High pH (~9) and alkalinity (~1000 mg/L) make Pyramid Lake a favorable location for calcium carbonate nucleation and precipitation.
Because of the high Mg2+:Ca2+ ratio in Pyramid Lake, calcite growth is inhibited and aragonite growth is favored in open waters.
The solution variable directly controlling supersaturation is denoted as 
, which is the ratio of the aragonite
ion activity product (
Ca2+
CO32-) to the solubility product (KAragonite).
Pyramid Lake is usually supersaturated
( >1) with respect to aragonite but natural inhibitors such as phosphate and dissolved organic acids suppress
nucleation until supersaturation reaches levels as high as = 20.
In natural waters the nucleation of a supersaturated mineral phases is enhanced by the presence of solid substrates, such as the mineral itself or suspended particulates. This process is known as "heterogeneous nucleation" nucleation" where no nucleation substrate is available - a situation that is unlikely in natural systems.
