Stalactite a cave it will drip down. When the solution comes into contact with air the chemical reaction that created it is reversed and particles of calcium carbonate are deposited. The reversed reaction is: An average growth rate is a year. The quickest growing stalactites are those formed by a constant supply of slow dripping water rich in calcium carbonate (CaCO) and carbon dioxide (CO), which can grow at per year. The drip rate must be slow enough to allow the CO to degas from the solution into the cave atmosphere, resulting in deposition of CaCO on the stalactite. Too fast
Sodium carbonate The sodium carbonate test (not to be confused with sodium carbonate extract test) is used to distinguish between some common metal ions, which are precipitated as their respective carbonates. The test can distinguish between copper (Cu), iron (Fe), and calcium (Ca), zinc (Zn) or lead (Pb). Sodium carbonate solution is added to the salt of the metal. A blue precipitate indicates Cu ion. A dirty green precipitate indicates Fe ion. A yellow-brown precipitate indicates Fe ion. A white precipitate indicates Ca, Zn, or Pb ion. The compounds formed are, respectively, copper(II) carbonate, iron(II) carbonate, iron(III) oxide, calcium carbonate, zinc carbonate,