Chert: Modern Inorganic Deposition in a Carbonate-Precipitating Locality

Abstract
Chert is precipitating as gelatinous opal-cristobalite in lakes associated with the Coorong Lagoon of South Australia. Dolomite, magnesite, and magnesian calcite are also being deposited. High p H (9.5 to 10.2) causes dissolution of detrital silicates; lowering of p H (7.0 to 6.5) and drying of the lakes cause precipitation of chert.