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Haüy, René Just

crystal rhombs cleavage french

[hahwee] (1743–1822) French mineralogist: founder of crystallography.

Although Haüy’s father was an impoverished clothworker, the boy’s interest in church music secured an education for himself through the help of the church. He became a priest, and professor of mineralogy in Paris, in 1802 had shown in 1670 that the angle between corresponding faces in the crystals of one substance is constant (irrespective of crystal size or habit), but he had not studied crystal cleavage proposed that a crystal must be built of identical particles piled regularly ‘like shot’ or, as phrased it, ‘in rank and file’. Haüy developed these ideas; he accidentally broke a calcite crystal and noted that the pieces were all rhombodedral, which implied a common underlying structure. He showed in 1784 that the faces of a calcite crystal might be formed by stacking cleavage rhombs regularly, if the rhombs are assumed to be so small that the face appears smooth . Similar principles would lead to other crystal shapes built from appropriate structural units. In developed form, this is still the modern view.

As a priest, Haüy was in some danger in the French Revolution, but friends protected him and Napoleon (the first world leader with a scientific or engineering training) appointed him to a post and directed him to write a textbook of physics for general use.

Habash, George (1925–) - PERSONAL HISTORY, INFLUENCES AND CONTRIBUTIONS, BIOGRAPHICAL HIGHLIGHTS, PERSONAL CHRONOLOGY:, After 1967, CONTEMPORARIES [next] [back] Hückel, Erich

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