Noktat Addagmar (LL5)
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cs 5.46 g
History: Two stones with a mass of 591 and 188 g, respectively (total known weight 779 g), were found by a Moroccan mineral collector (Sajid Ait Ben Chouk) near the caravansary of Noktat Addagmar after locals reported an abundance of “stones that recently fell from sky”, close to the track from Assa (Morocco) to Nouakchott (Mauritania).
Physical characteristics: The main mass is partly covered with a black fusion crust. The interior is greenish grey with slight rust haloes around metal. Porosity 8.2% based on alcohol absorption.
Petrography: (E. Gnos, MHNGE; B. Hofmann, NMBE, M. Eggimann, UBE/NMBE) Olivine Fa27.7 ± 0.6 (n = 27), pyroxene Fs23.1 ± 1.0 Wo1.6 ± 0.3. (n = 20). Shock stage is S2, some shock veins are visible, no weathering (W0). The mean diameter of chondrules is ~1 mm.
Cosmogenic radionuclides: (Patrick Weber, Particle Physics Group, Institute of Physics, University of Neuchâtel) Gamma-spectroscopy performed in December-January 2006 demonstrated the absence of short-lived radionuclides (no 22Na detected). The fall must have occurred at least several decades ago.
Classification: Ordinary chondrite (LL5), shock stage S2, no weathering (W0).
Type specimens: 22.4 g plus polished thin section at NMBE, main mass: Svend Buhl, Hamburg, Germany.
© Svend Buhl (Encyclopedia-of-Meteorites)
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Page update: 2016-05-07 22:48