The lava of the Oldoinyo Lengai
by Frank Möckel
The analytics of the last five decades are available in this link
Separate analyse 2004
Note: The analytic of my specimens (July 2004) are in the summary above
Separate analyse 2005 (Specimens from Chris Weber, Feb 05)
The thin section photo comes from Prof.J.Keller (University of Freiburg) who was 1988 together with Maurice Krafft at the Oldoinyo Lengai. A very remarkable expedition and the beginning of the modern investigation of the O.L. This micrograph photo shows the porphyric variety with Gregoryit and Nyerereit as phaeno crystals in a finest-granular matrix. The specific weight is apprx 2,0 g/cm³
Photo taken up in polarized light with crossed polarizers.
A comment from Frank explains the difficulties to analyse the Lengai-lava
In analytics of the Natrocarbonatit lava there is a fundamental problem. The Natrocarbonatit is chemically very unstable. That means, after a very short time (day, weeks) the changing processes (predominant hydratisation) already begins, which leads the mineralogical and petrochemical/geochemical reorganization. Today Natrocarbonatit specimens are transported in special containers and were examined immediately in laboratories. DAWSON published 1962 in the magazine NATURE the first analysis of the Natrocarbonatit lava of the Ol Doinyo Lengai. This lava sample was not fresh!!! H2O - concentrations of over 8% prove that. Fresh Natrocarbonatit has maximally 0.56% water content (CELLAR, KRAFFT 1988). Therefore I am not able to analyze cost-intensively unfresh Natrocarbonatit specimens.
Thin section photo of Natrocarbonatit in simple (linear) polarized light. Lava assay by 1988, Prof. Jörg Keller,
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