Figure 19 shows a case where a zone of elongate blocky textured calcite occurs in the middle of a fibrous antitaxial calcite vein. Fibre shape is symmetric around the median line, except near the tips. Tapley Hill Formation, Opaminda Creek, Arkaroola, South Australia. Width of view 13 mm, crossed polars. Movie illustrating growth of an antitaxial fibrous vein, which typically contains a mineral different from those dominant in the wall rock.
Growth occurs on the two outer margins of the vein.
Note that not all crystals keep growing all throughout the growth history, but competition is usually not strong in antitaxial fibrous veins. Median zone in a dominantly fibrous antitaxial calcite vein. The median zone has an elongate blocky texture with growth mainly from the right to the left. Small wall rock inclusions and quartz crystals mark the edge of the median zone. Antitaxial growth took place after formation of the median zone, with fibres growing out of median zone grains.