Dolomite in the Coorong Lagoon, South Australia Dolomite in the Coorong Lagoon, South Australia Coorong of South Australia, famous for modern precipitation of dolomite. The Coorong is an area of lagoons and ephemeral alkaline lakes behind modern beach barriers which are fed by seawater and also by continental groundwater from a seaward-flowing aquifer. Dolomite, magnesite, hydromagnesite, aragonite and high and low magnesian calcite are being precipitated in the lagoons and empheral lakes.
Dolomite occurs in the more landward lakes.
It is enriched in calcium, it lacks the full crystal superstructure when studied by X-ray diffraction and, thus, has been termed protodolomite . It occurs as a yoghurt-like pelletal mud which forms indurated crusts and flake breccias, algal laminates and polgonal desiccation cracks around the lake margins.