The agate area around stacion Ojo Laguna is situated midway between Sierra Gallego and Sierra El Oso, about 12,5 miles south of Rancho Aqua Nueva.
It is the most southern locality for agates in the Sierra Gallego region. After all the agates were picked from the surface, digging by hand started and rather dangerous tunnels were excavated. This inefficient mining soon stagnated. In 1993 a first bigger lot of rough Lagunas (about 500 pounds) were mined and marketed as Laguna No. 1.
Often you will find green Celadonite, a clay mineral, as coating on the exterior of nodules. The rind is very rough, the shape irregular. Only from La Buja Grande more smooth exteriors are known.
Moss, and carbonates as primary crystallization along the edge are common as well as carbonates as last crystallization in the middle. “Black Widows” is a term for fractures filled with black carbonates, iron and manganese minerals are due for the colour. They are not rare, they are a disappointment for collectors but on the other side a characteristic for Laguna agates.
Further informations are given from Brad L. Cross in his book “The Agates of Northern Mexico”.