The origin of the so called “Tabasco Agates” is Rancho Agua Blanca near Tabasco in Zacatecas. These nodules are reaching sizes up to 10 cm and are having a green coloured skin from the mineral seladonite. If the agate in the center is translucent, this green skin can cause colours reminding jade. The usual colours of “Tabasco agates” is bluish-grey in combination with white banding. Extremly rare are yellowish or red bandings. Typically formations in “Tabasco-Agates” are single standing spherulithics and whitish dots, the formation of chalcedony stalactites and ”water-level-agate”. Unusual is the formation of agatized centers in the middle of mega-quartz. Absolutely rare are intensively coloured plumes.
More information about this locality is given by Brad L. Cross in his book “The Agates of Northern Mexico”, page 112 - 113.