Since antiquity, gold has been valued for its scarcity, beauty, and resistance to corrosion. Gold is the best known of all native elements and the most likely to be found in a metallic state (Pough 1991). It is the universal standard of value and the common medium of exchange in world commerce (Koschmann and Bergendahl 1968). Gold is almost everywhere considered to be the symbol of everything precious and of enduring value because of the effort required to extract it from nature, and because of its scarcity relative to other metals (Petralia 1996; Merchant 1998). Gold was known and highly valued by the earliest civilizations:

The basic structural building block of the biomarkers is the isoprene unit (Figure 1A). The end closer to the methyl branch is called the "head/' and the other end is the "tail." Compounds formed biosynthetically from isoprene units are called "isoprenoids." Two isoprene units joined head-to-tail (with minor modifications, such as hydrogenation of double bonds) form a monoterpane (Figure IB). Two monoterpanes (four isoprene units) linked together form a diterpane, whereas six isoprene units can be joined either to form a sterane or a triterpane, depending upon how the linking is accomplished.

The probing questions asked in biomineralization research are inevitably at the interface between two, three, or sometimes more disciplines. Observations are made at all length scales and involve bulk structures and interphases, macromolecules, cells and materials, and solid state transformations, and at the heart of this all, biomineralization is the product of complex cellular activity. It is therefore no surprise that the development of this field has closely tracked the development of analytical technology, literally over the last 300 years. Thus, a handbook devoted to methodology in the field of biomineralization is no doubt an invaluable resource. <...>

La Société Lafarge Ciments exploite depuis 1964 de grandes carrières dans le Beaujolais méridional, sur le territoire des communes de Belmont, Charnay et Saint-Jean-des-Vignes. Les travaux d’exploitation ont mis au jour des dépôts datés de l’Hettangien au Bathonien. Parmi ceux-ci, les sédiments toarciens, aaléniens et bajociens, particulièrement fossilifères, ont très tôt attiré l’attention des chercheurs amateurs et professionnels.