Chiapas amber

Mexican law recognises seventeen different colours of it, and they run from white through orange and pink to green, blue and black.

Chiapas amber, also called Mexican amber, formed during the Early and middle Miocene in what is now southwestern North America. Most of it comes out of fossil-bearing rocks in the Simojovel region of Chiapas, and much of that material is 23 to 27 million years old, of a quality comparable to Dominican amber. Some of it is clear the whole way through, and some carries fossilised insects and plants, which is what makes it scientifically valuable as well as ornamental. As with other ambers, the inclusions run wide: insects and other arthropods, plant fragments, even epiphyllous fungi.

The largest mine is at Simojovel itself, a small village 130 km from Tuxtla Gutierrez, and it produces the overwhelming majority of the state's amber. Most of what is recovered goes into jewellery, pendants, rings and necklaces. Since pre-Hispanic times the peoples of the region have held amber to have healing and protective properties.

A paper describing a fossil scorpion shows how the material actually reaches science. The specimen came from a hand-made pit at the Guadalupe Victoria site near Simojovel, an area comprising two Indigenous settlements. A local farmer found the raw piece and took word of it to the director of the Museo del Ambar in San Cristobal de Las Casas. The provenance was then checked with infrared and X-ray spectroscopy and confirmed by field geology tracking the outcrop itself.

The rock tells you what the place used to be. The amber-bearing section is organic-rich lignite, the residue of decayed plants, sitting within sandstone that ranges from coarse to fine, with ripple cross-lamination, friable shales, bentonite-like clay and a great deal of brown and red iron oxide and pyrite. Below it lies a transitional-marine sequence full of shells, corals and bioclastic limestone. Forest, then shoreline, then twenty-odd million years.

Buy from the Simojovel cooperatives and the museum in San Cristobal, and be aware that imitations are common.