Herbertsmithite

Herbertsmithite is a mineral with chemical structure ZnCu3(OH)6Cl2. It is named after the mineralogist Herbert Smith (1872–1953) and was first found in 1972 in Chile. It is polymorphous with kapellasite and closely related to paratacamite. Herbertsmithite is generally found in and around Anarak, Iran, hence its other name, anarakite.

Herbertsmithite
Herbertsmithite from Caracoles, Sierra Gorda District, Tocopilla Province, Chile. Size: 4.5 x 4.4 x 2.7 cm.
General
CategoryHalide mineral
Formula
(repeating unit)		ZnCu3(OH)6Cl2
Strunz classification3.DA.10c
Crystal systemTrigonal
Crystal classHexagonal scalenohedral (3m)
H-M symbol: (3 2/m)
Space groupR3m
Unit cella = 6.834 Å
c = 14.075 Å; Z = 3
Identification
ColorLight green, blue-green
Crystal habitAggregates of rhombohedral crystals
CleavageGood on {1011}
TenacityBrittle
Mohs scale hardness3–3.5
LusterVitreous to adamantine
StreakLight green
DiaphaneityTransparent
Specific gravity3.75-3.95
Optical propertiesUniaxial (-)
Refractive indexnε 1.817, nω 1.825
Birefringence0.0080
References[1][2]

Herbertsmithite is associated with copper mineralizations in syenitic porphyries and granites in Chile and in Triassic dolomite formations in Iran. It has also been reported from the Osborn District in the Big Horn Mountains of Maricopa County, Arizona and the Lavrion District Mines of Attica, Greece.[1]

Herbertsmithite has a vitreous luster and is fairly transparent with a light-green to blue green color. Herbertsmithite has a Mohs hardness 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, a generalized form of strongly correlated quantum spin liquid [3] due to its Kagome lattice structure.[4] Herbertsmithite is the first mineral known to exhibit this unique state of magnetism: it is neither a ferromagnet 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[5] suggest the magnetic state in herbertsmithite is a type of emergent gauge field of a gapless U(1) Dirac spin liquid. Other experiments [6][7][8] and some numerical calculations suggest instead that it is a spin liquid (or in other words, has a topological order).

References
  1. Herbertsmithite at mindat.org
  2. "Information on Herbertsmithite on Webmineral". Webmineral.com. Retrieved 2013-03-06.
  3. Shaginyan, V. R.; et al. (2012). "Identification of Strongly Correlated Spin Liquid in Herbertsmithite". EPL. 97 (5): 56001. arXiv:1111.0179. Bibcode:2012EL.....9756001S. doi:10.1209/0295-5075/97/56001.
  4. "MIT researchers discover a new kind of magnetism". Web.mit.edu. 2012-12-19. Retrieved 2013-03-06.
  5. Pilon; et al. (2013). "Spin-Induced Optical Conductivity in the Spin-Liquid Candidate Herbertsmithite". Physical Review Letters. 111 (12): 127401. arXiv:1301.3501. Bibcode:2013PhRvL.111l7401P. doi:10.1103/PhysRevLett.111.127401. PMID 24093299.
  6. Han, Tian-Heng; Helton, Joel S.; Chu, Shaoyan; Nocera, Daniel G.; Rodriguez-Rivera, Jose A.; Broholm, Collin; Lee, Young S. (2012). "Fractionalized excitations in the spin-liquid state of a kagome-lattice antiferromagnet". Nature. Springer Science and Business Media LLC. 492 (7429): 406–410. arXiv:1307.5047. doi:10.1038/nature11659. ISSN 0028-0836.
  7. Fu, M.; Imai, T.; Han, T.-H.; Lee, Y. S. (2015-11-05). "Evidence for a gapped spin-liquid ground state in a kagome Heisenberg antiferromagnet". Science. American Association for the Advancement of Science (AAAS). 350 (6261): 655–658. arXiv:1511.02174. doi:10.1126/science.aab2120. ISSN 0036-8075.
  8. Han, Tian-Heng; Norman, M. R.; Wen, J.-J.; Rodriguez-Rivera, Jose A.; Helton, Joel S.; Broholm, Collin; Lee, Young S. (2016-08-18). "Correlated impurities and intrinsic spin-liquid physics in the kagome material herbertsmithite". Physical Review B. American Physical Society (APS). 94 (6): 060409. doi:10.1103/physrevb.94.060409. ISSN 2469-9950.
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