New data on selected Ivory Coast tektites
Fourteen Ivory Coast tektites exhibit a range of bulk indices of refraction of 1.5156 to 1.5217 ± 0.0004 and of bulk specific gravities of 2.428 to 2.502 ±0.005. Seven of these Ivory Coast (IVC) tektites were analyzed for major and minor element content. Compared to tektites from other strewn fields, their SiO 2 content is low (67.2–69.1 %), A1 2 O 3 relatively high (15.8–16.8 %), and total iron relatively high but with a more restricted range (6.3–6.8 % as FeO). Their lime content is low (0.71–1.35%) compared to Australasian tektites but their MgO CaO "> MgOCaO ratio (about 3.1) is unusually high. All other tektite groups have Na 2 O K 2 O "> Na2OK2O ratios less than unity, but the Na 2 O K 2 O "> Na2OK2O ratio of the IVC tektites is slightly greater than unity. Their K Rb "> KRb ratios range from 200 to 256 and average 227, which is higher than those determined for Australasian tektites, but similar to some obtained for moldavites. The Li content (41–48 ppm) is about the same as that of the Australasian tektites, but the Cs and Rb are lower, being 1.9 to 2.9 and 57 to 86 ppm, respectively. The IVC tektites are high in Cr (260–375 ppm), Co (19–25 ppm) and Ni (101–167 ppm), and particularly in Pb (<10–18 ppm ), Cu (13–21 ppm) and Ga (14–23 ppm). The high Cr Ni "> CrNi ratios of the IVC tektites (range 2–3.6) are similar to those found for australites, philippinites and thailandites, but not the javanites and indochinites. Evaluation of these and other reported data show that compositional similarities between the IVC tektites and green or black Bosumtwi Crater glasses strongly support the hypothesis of a common impact origin—i.e. the Bosumtwi Crater site. Comparison of the IVC tektite composition with those of returned lunar materials (gabbros, basalts, breccia and soils) do not support a lunar origin for the Ivory Coast tektites.