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Science Frontiers ONLINE No. 66: Nov-Dec 1989 |
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Biogenic Minerals
We generally think of minerals as having been formed by purely inorganic processes. Only once, on p.000. where biogenic stalactites were described, have we persued the idea that minerals, including crystal forms, might be biogenic. We now have at hand a survey of biogenic minerals. It turns out that biogenic minerals are quite common - so common, in fact, that the Gaia concept is recalled, in which biological processes preside over much that happens upon this planet.
Here follows a sampler of some biogenic minerals:
- Much, if not all, travertine (calcite and/or aragonite) and silicious sinter (opal) are deposited through algal action.
- Much pyrite and marcasite in sedimentary rocks comes from bacterial sulfate reduction.
- Bacterial breakdown of oil produces organic complexes that dissolve, transport, and precipitate quartz. The reknowned Herkimer "diamonds" may be of biological origin.
- Living cells synthesize isometric crystals of magnetite.
- Mitochondria manufacture crystals of hydroxylapatite.
- Better known are the apatite in bones and teeth and the aragonite, calcite, or fluorite in the vestibular systems of vertebrates.
(Dietrich, R.V., and Chamberlain, Steven C.; "Are Cultured Pearls Mineral?" Rocks and Minerals, 64:386, September/October 1989. Cr. R. Calais)