Émile Bertrand (1844–1909) was a French

mineralogist Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical mineralogy, optical) properties of minerals and mineralized artifact (archaeology), artifacts. Specific s ...

, in honour of whom

bertrandite Bertrandite is a beryllium sorosilicate hydroxide mineral with composition: Be4Si2O7(OH)2. Bertrandite is a colorless to pale yellow orthorhombic mineral with a hardness of 6–7. It is commonly found in beryllium rich pegmatites and is in part ...

was named by

Alexis Damour Augustin Alexis Damour (19 July 1808, in Paris – 22 September 1902, in Paris) was a French mineralogist who was also interested in prehistory. Biography In 1827 he studied under Alexandre Brongniart at the Muséum d'Histoire Naturelle in ...

. He also gave his name to the ''Bertrand lens'' or phase telescope. He studied at the Ecole des Mines in

Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...

and was a co-founder of the . He wrote a book on the application of

microscopy Microscopy is the technical field of using microscopes to view subjects too small to be seen with the naked eye (objects that are not within the resolution range of the normal eye). There are three well-known branches of microscopy: optical mic ...

to mineralogical studies, "''De l'Application du microscope à l'étude de la minéralogie''" (1878); published a translation of

Ernst Mach Ernst Waldfried Josef Wenzel Mach ( ; ; 18 February 1838 – 19 February 1916) was an Austrian physicist and philosopher, who contributed to the understanding of the physics of shock waves. The ratio of the speed of a flow or object to that of ...

's work on the history of mechanics, "''La mécanique: exposé historique et critique de son développement''" (1904); and is credited with the design of a

refractometer A refractometer is a laboratory or field device for the measurement of an Refractive index, index of refraction (refractometry). The index of refraction is calculated from the observed refraction angle using Snell's law. For mixtures, the index ...

.Dictionary of Gems and Gemology
by Mohsen Manutchehr-Danai

References

1844 births 1909 deaths French mineralogists {{geologist-stub