The Minerals of Lithium

Lithium is rare in the cosmos, but the formation of continental crust has concentrated lithium into economic deposits. The 124 recognized Li mineral species occur largely in four geologic environments: (1) lithium–cesium–tantalum (LCT) granitic pegmatites and associated metasomatic rocks; (2) highly peralkaline pegmatites; (3) metasomatic rocks not directly associated with pegmatites; (4) manganese deposits. The geologically oldest Li minerals are reported from LCT pegmatites and date to 3,000–3,100 Ma, a critical period in the evolution of the continental crust and the rate of its generation. This suggests a link between the earliest appearance of LCT-family pegmatites and the onset of plate tectonics, consistent with the correlation between the observed abundance of LCT-family pegmatites and supercontinent assembly.

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Lithium — 200 Years: Meeting Report

Lithium was discovered in 1818 in petalite from pegmatites on Utö (Sweden), an island in the Stockholm archipelago, by Johan August Arfwedson (1792–1841), a student working in the laboratory of Jacob Berzelius (1779–1848), the famous Swedish chemist. To commemorate the 200th anniversary, the Swedish Mineralogical Society (SMS), with the support of the Swedish Museum of Natural History, organized a symposium held at the museum (Fig. 1) followed by a two-day field trip to Utö Island, where it is still possible to collect petalite and other lithium minerals and to study the geological context of the lithium–cesium–tantalum (LCT) pegmatites in which the lithium minerals occur.

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Boron: From Cosmic Scarcity to 300 Minerals

Boron is rare in the cosmos because its nucleus is “fragile.” So, how does one get from the interstellar medium, where boron was first produced, to Earth’s upper continental crust where boron is concentrated in deposits containing remarkably diverse suites of boron minerals? Processes that led to the formation of continental crust also concentrated boron, which is preferentially incorporated into melts and aqueous fluids. Deposits with high boron-mineral diversity include granitic pegmatites, peralkaline intrusions, boron-enriched skarns, and evaporite deposits. Despite the loss of boron minerals from the geologic record due to their ready solubility in water and breakdown at low temperatures, the increase in boron-mineral diversity with time is real, and is accelerated during supercontinent assembly.

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Boron — The Crustal Element

Figure 1. This photograph, which was acquired on October 30, 2013 by an astronaut on the International Space Station, shows one of the largest borate mines in the world (Rio Tinto Borax Mine). The mine is located northwest of Boron, California (USA). The borate minerals in the deposit—largely borax, Na2B4O5(OH)4·8H2O, kernite,  Na2B4O6(OH)2·3H2O, and ulexite,  NaCaB5O6(OH)6·5H2O — formed in…

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