Competitive growth fabrics in stalactitic carbonate are not as widespread as commonly supposed. Most radial columnar crystals are attributed to the coalescence of a precursor crystallite mosaic comprised of syntaxial overgrowths. This secondary fabric is the consequence of carbonate precipitation from a thin water film. Competitive growth, however, is much rarer and arises from two contrasting environments: an influx of detritus interrupting carbonate precipitation, and cave flooding. Thick layers of impurities favour deposition of randomly oriented seed crystals on the growth surface. These result in competitive growth centres when the renewal of carbonate precipitation fails to have crystallographic allegience to the substrate. Competitive growth centres resulting in regularly spaced stellate arrays are favoured habits of fibrous aragonite. Competitive growth in calcite is more likely with conditions of cave flooding, when normal growth of syntaxial overgrowths is suppressed. This results in competitive growth between large terminations with planar faces.
Broughton, Paul L..
Environmental implications of competitive growth fabrics in stalactitic carbonate.
International Journal of Speleology,
Available at: http://scholarcommons.usf.edu/ijs/vol13/iss1/3