| Dhofar 535 CH ungr |
|
Many stones weighing a total of 204 g were found in the Dhofar region of Oman. Mineralogy
and classification (M. Ivanova, Vernad; L. Taylor, UTenn): the meteorite consists of chondrules,
0.08–3.2 mm in diameter, (0.86 mm in average) of different types, PO, POP, BO, RP, CC, and
their fragments embedded in a fine-grained matrix. Chondrule/matrix ratio is 1.1. Olivine and
low-Ca pyroxene have large compositional ranges: olivine has Fa1–50, CaO 0.2 wt%; Al2O3
0.06 wt%, Cr2O3 0.09 wt%, PMD of Fa 42%; low-Ca pyroxene is Wo2– 3.5En53–95;
chondrules contain glassy mesostasis. Accessory minerals include: pigeonite, chromite,
troilite, rare hydroxides, and rare FeNi metal (Ni 5 wt%; Co 0.4 wt%). Thermoluminescence
studies (A. I. Ivliev, Vernad) indicate petrologic type 3.2/3.3. The meteorite is heavily
weathered, and some silicates are altered. Weathering grade is W5; shock stage is S1.
Based on the very low abundance of FeNi metal and hydroxides, Dho 535 could belong to
either the LL or R chondrite groups but with very abundant matrix. The average size of
chondrules is consistent with LL chondrites. A histogram showing the distribution of olivine is
similar to unequilibrated ordinary chondrites. FeNi metal is mostly kamacite, typical for H
chondrites and unusual for R chondrites. Sulfide assemblages and chromite chemistry are
also unusual for R chondrites. The absence of refractory objects and olivine chemistry
distinguish Dho 535 from C3 chondrites. Oxygen isotope composition (R. N. Clayton, UChi):
δ18O = +8.56‰; δ17O = +4.96‰, ∆17Ο = 4.51‰ is unusual for any chondrite type.
Specimens: type specimen of 46.8 g and thin section, Vernad; main mass with anonymous
finder.
and classification (M. Ivanova, Vernad; L. Taylor, UTenn): the meteorite consists of chondrules,
0.08–3.2 mm in diameter, (0.86 mm in average) of different types, PO, POP, BO, RP, CC, and
their fragments embedded in a fine-grained matrix. Chondrule/matrix ratio is 1.1. Olivine and
low-Ca pyroxene have large compositional ranges: olivine has Fa1–50, CaO 0.2 wt%; Al2O3
0.06 wt%, Cr2O3 0.09 wt%, PMD of Fa 42%; low-Ca pyroxene is Wo2– 3.5En53–95;
chondrules contain glassy mesostasis. Accessory minerals include: pigeonite, chromite,
troilite, rare hydroxides, and rare FeNi metal (Ni 5 wt%; Co 0.4 wt%). Thermoluminescence
studies (A. I. Ivliev, Vernad) indicate petrologic type 3.2/3.3. The meteorite is heavily
weathered, and some silicates are altered. Weathering grade is W5; shock stage is S1.
Based on the very low abundance of FeNi metal and hydroxides, Dho 535 could belong to
either the LL or R chondrite groups but with very abundant matrix. The average size of
chondrules is consistent with LL chondrites. A histogram showing the distribution of olivine is
similar to unequilibrated ordinary chondrites. FeNi metal is mostly kamacite, typical for H
chondrites and unusual for R chondrites. Sulfide assemblages and chromite chemistry are
also unusual for R chondrites. The absence of refractory objects and olivine chemistry
distinguish Dho 535 from C3 chondrites. Oxygen isotope composition (R. N. Clayton, UChi):
δ18O = +8.56‰; δ17O = +4.96‰, ∆17Ο = 4.51‰ is unusual for any chondrite type.
Specimens: type specimen of 46.8 g and thin section, Vernad; main mass with anonymous
finder.
Image dho535-3
Image dho535-4
Image dho535-2
Image dho535-1
Copyright 2008
Copyright 2008
Copyright 2008
Copyright 2008