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Table 3 Granodiorite mineral composition

From: Thermally driven fracture aperture variation in naturally fractured granites

Phase Mineral Formula \(f_{n}{^\text{a}}\) \(\chi_{\text{Si},n}{^\text{b}}\) \(\rho_n{^\text{b}}\) (\(\text {kg}\,\text {m}^{-3}\))
Quartz Quartz \(\text {SiO}_2\) 0.300 0.467 2648
Plagioclase Albite \(\text {NaAlSi}_3\text {O}_8\) 0.150 0.201 2620
Anorthite \(\text {CaAl}_2\text {Si}_2\text {O}_8\) 0.150 0.321 2730
K-feldspar Microcline feldspar \(\text {KAlSi}_3\text {O}_8\) 0.125 0.302 2620
Orthoclase \(\text {KAlSi}_3\text {O}_8\) 0.125 0.302 2560
Biotite Annite \(\text {KFe}_3\text {AlSi}_3\text {O}_{{10}}(\text {OH})_2\) 0.150 0.164 3260
  1. Mineral composition considered for the calculation of fracture aperture changes, due to chemical mineral dissolution, where \({f}_n\) is the mineral volume fraction of the n-th mineral, \(\chi _{\text{Si},n}\) is the mass fraction of Si per mol of mineral n, and \(\rho _n\) is the density of mineral n
  2. aGrimsel granodiorite: \(\sim\)  30% quartz, \(\sim\) 30% plagioclase, \(\sim\) 25% K-feldspar, \(\sim\) 15% biotite, and minor amounts of white mica and chlorite (Stalder 1964; Schaltegger 1989)
  3. bSource: SciFinder: Database of chemicals (2019)