Herbertsmithite is a

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. (2 ...

with chemical structure Zn Cu₃( OH)₆ Cl₂. It is named after the mineralogist Herbert Smith (1872–1953) and was first found in 1972 in

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...

. It is

polymorphous Polymorphism, polymorphic, polymorph, polymorphous, or polymorphy may refer to: Computing * Polymorphism (computer science), the ability in programming to present the same programming interface for differing underlying forms * Ad hoc polymorphis ...

with kapellasite and closely related to paratacamite. Herbertsmithite is generally found in and around

Anarak Anarak ( fa, انارک, also Romanized as Anārak) is a city and capital of Anarak District, in Nain County, Isfahan Province, Iran. At the 2006 census, its population was 1,285, in 462 families. It is situated at an altitude of . Anarak is l ...

, Iran, hence its other name, anarakite. Herbertsmithite is associated with copper mineralizations in syenitic porphyries and

granites Granite () is a coarse-grained ( phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies undergro ...

in Chile and in

Triassic The Triassic ( ) is a geologic period and system (stratigraphy), system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago (Year#Abbreviations yr and ya, Mya), to the beginning of the Jurassic Period 201.36 ...

dolomite Dolomite may refer to: *Dolomite (mineral), a carbonate mineral *Dolomite (rock), also known as dolostone, a sedimentary carbonate rock *Dolomite, Alabama, United States, an unincorporated community *Dolomite, California, United States, an unincor ...

formations in Iran. It has also been reported from the Osborn District in the Big Horn Mountains of

Maricopa County, Arizona Maricopa County is in the south-central part of the U.S. state of Arizona. As of the 2020 United States census, 2020 census, the population was 4,420,568, making it the state's most populous county, and List of the most populous counties in the ...

and the Lavrion District Mines of

Attica Attica ( el, Αττική, Ancient Greek ''Attikḗ'' or , or ), or the Attic Peninsula, is a historical region that encompasses the city of Athens, the capital of Greece and its countryside. It is a peninsula projecting into the Aegean S ...

Greece Greece,, or , romanized: ', officially the Hellenic Republic, is a country in Southeast Europe. It is situated on the southern tip of the Balkans, and is located at the crossroads of Europe, Asia, and Africa. Greece shares land borders ...

. Herbertsmithite has a vitreous luster and is fairly transparent with a light-green to blue green color. Herbertsmithite has a

Mohs 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 t ...

of between 3 and 3.5 and is known to have a brittle tenacity. The crystal's density has been calculated at 3.76 g/cm³. Herbertsmithite, in a pure synthetic form, was discovered in 2012 to be able to exhibit the properties of a

quantum spin liquid In condensed matter physics, a quantum spin liquid is a phase of matter that can be formed by interacting quantum spins in certain magnetic materials. Quantum spin liquids (QSL) are generally characterized by their long-range quantum entanglem ...

, a generalized form of

strongly correlated quantum spin liquid In condensed matter physics, a quantum spin liquid is a phase of matter that can be formed by interacting quantum spins in certain magnetic materials. Quantum spin liquids (QSL) are generally characterized by their long-range quantum entanglem ...

due to its

Kagome lattice In geometry, the trihexagonal tiling is one of 11 uniform tilings of the Euclidean plane by regular polygons. See in particular Theorem 2.1.3, p. 59 (classification of uniform tilings); Figure 2.1.5, p.63 (illustration of this tiling), Theorem 2. ...

structure. Herbertsmithite is the first mineral known to exhibit this unique state of magnetism: it is neither a

ferromagnet Ferromagnetism is a property of certain materials (such as iron) which results in a large observed magnetic permeability, and in many cases a large magnetic coercivity allowing the material to form a permanent magnet. Ferromagnetic materials ...

with mostly aligned magnetic particles, nor is it an antiferromagnet with mostly opposed adjacent magnetic particles; rather its magnetic particles have constantly fluctuating scattered orientations. Optical conductivity observations suggest the magnetic state in herbertsmithite is a type of emergent gauge field of a gapless U(1) Dirac spin liquid. Other experiments and some numerical calculations suggest instead that it is a

\mathbb_2

spin liquid (or in other words, has a

\mathbb_2

topological order). To clarify the situation, it is useful to carry out a number of experiments.

References

{{Reflist Copper(II) minerals Zinc minerals Halide minerals Trigonal minerals Minerals in space group 166 Minerals described in 2003