Jean-Baptiste Louis Romé de l’Isle

French mineralogist

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July 13, 2026

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Jean-Baptiste Louis Romé de l'Isle was a French mineralogist who confirmed Nicolaus Steno's findings in 1669. Steno's law, also known as the law of constancy of interfacial angles, states that the angles between corresponding faces on crystals of any given mineral species are constant and characteristic of that species. Romé de l'Isle further established that these angles are unique to each substance. This principle is fundamental in crystallography, as it allows for the identification of minerals based on their crystal structure, regardless of the crystal's size or origin.1

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Steno’s law
Romé de l’Isle, confirmed Steno’s findings and further noted that the angles are characteristic of the substance. A French crystallographer, René-Just Haüy, usually considered the father of crystallography, showed in 1774 that the known interfacial angles could be accounted for if the crystal were made…
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Romé de l’Isle, confirmed Steno’s findings and further noted that the angles are characteristic of the substance. A French crystallographer, René-Just Haüy, usually considered the father of crystallography, showed in 1774 that the known interfacial angles could be accounted for if the crystal were made…
Read More