Carl Friedrich Christian Mohs (; 29 January 1773 – 29 September 1839) was a German
chemist
A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties. Chemists carefully describe th ...
and
mineralogist
Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts. Specific studies within mineralogy include the proce ...
. He was the creator of the
Mohs scale of mineral hardness
The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material.
The scale was introduced in 1812 by th ...
. Mohs also introduced a classification of the crystal forms in crystal systems independently of
Christian Samuel Weiss
Christian Samuel Weiss (26 February 1780 – 1 October 1856) was a German mineralogist born in Leipzig.
Following graduation, he worked as a physics instructor in Leipzig from 1803 until 1808. and in the meantime, conducted geological studies of ...
.
Early life
Mohs was born in
Gernrode
Gernrode () is a historic town and former municipality in the Harz District, in Saxony-Anhalt, Germany. Since 1 January 2014, it has been part of Quedlinburg.[Harz
The Harz () is a highland area in northern Germany. It has the highest elevations for that region, and its rugged terrain extends across parts of Lower Saxony, Saxony-Anhalt, and Thuringia. The name ''Harz'' derives from the Middle High German ...]
mountains Germany. He showed a clear interest in science at an early age and received private education before entering the University of Halle.
Education
Mohs studied
chemistry
Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...
,
mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
and
physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
at the
University of Halle
Martin Luther University of Halle-Wittenberg (german: Martin-Luther-Universität Halle-Wittenberg), also referred to as MLU, is a public, research-oriented university in the cities of Halle and Wittenberg and the largest and oldest university i ...
. In 1798 he joined the
Mining Academy in
Freiberg
Freiberg is a university and former mining town in Saxony, Germany. It is a so-called ''Große Kreisstadt'' (large county town) and the administrative centre of Mittelsachsen district.
Its historic town centre has been placed under heritage c ...
,
Saxony
Saxony (german: Sachsen ; Upper Saxon: ''Saggsn''; hsb, Sakska), officially the Free State of Saxony (german: Freistaat Sachsen, links=no ; Upper Saxon: ''Freischdaad Saggsn''; hsb, Swobodny stat Sakska, links=no), is a landlocked state of ...
, being student of
Abraham Gottlob Werner
Abraham Gottlob Werner (; 25 September 174930 June 1817) was a German geologist who set out an early theory about the stratification of the Earth's crust and propounded a history of the Earth that came to be known as Neptunism. While most tenet ...
.
Career
After assuming the position of a foreman at a
mine
Mine, mines, miners or mining may refer to:
Extraction or digging
* Miner, a person engaged in mining or digging
*Mining, extraction of mineral resources from the ground through a mine
Grammar
*Mine, a first-person English possessive pronoun
...
in 1801, Mohs moved in 1802 to
Austria
Austria, , bar, Östareich officially the Republic of Austria, is a country in the southern part of Central Europe, lying in the Eastern Alps. It is a federation of nine states, one of which is the capital, Vienna, the most populous ...
, where he was employed in trying to identify the
mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...
s in a private collection of the banker J. F. van der Nüll. Mohs described this collection, a catalogue was printed and published.
In 1812 he moved to
Graz
Graz (; sl, Gradec) is the capital city of the Austrian state of Styria and second-largest city in Austria after Vienna. As of 1 January 2021, it had a population of 331,562 (294,236 of whom had principal-residence status). In 2018, the popul ...
where he was employed by
Archduke Johann in his newly established museum and science academy, which was subsequently divided into the
Joanneum and the
Graz University of Technology
Graz University of Technology (german: link=no, Technische Universität Graz, short ''TU Graz'') is one of five universities in Styria, Austria. It was founded in 1811 by Archduke John of Austria and is the oldest science and technology research ...
. In 1818 Mohs was appointed successor of his former professor at the Freiberg Mining Academy A. G. Werner, who died in 1817.
In 1826 Mohs became full professor of mineralogy at the
University of Vienna
The University of Vienna (german: Universität Wien) is a public research university located in Vienna, Austria. It was founded by Duke Rudolph IV in 1365 and is the oldest university in the German-speaking world. With its long and rich histor ...
.
At the same time he was assigned curator of the Imperial Mineralogical Collection, in which the van der Nüll collection of minerals was incorporated in 1827.
In 1835 Mohs resigned. He became Bergrath which meant being an imperial counselor in charge of mining affairs, published under orders from his department an instruction on mining
and was commissioned with the establishment of a montanistic museum in Vienna.
Mineral properties
As part of this task, he started classifying minerals by their physical characteristics, instead of their chemical composition, as had been done traditionally. This emphasis on physical characteristics was at odds with the prevailing chemical systematics. However, both
Theophrastus
Theophrastus (; grc-gre, Θεόφραστος ; c. 371c. 287 BC), a Greek philosopher and the successor to Aristotle in the Peripatetic school. He was a native of Eresos in Lesbos.Gavin Hardy and Laurence Totelin, ''Ancient Botany'', Routledge ...
and
Pliny the Elder
Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, naturalist and natural philosopher, and naval and army commander of the early Roman Empire, and a friend of the emperor Vespasian. He wrote the encyclopedic '' ...
had compared the relative hardness of minerals known to them in the
ancient world
Ancient history is a time period from the beginning of writing and recorded human history to as far as late antiquity. The span of recorded history is roughly 5,000 years, beginning with the Sumerian cuneiform script. Ancient history cove ...
, including
diamond
Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the Chemical stability, chemically stable form of car ...
and
quartz
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...
. They knew that diamond could scratch quartz, so showing it to be harder. This became the basis of the
hardness scale
The Mohs scale of mineral hardness () is a Qualitative property, qualitative ordinal scale, from 1 to 10, characterizing scratch hardness, scratch resistance of various minerals through the ability of harder material to scratch softer material.
...
developed by Mohs. The hardest mineral, diamond was given a value of 10 and softer minerals such as
talc
Talc, or talcum, is a Clay minerals, clay mineral, composed of hydrated magnesium silicate with the chemical formula Mg3Si4O10(OH)2. Talc in powdered form, often combined with corn starch, is used as baby powder. This mineral is used as a thi ...
were given the very low value of 1 (unity). Other minerals were given intermediate values, depending on their ability to scratch another mineral in the scale. Thus
gypsum
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywall. ...
was given the value 2 because it will scratch talc crystals, and
calcite
Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...
the value 3 because it will scratch gypsum. Minerals are also now classified by chemical characteristics, but the physical properties are still useful in field examination.
In 1812, Mohs became a professor in
Graz
Graz (; sl, Gradec) is the capital city of the Austrian state of Styria and second-largest city in Austria after Vienna. As of 1 January 2021, it had a population of 331,562 (294,236 of whom had principal-residence status). In 2018, the popul ...
.
In 1818, Mohs was appointed professor at his alma mater in Freiberg.
In 1826, Mohs was a Professor in
Vienna
en, Viennese
, iso_code = AT-9
, registration_plate = W
, postal_code_type = Postal code
, postal_code =
, timezone = CET
, utc_offset = +1
, timezone_DST ...
.
Personal life
In 1816, Mohs settled in
Vienna
en, Viennese
, iso_code = AT-9
, registration_plate = W
, postal_code_type = Postal code
, postal_code =
, timezone = CET
, utc_offset = +1
, timezone_DST ...
where he enjoyed balloons. In 1818, Mohs moved to
Freiberg, Saxony
Freiberg is a university and former mining town in Saxony, Germany. It is a so-called ''Große Kreisstadt'' (large county town) and the administrative centre of Mittelsachsen district.
Its historic town centre has been placed under heritage ...
. Mohs died during a trip to
Agordo
Agordo ( Local Ladin: ''Agort'', Ladin: ''Ègort'', Austrian German: ''Augarten'') is a town and ''comune'' (municipality) sited in the Province of Belluno, in the Veneto region in Italy. It is located about north of Venice and about northwest ...
, Italy in 1839, at the age of 66.
See also
*
Mohs scale of mineral hardness
The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material.
The scale was introduced in 1812 by th ...
Notes
References
*
* Wilhelm von Gümbel: Mohs, Friedrich. In: Allgemeine Deutsche Biographie. Band 22, Duncker & Humblot, Leipzig 1885, S. 76–79.
* Josef Zemann: Mohs Friedrich, Montanist, Mineraloge und Kristallograph. In: Österreichisches Biographisches Lexikon 1815–1950 (ÖBL). Band 6, Verlag der Österreichischen Akademie der Wissenschaften, Wien 1975, , S. 345.
* Friedrich Mohs. In
Austria-Forum* Johannes Uray, Chemische Theorie und mineralogische Klassifikationssysteme von der chemischen Revolution bis zur Mitte des 19. Jahrhunderts. In: Berhard Hubmann, Elmar Schübl, Johannes Seidl (eds.), Die Anfänge geologischer Forschung in Österreich. Beiträge zur Tagung „10 Jahre Arbeitsgruppe Geschichte der Erdwissenschaften Österreichs" von 24. bis 26. April 2009 in Graz. Graz 2010, S. 107–25.
External links
*
{{DEFAULTSORT:Mohs, Friedrich
19th-century German geologists
German mineralogists
19th-century Austrian geologists
Austrian mineralogists
Burials at the Vienna Central Cemetery
1773 births
1839 deaths
Honorary Fellows of the Royal Society of Edinburgh
Freiberg University of Mining and Technology faculty