A hollow silica shell with a chalcedony rind on the outside and a lining of small quartz crystals in the cavity.
They're sold as Tabasco geodes, which is a misnomer. The state of Tabasco is about 800 kilometres away on the Gulf coast. These come from Rancho Agua Blanca in Tabasco Municipality, in Zacatecas, a different place that happens to share the name. Most labels also misspell the ranch as Aqua Blanca. This listing has it right, which is the whole reason the origin line is there.
Undyed and uncoated. The colour is what the silica came out of the ground with.
Mineral: Quartz (silicon dioxide, SiO₂), a chalcedony rind with druzy quartz inside
Crystal system: Trigonal
Origin: Rancho Agua Blanca, Tabasco Municipality, Zacatecas, Mexico
Hardness: 7 on the Mohs scale; hard, though the rind is thin and will crack if dropped
Treatment: None
Dimensions: 1.81 x 1.02 x 2.77 cm
Weight: 16.84 g
You will receive the exact piece photographed.