1. Hydrogenous (Authigenous) sediment-Formed by the precipitation of chemicals in sea water (sometimes with bacteria) ex: manganese nodules, phosphorites, glauconite

2. 21 On the basis of riddling various nonmetal minerals and the application test of bentonite, zeolite, apatite, vermiculite, glauconite, expanded pearlite etc.

3. Moreover, thin-section preparations of sample aliquots showed that the glauconite grains contain biotite-relics, which might account for the elevated absolute ages.