05227 - Beautiful Pyritized 0.86 Inch Phylloceras Lower Cretaceous Ammonites Neltneria Exallaspis

Exallaspis

Coexistence of native Fe and Fe-Ni alloys

Ypresian and “Euclastes group” elements

Brochantitie forms mainly in exposed areas where weathering prevents accumulation copper ions and enhancement in the acidity of water films

See also Kumar and Loyal 1987

05227 - Beautiful Pyritized 0.86 Inch Phylloceras Lower Cretaceous Ammonites Neltneria ExallaspisSpecimen of extreme quality. His suture lines are wonderfully well detailed. It is naturally pyritized. It has undergone a taphonomic process of permineralization in Iron Sulfide (Pyrite). Permineralization is a process of fossilization in which mineral deposits form internal casts of organisms.