Si-associated goethite in hydrothermal sediments of the Atlantis II and Thetis Deeps, Red Sea

Nurit Taitel-Goldman, Christian Bender Koch, Arieh Singer

Research output: Contribution to journalArticlepeer-review


The properties of Si-associated goethite from sediments in the Atlantis II and Thetis Deeps in the Red Sea have been investigated in order to determine the effect of Si on the mineral. Two types of morphologies dominate in most samples: multi-domain crystallites, probably due to elevated Na concentration in the initial brine from which the mineral had crystallized, and mono-domain, acicular crystals. Goethite crystals with elevated Si/Fe elemental ratios are usually smaller and poorly crystalline, exhibiting numerous crystal defects, whereas larger crystals with higher crystallinity have lower Si/Fe elemental ratios. The higher Si/Fe ratios in Atlantis II Deep goethites and the lower ratio in Thetis Deep goethites probably reflect the levels of Si concentration in the hydrothermal fluids from which goethite precipitated. At relatively low Si/Fe ratios, the major effect of Si is to retard growth of the crystallites, but only a small number of defects are formed. At high Si/Fe ratios the defect concentration affects the properties of the crystals, as observed with Mössbauer spectroscopy. The Si association with goethite affects crystallinity and crystal size as indicated by X-ray diffraction, infrared spectroscopy and high-resolution transmission electron microscopy.

Original languageEnglish
Pages (from-to)115-129
Number of pages15
JournalClays and Clay Minerals
Issue number1
StatePublished - Feb 2004


  • Analytical electron microscopy
  • Atlantis II Deep
  • Crystal properties
  • High-resolution transmission electron microscopy
  • Hydrothermal sediments
  • Infrared spectroscopy
  • Mössbauer spectroscopy
  • Si-associated goethite
  • Thetis Deep
  • X-ray diffraction


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