text: The growth rates of calthemite stalactite straws, stalagmites and flowstone etc., is very much dependent on the supply rate and continuity of the saturated leachate solution to the location of CaCO deposition. The concentration of atmospheric CO in contact with the leachate, also has a large influence on how quickly the CaCO can precipitate from the leachate. Evaporation of the leachate solution and ambient atmospheric temperature appears to have very minimal influence on the CaCO deposition rate.
  Calthemite straw stalactites precipitated (deposited) from hyperalkaline leachate have the potential to grow up to ≈200 times faster than normal cave speleothems precipitated from near neutral pH solution. One calthemite soda straw has been recorded as growing 2 mm per day over several consecutive days, when the leachate drip rate was a constant 11 minutes between drips. When the drip rate is more frequent than one drop per minute, there is no discernible deposition of CaCO at the tip of the stalactite (hence no growth) and the leachate solution falls to the ground where the CaCO is deposited to create a calthemite stalagmite. If the leachate supply to the stalactite straw's tip reduces to a level where the drip rate is greater than approximately 25 to 30 minutes between drops, there is a chance that the straw tip will calcify over and block up. New straw stalactites can often form next to a previously active, but now dry (dormant) straw, because the leachate has simply found an easier path through the micro cracks and voids in the concrete structure.
  Despite both being composed of Calcium Carbonate, Calthemite straws are on average just 40% the mass per unit length of speleothem straws of equivalent external diameter. This is due to the different chemistry involved in creating the straws. The calthemite straws have a thin wall thickness and a less-dense calcium carbonate structure compared to speleothem straws.
  Calthemite straws can vary in outside diameter as they grow in length. Changes in diameter can take a matter of days or weeks and are due to changes in drip rate over time. A slow dripping calthemite straw tends to be slightly larger in diameter than a fast-dripping straw.