Lei de Steno
Origem: Wikipédia, a enciclopédia livre.
A Lei de Steno diz que, os cristais em sua grande maioria, são malformados. As condições de crescimento fazem com que os cristais se desenvolvam sem simetria.
Despite a relatively brief scientific career, Nicholas Steno's work on the formation of rock layers and the fossils they contain was crucial to the development of modern geology. The principles he stated continue to be used today by geologists and paleontologists.
Steno was born as Niels Stensen, but he is better known by the Latinized forms of his name, Nicholas Stenonis or Nicholas Steno. A native of Copenhagen, Denmark, Steno left Denmark in 1660 to study medicine at the leading center for medical education of his time, the University of Leiden in the Netherlands. After brief stints in Paris and Montpelier, he moved to Florence, Italy in 1665. His studies in anatomy attracted the attention of the Grand Duke of Tuscany, Ferdinand II, who was also a patron of the sciences. Duke Ferdinand appointed Steno to a hospital post that left him ample time for his research. Steno was also elected to the Accademia del Cimento (Experimental Academy), a body of researchers inspired by Galileo's experimental and mathematical approach to science.
Steno's anatomical studies focused at first on the muscular system and the nature of muscle contraction -- for example, he used geometry to show that a contracting muscle changes its shape but not its volume. However, in October 1666, two fishermen caught a huge shark near the town of Livorno, and Duke Ferdinand ordered its head to be sent to Steno. Steno dissected it and published his findings in 1667. The figure at right shows the figure published by Steno of the shark's head and teeth (click on it to view a larger version). While examining the teeth of the shark, Steno was struck by their resemblance to certain stony objects, called glossopetrae or "tongue stones," that were found in certain rocks. Ancient authorities, such as the Roman author Pliny the Elder, had suggested that these stones fell from the sky or from the moon. Others were of the opinion, also going back to ancient times, that fossils naturally grew in the rocks. Steno's contemporary Athanasius Kircher, for example, attributed fossils to a "lapidifying virtue diffused through the whole body of the geocosm." Steno, however, argued that glossopetrae looked like shark teeth because they were shark teeth, that had come from the mouths of once-living sharks, and come to be buried in mud or sand that was now dry land. There were differences in composition between glossopetrae and living sharks' teeth, but Steno used the "corpuscular theory of matter", a forerunner of atomic theory, to argue that fossils could be altered in chemical composition without changing their form.
