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

geologist A geologist is a scientist who studies the structure, composition, and History of Earth, history of Earth. Geologists incorporate techniques from physics, chemistry, biology, mathematics, and geography to perform research in the Field research, ...

. He was born 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 ...

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 group, and dealt with

pegmatite A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic c ...

s, variolites, eurites, the

ophites The Ophites, also called Ophians (Ancient Greek, Greek Ὀφιανοί ''Ophianoi'', from ὄφις ''ophis'' "snake"), were a Christian Gnosticism, Gnostic sect depicted by Hippolytus of Rome (170–235) in a lost work, the ''Syntagma'' ("arrange ...

of the

Pyrenees The Pyrenees are a mountain range straddling the border of France and Spain. They extend nearly from their union with the Cantabrian Mountains to Cap de Creus on the Mediterranean coast, reaching a maximum elevation of at the peak of Aneto. ...

, the extinct

volcano A volcano is commonly defined as a vent or fissure 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 oft ...

es of Central France,

gneiss Gneiss (pronounced ) 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. This rock is formed under p ...

es, and crystalline

schist Schist ( ) is a medium-grained metamorphic rock generally derived from fine-grained sedimentary rock, like shale. It shows pronounced ''schistosity'' (named for the rock). This means that the rock is composed of mineral grains easily seen with a l ...

s. He wrot
"''Structures et classification des roches éruptives''"
(1889), but his more elaborate studies were carried out with Ferdinand André Fouqué. Together they wrote on the artificial production of

feldspar Feldspar ( ; sometimes spelled felspar) is 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 ''plagiocl ...

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 pegmatit ...

and other minerals, and also of

meteorite A meteorite is a rock (geology), rock that originated in outer space and has fallen to the surface of a planet or Natural satellite, moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical ...

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). Michel-Lévy pioneered the use of

birefringence Birefringence, also called double refraction, 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 described as 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 to identify Rock (geology), rocks and minerals in thin sections. The microscope is used in optical mineralogy and petrography, a branch of petrology which focuses on detailed descr ...

. 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. He named " esterellite" to the blue porphyry of Estérel in 1896.

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