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English: The three principal categories of fossils are: body fossils, trace fossils, and biogenic products. Biogenic products are objects produced by ancient organisms. Many paleontologists refer to these as trace fossils (= tracks, trails, burrows, borings, footprints, bitemarks, etc.). Examples of fossil biogenic products include eggs, amber (fossilized tree sap), coprolites (fossilized feces), and spider silk.

Fossilized tree sap, a.k.a. resin, is called amber. Resin that has not been completely altered to amber is called copal (“subfossilized tree sap”). The general term for such materials is resinite.

Copal ranges in age from several years old to ~33,000 years old. True amber ranges in age from a few million to hundreds of millions of years old - as far back as the Carboniferous.

Amber and copal vary in color, but are typically a rich, light- to dark-golden brown. Resinites are quite lightweight (but amber is more dense than copal), and show conchoidal fracture when broken. Copal often is, and has been, passed off as true amber.

Amber is valued as a gem material for its transparency and distinctive color. Amber and copal are also valued for the frequent presence of fossil inclusions - typically insects.

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Some references on amber & fossils in amber:

Poinar, G. & R. Poinar. 1994. The Quest for Life in Amber. Reading, Massachusetts. Addison-Wesley Publishing Company. 219 pp.

Dahlström, A., L. Brost & J. Leijonhufvud. 1996. The Amber Book. Tuscon, Arizona. Geoscience Press, Inc. 134 pp.

Grimaldi, D.A. 1996. Amber, Window to the Past. New York. American Museum of Natural History. 215 pp.

Ross, A. 1998. Amber. London. The Natural History Museum. 73 pp.

Poinar, G.O. & R. Milki. 2001. Lebanese Amber, the Oldest Insect Ecosystem in Fossilized Resin. Corvallis, Oregon. Oregon State University Press. 96 pp.

Geirnaert, E. 2002. L'Ambre, Miel de Fortune et Mémoire de Vie. Monistrol-sur-Loire, France. 176 pp. [in French]

Hong Youchong. 2002. Amber Insects of China. Beijing. Beijing Scientific Publishing House. 653 pp. 48 pls. [in Chinese]

Weitschat, W. & W. Wichard. 2002. Atlas of Plants and Animals in Baltic Amber. Munich. Dr. Friedrich Pfeil. 256 pp. [excellent resource! highly recommended!]

Selden, P. & J. Nudds. 2004. Baltic amber. pp. 131-141 in Evolution of Fossil Ecosystems. Chicago. University of Chicago Press.