Hollardops Trilobite

Hollardops Middle Devonian Ofaten, Morocco   Specimen approx. size: 2.5" x 1.5" Matrix approx. size: 4" x 3" x 2.5"   This specimen has excellent eye facet preservation and amazing detail throughout the body. It has been prepared so that it flies above the limestone on a pillar of stone.   What is striking about this trilobite is the interesting bicolored preservation. At some point during diagenesis the chemistry of the minerals changed resulting in the light coloration to one half of the specimen, changing the color from the typical dark coloration to almost white. Diagenesis is the process that describes physical and chemical changes in sediments brought about after their deposition but before their final lithification (conversion to rock). Because most sediments contain a mixture of minerals in which not all the minerals are in chemical equilibrium with each other, changes in interstitial water composition, temperature, or both will usually lead to chemical changes in at least one