>Does anyone know if geologists/mineralogists have looked into this for stal=
>agtites/helictites? Could helictites be more "salty" than normal soda stra=
>ws?
>https://www.sciencenews.org/article/ripple-effect
>Jen
This "ripple" pattern is observed only on icicles (and stalactites?)
that are growing via deposition on the exterior surfaces. Soda-straws and
helictites are fed from internal canals (water-drop diameter in straws;
capillary size in helictites), and can't be expected to show effects that
develop in an external film. Helictites are typically irregularly crooked
(thought to be the result of crystal-growth forces), and are not made of
regularly-spaced annular rings. In helictites, the nearest thing I have
seen to that is the rare "beaded" pattern in which some aragonite
helictites are composed of a string of repeating growths of conical clumps
of diverging crystals (e.g., in Silent Splendor and Breezeway Cave at
Manitou, Colorado). As far as I know, the mechanism that causes beaded
helictites has never been explained, so I can't rule out that development
of their structure may involve subtle chemical effects. In general,
however, helictites and stalactites are often found together, sharing the
same water source, and whether a helictite or stalactite grows from a
given point seems to depend on whether the source flow is enough to form a
hanging drop at the tip (which will make the resulting form a stalactite).
--Donald
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