemistry of the Reservoir Liquids from the Geothermal Systems in Japan -- 3.5 The Reservoir Liquids from the Geothermal Systems in the Philippines -- 3.5.1 Bacon-Manito -- 3.5.2 Tongonan-Mahanagdong -- 3.5.3 Alto Peak -- 3.5.4 Palinpinon -- 3.5.5 Chemistry of the Reservoir Liquids from the Geothermal Systems in the Philippines -- 3.6 The Reservoir Liquids from the Geothermal Systems in New Zealand -- 3.6.1 Broadlands-Ohaaki -- 3.6.2 Kawerau -- 3.6.3 Mokai -- 3.6.4 Ngatamariki -- 3.6.5 Ngawha -- 3.6.6 Orakeikorako -- 3.6.7 Rotokawa -- 3.6.8 Waiotapu -- 3.6.9 Wairakei -- 3.6.10 Chemistry of the Reservoir Liquids from the New Zealand Geothermal Systems -- 3.7 The Reservoir Liquids from Miscellaneous Geothermal Systems -- 3.7.1 Yangbajing -- 3.7.2 Kizildere -- 3.7.3 Bagnore -- 3.7.4 Latera -- 3.7.5 Mofete -- 3.7.6 Ribeira Grande -- 3.7.7 Asal -- 3.7.8 Tendaho -- 3.7.9 Aluto-Langano -- 3.7.10 Olkaria -- 3.7.11 Chemistry of the Reservoir Liquids from Miscellaneous Geothermal Systems -- 3.8 Main Results of Speciation Calculations for the Reservoir Liquids and Implications -- 3.8.1 The pH Value -- 3.8.2 The Fraction of Undissociated SiO2(aq) -- 3.8.3 The Fractions of Free Na+, K+, Ca2+, and Mg2+ Ions -- 3.8.4 The Activity Coefficient of Undissociated SiO2(aq) -- 3.8.5 The Activity Coefficients of Free Na+, K+, Ca2+, and Mg2+ Ions -- 3.9 Final Considerations on the Reservoir Liquids -- References -- 4 The Hydrothermal Minerals -- 4.1 The Hydrothermal Alteration Suites and Their Zones. , 4.2 Feldspars -- 4.2.1 Main Characteristics of Feldspars -- 4.2.2 The Chemistry of Hydrothermal Feldspars -- 4.2.3 The Structural State and Degree of Ordering of Hydrothermal Alkali Feldspars -- 4.2.4 The Thermodynamic Properties of Endmember Alkali Feldspars -- 4.2.5 The Thermodynamic Properties of Variably Ordered Alkali Feldspars -- 4.3 White Micas -- 4.3.1 Main Characteristics of White Micas -- 4.3.2 The Activities of Muscovite, Celadonites, and Pyrophyllite in Hydrothermal White Micas -- 4.3.3 The Thermodynamic Properties of Muscovite -- 4.4 Chlorites -- 4.4.1 Main Characteristics of Chlorites -- 4.4.2 Crystal Chemistry of Hydrothermal and Diagenetic Chlorites -- 4.4.3 The Activities of Clinochlore and Chamosite in Hydrothermal and Diagenetic Chlorites -- 4.4.4 The Thermodynamic Properties of Chlorites -- 4.5 Epidotes -- 4.5.1 Main Characteristics and Nomenclature of the Minerals of the Epidote Group -- 4.5.2 The Crystal Chemistry of Epidote Solid Solutions -- 4.5.3 The Activities of Clinozoisite and Epidote Endmembers in Hydrothermal Epidote Solid Solutions -- 4.5.4 The Thermodynamic Properties of Epidotes -- 4.6 Prehnite -- 4.6.1 The Crystal Chemistry of Prehnite/Ferri-Prehnite Solid Solutions -- 4.6.2 The Endmember Activities in Hydrothermal Prehnite/Ferri-Prehnite Solid Solutions -- 4.6.3 The Thermodynamic Properties of Prehnite -- 4.7 Laumontite and Wairakite -- 4.7.1 Main Characteristics of Ca-Zeolites -- 4.7.2 Crystal Chemistry of Wairakite and Analcime -- 4.7.3 Crystal Chemistry of Laumontite -- 4.7.4 The Activity of Wairakite in Hydrothermal Wairakite/Analcime Solid Solutions -- 4.7.5 The Activity of Laumontite in Hydrothermal Laumontite/Alkali-Laumontite Solid Solutions -- 4.7.6 The Thermodynamic Properties of Wairakite and Laumontite -- 4.8 Garnets -- 4.8.1 Crystal Chemistry of Garnets. , 4.8.2 The Composition of Hydrothermal Garnet Solid Solutions -- 4.8.3 The Activity of Grossular and Andradite in the Hydrothermal Garnet Solid Solutions -- 4.8.4 The Thermodynamic Properties of Grossular and Andradite -- 4.9 Calcite -- 4.9.1 The Composition of Calcite-Rich Trigonal Carbonates from Active Geothermal Systems -- 4.9.2 The Carbonate Minerals Other Than Calcite from Active Geothermal Systems -- 4.9.3 The Thermodynamic Properties of Calcite -- 4.10 Quartz and Other Silica Minerals -- 4.10.1 The Activity of Endmember Quartz in Hydrothermal Quartz -- 4.10.2 The Thermodynamic Properties of the Quartz/Chalcedony Mechanical Mixture -- 4.11 Conclusive Considerations on Hydrothermal Minerals -- References -- 5 Traditional Water Geothermometers and fCO2 -Indicators -- 5.1 General Aspects of Geothermometers and fCO2 -Indicators -- 5.1.1 Basic Hypotheses of Geothermometry -- 5.1.2 Historical Overview -- 5.1.3 The Simple Form of Most Geothermometric Equations -- 5.2 The Silica Geothermometers -- 5.2.1 Constant-Enthalpy Relations Expressing the Solubility of Silica Minerals in Pure Water -- 5.2.2 Variable-Enthalpy Relations Expressing Quartz Solubility in Pure Water -- 5.2.3 Quartz Solubility in Salt Solutions -- 5.2.4 The Preferred Silica Geothermometers -- 5.2.5 The Silica Versus Enthalpy Plot -- 5.2.6 The Silica Mixing Model -- 5.2.7 The Silica Boiling Model -- 5.2.8 Silica Geothermometry for Wells with Excess Enthalpy (Excess Steam) Discharges -- 5.2.9 Relation Between Undissociated SiO2 and Aquifer Temperature for the Selected Reservoir Liquids -- 5.3 The Na-K Geothermometers -- 5.3.1 The Na-K Geothermometric Functions Proposed by Different Authors -- 5.3.2 Why so Many Empirical Na-K Geothermometers Were Derived in Previous Studies? -- 5.3.3 The Hydrothermal Minerals Controlling the Na-K Geothermometers. , 5.3.4 Conclusive Remarks on the Na-K Geothermometers -- 5.4 The Na-K-Ca Geothermometer -- 5.4.1 Formulation, Controlling Reactions, and Limitations/Problems of the Na-K-Ca Geothermometer -- 5.4.2 Performance of the Na-K-Ca Geothermometer for the Selected Reservoir Liquids -- 5.4.3 Na-Ca and K-Ca Geothermometers -- 5.4.4 The Hydrothermal Minerals Controlling the Na-Ca and K-Ca Geothermometers -- 5.4.5 Conclusive Remarks on the Na-K-Ca Geothermometer -- 5.5 The K-Ca fCO2 -Indicator -- 5.5.1 Relevant Reactions, Derivation, and Limitations of the K-Ca fCO2 -Indicator -- 5.5.2 Application of the K-Ca fCO2 -Indicator to the Selected Reservoir Liquids -- 5.6 The K-Mg and Na-Mg Geothermometers -- 5.6.1 Relevant Reactions, Derivation, and Limitations of the K-Mg and Na-Mg Geothermometers -- 5.6.2 Application of the K-Mg and Na-Mg Geothermometers to the Selected Reservoir Liquids -- 5.6.3 The Na-K-Mg0.5 Triangular Diagram -- 5.7 Other Ionic Solute Geothermometers -- 5.7.1 The Li-Based Geothermometers -- 5.7.2 The "Auxiliary Geothermometers" of Michard (1990) -- 5.7.3 The Ca-Mg and SO4-F Theoretical Geothermometers for Thermal Waters from Carbonate-Evaporite Reservoirs -- 5.8 The Influence of Ion Complexing on Geothermometers and fCO2 -Indicators -- 5.8.1 Theoretical Approach -- 5.8.2 Complexing in Hydrothermal Aqueous Solutions and Related Effects -- 5.8.3 The Theoretical Geoindicators of Chiodini et al. (1991) -- 5.8.4 The Lesson Learned and the Way Forward -- References -- 6 The Activity-Based Theoretical Na-K Geoindicators -- 6.1 The Log K of the Na-K Exchange Reactions Between Hydrothermal Alkali Feldspars -- 6.2 The Na+/K+ Log Activity Ratio of the Selected Reservoir Liquids -- 6.3 The Ordering Parameter Z of Hydrothermal Adularia in Hypothetical Equilibrium with the Selected Reservoir Liquids. , 6.4 The Theoretical Activity-Based Na-K Geothermometers Involving the Ordering Parameter of Adularia.