Chiapas produces some of the finest amber in the world, and this small museum in the south of the historic centre is the best introduction to it. The amber deposits of the Simojovel area in northern Chiapas are 25–30 million years old, formed when resin from trees of the Hymenaea family dripped into ancient tropical forests and hardened over geological time. What makes Chiapas amber especially interesting is the exceptional quantity and variety of inclusions: insects, plant material, air bubbles, even small lizards, caught in the resin and preserved across tens of millions of years.
The museum displays pieces ranging from raw amber through worked jewellery to scientific specimens showing inclusions. Explanatory panels cover the geology, the mining process (largely artisanal), and the history of amber use in pre-Columbian Mesoamerica, where it was carved into ceremonial objects and traded widely. A small shop sells amber jewellery at prices somewhat better than the market stalls outside.
There is a second amber museum, the Museo Mesoamericano del Jade, nearby on Real de Guadalupe — if you are interested in pre-Columbian craftsmanship you might visit both, though they cover different ground.