Mineralogical Magazine; April 2004; v. 68; no. 2;
p. 369-394; DOI: 10.1180/0026461046820193
© Mineralogical Society of Great Britain and Ireland
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FIG. 7. Pt-Ir-Cl-K-containing silica. (a) MNHN. Al-Si-Fe-Mg-Ca-O fragment (light grey) encrusted with zoned silica layers (dark grey; Table 4, col. 1). Pol. sect. SEM(BS). 160 µm. (b) MNHM Enlargement of part of Fig. 7a. Zones of lighter grey shades correspond to increased concentrations of Pt, Ir and Fe (Table 4, col. 2). SEM(BS). 25 µm. (c) MNHM. Silica grain (dark grey; Table 4, col. 3) showing lighter central spots (Table 4, col. 4), corresponding to increased concentrations of Pt. Light grey inclusions: chromite. Irite is concentrated along the right border (white). Pol. sect. SEM(BS). 140 µm. (d) ENSM. Al-Fe- and Mg-Ca-silicate particles (smooth grey) cemented by fluidal Pt-Fe-Cl-K-containing silica (dark grey; Table 3, col. 5). Pol. sect. SEM(BS). 260 µm. (e) Enlargement of the right hand side of Fig. 6b. Pt-Ir-containing silica. Pol. sect. SEM(BS). 50 µm. (f) Enlargement of a portion of Fig. 7e showing concentric zones of Pt-Ir-enriched silica. SEM(BS). 12 µm. (Table 3, cols 6 and 7).
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