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A Differential Scanning Calorimetry Evaluation of Quartz Status in Geogenic and Pedogenic Environments
Author(s) -
Bartenfelder D. C.,
Karathanasis A. D.
Publication year - 1989
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1989.03615995005300030055x
Subject(s) - quartz , pedogenesis , differential scanning calorimetry , igneous rock , mineralogy , weathering , metamorphic rock , geology , sedimentary rock , activation energy , geochemistry , chemistry , soil water , soil science , thermodynamics , paleontology , physics , organic chemistry
Twelve quartz samples of geologic and soil materials were investigated by differential scanning calorimetry (DSC) to evaluate the effects of origin, crystal deformation, depositional environments, and weathering conditions on the α‐β inversion temperature, enthalpy of inversion (Δ H ), and activation energy ( E a ) characteristics of quartz. The 50‐ to 20‐µm particle size fraction was found to be the most suitable for thermal and x‐ray analyses. There was little variation (<2 °C) in the inversion temperature of quartz in the studied samples, which appeared to depend on apparatus and conditions. The Δ H of inversion demonstrated more sensitivity than inversion temperature, to structural substitutions or deformations, with values ranging from 1.70 to 5.86 J/g. The igneous and metamorphic samples had the highest, whereas the soil samples had the lowest Δ H . The use of apparent activation energies ( E a ) showed the most promise in distinguishing the materials with respect to quartz origin, environment of deposition and extent of weathering. Activation energies were higher in igneous than metamorphic materials, decreased with age of deposit in the sedimentary materials, and generally decreased with extensive weathering of soil materials with some dependence on material type. The data suggest that E a values may represent the integrated effect of geothermal, geogenic and pedogenic environments on the quartz structure.