tuffschist:bijoux-et-mineraux:Rare Cretaceous Gastropod epigenized in Dendritic Agate - Betul, India

tuffschist:bijoux-et-mineraux:Rare Cretaceous Gastropod epigenized in Dendritic Agate - Betul, India epigenesis : 1. Change in mineral character of a rock as a result of external influences acting at or near the earth’s surface; e.g., mineral replacement during metamorphism. 2. The changes at low temperatures and pressures that affect sedimentary rocks after their compaction, exclusive of weathering and metamorphism; e.g., dolomitization after deposition. The term is equivalent to late diagenesis.Definition from Bates, Robert L., and Julia A Jackson (1984). Dictionary of Geological Terms, Third Edition, Prepared by the American Geological Instititute. -- source link

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