Stanford PhD researcher found natural Herbertsmithite crystals in an Atacama Desert mine waste pile, purer than any lab-grown specimen, with major implications for quantum spin liquid research.
Key Takeaways
Natural Herbertsmithite from the San Francisco mine near Sierra Gorda, Chile measures Cu:Zn ratio of 2.98:1.02 vs. best lab synthetics at 3.15:0.85, meaning essentially zero magnetic interlayer impurities.
A single boulder yielded ~10g of crystals, roughly 10x the output of a 9-month, $10k+ Stanford lab growth cycle with only 45% success rate.
Magnetic impurities on the zinc interlayer are the central uncertainty in quantum spin liquid (QSL) research; ultra-pure natural crystals could make neutron scattering signatures unambiguous without empirical model extrapolation.
A companion Nature Physics paper (Young Lee lab) provides the strongest evidence to date for a gapped QSL state in Zn-Barlowite and Herbertsmithite; a gapped state implies fault-tolerant exotic excitations useful for quantum computing.
Controversy remains: impurity signal in current measurements is ~5x larger than the intrinsic QSL signal, and a competing result by Kremer et al. challenges assumptions about zinc site occupancy on the Kagome layer.
