Auguste Michel-Lévy (7 August 184427 September 1911) was a French

geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, alth ...

. He was born in

Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S ...

Biography

He became inspector-general of mines, and director of the Geological Survey of France. He was distinguished for his researches on extrusive rocks and their microscopic structure and origins. He employed the polarizing microscope early on for the identification of minerals.Auguste MICHEL-LEVY (1844-1911)
Annales.org In his many contributions to scientific journals he described the

granulite Granulites are a class of high-grade metamorphic rocks of the granulite facies that have experienced high-temperature and moderate-pressure metamorphism. They are medium to coarse–grained and mainly composed of feldspars sometimes associate ...

group, and dealt with pegmatites, variolites, eurites, the

ophites The Ophites, also called Ophians (Greek Ὀφιανοί ''Ophianoi'', from ὄφις ''ophis'' "snake"), were a Christian Gnostic sect depicted by Hippolytus of Rome (170–235) in a lost work, the ''Syntagma'' ("arrangement"). It is now thought t ...

of the Pyrenees, the extinct

volcano A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates ...

es of Central France,

gneiss Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures an ...

es, and crystalline

schist Schist ( ) is a medium-grained metamorphic rock showing pronounced schistosity. This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes ...

s. He wrot
"''Structures et classification des roches éruptives''"
(1889), but his more elaborate studies were carried out with

Ferdinand André Fouqué Ferdinand André Fouqué (21 June 1828 – 7 March 1904) was a French geologist and petrologist. He was born at Mortain, in the Manche ''département''. At the age of twenty-one he entered the École Normale Supérieure in Paris, and from 1853 ...

. Together they wrote on the artificial production of

feldspar Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feld ...

nepheline Nepheline, also called nephelite (), is a rock-forming mineral in the feldspathoid groupa silica-undersaturated aluminosilicate, Na3 K Al4 Si4 O16, that occurs in intrusive and volcanic rocks with low silica, and in their associated pegmatite ...

and other minerals, and also of

meteorite A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon. When the original object e ...

s, and produced "''Minéralogie micrographique: roches éruptives françaises''" (1879) and "''Synthése des minéraux et des roches''" (1882). Levy also collaborated with Alfred Lacroix i
"''Les Minéraux des roches''"
(1888) and "''Tableau des minéraux des roches''" (1889).Tableaux Des Minéraux Des Roches
Rare Mineralogy Book: Michel-Lévy, Auguste Michel-Lévy interference colour chart (21257606712)

Michel-Lévy interference colour chart (21257606712)

Michel-Lévy pioneered the use of

birefringence Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light. These optically anisotropic materials are said to be birefringent (or birefractive). The birefrin ...

to identify minerals in

thin section In optical mineralogy and petrography, a thin section (or petrographic thin section) is a thin slice of a rock or mineral sample, prepared in a laboratory, for use with a polarizing petrographic microscope, electron microscope and electron ...

with a

petrographic microscope A petrographic microscope is a type of optical microscope used in petrology and optical mineralogy to identify rocks and minerals in thin sections. The microscope is used in optical mineralogy and petrography, a branch of petrology which ...

. He is widely known for the Michel-Lévy interference colour chart, which defines the interference colors from different orders of birefringence. He also created classification schemes for igneous rocks which accounted for their mineralogy, texture, and composition, and showed that igneous rocks of different mineralogies could be formed from the same chemical composition, with different conditions of crystallization.

References

External links

Modern Microscopy
Michel-Lévy Interference Color Chart

Michel-Lévy Birefringence Chart

Michel-Lévy Birefringence Chart

, Michel-Lévy Birefringence Chart

Michel-Lévy Color Chart. {{DEFAULTSORT:Michel-Levy, Auguste 1844 births 1911 deaths Scientists from Paris French geologists Members of the French Academy of Sciences