Dr Hazen and his team speculate from meteorite and early rock studies that several hundred mineral species, including zircon, quartz, clay and halite salt crystals, formed during this early period of mineral evolution.

ECONOMIST: Minerals

Russell Vreeland and William Rosenzweig, biologists at West Chester University in Pennsylvania, together with their colleague Dennis Powers, a geologist, started analysing Salado salt crystals in the hopes of finding some biological record of this bygone time.

ECONOMIST: Old salts

In conventional crystals, such as salt and sugar, these elements are atoms or molecules.

ECONOMIST: New-age crystals

Crystals of uric acid salt are seen when the patient has gout.

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