Mexican lace agate is a banded chalcedony, a microcrystalline variety of quartz, characterised by tightly looped and folded layers of colour that suggest fine lacework when sawn and polished. The principal commercial deposits lie in northern Mexico, in the states of Chihuahua, Coahuila and Aguascalientes, where the host rock is generally Tertiary rhyolite and andesite. Within this regional category sit several named varieties, including crazy lace agate, pink lace agate and the so-called Mexican fire agate from the same volcanic terrain.

Chemically, the material is silica with traces of iron oxide and manganese responsible for the warm reds, oranges and pinks that dominate the Mexican palette. Refractive index is approximately 1.53 to 1.54 and specific gravity around 2.60, with hardness of seven on the Mohs scale, making the stone appropriate for everyday wear including rings. The take-up of polish is high and there is no cleavage, which suits free-form lapidary work.

The lacework pattern arises from rhythmic banding of silica gel into narrow vesicles in the volcanic host, with the bands subsequently folded by deformation of the host or by uneven precipitation. The result is a tight succession of curls, loops and circular patches that distinguish the material from the more open banding of, for instance, Botswana agate or the parallel banding of Brazilian agate. The pattern is the principal grading factor, with strong contrast between bands and a clean, undisturbed lace structure commanding the highest prices.

The cutting is almost always cabochon or flat slab, oriented to display the lace pattern at its most complex. Beads, freeforms and intarsia panels are also common. Heat treatment is sometimes applied to deepen the warm tones, and dyeing of pale material in pink and red is documented. Both treatments should be disclosed at the point of sale.

The market for Mexican lace agate is steady rather than spectacular. The stone is widely available, generally affordable, and a familiar material in Southwestern and Mexican cooperative jewellery. Higher-grade pieces with intricate undamaged lace pattern and saturated colour are increasingly sought after by collectors of cabochon material. The trade occasionally elevates particularly fine pieces to named designations such as crazy lace agate, but there is no formal grading system.