I've found some real find agates hunting around that area. Used to do lapidary work and found green banded agates up on the Christ hill near Rio Grande City. Right on past the town of Falcon there used to be a place rock clubs had permission to hunt. Found a lot of agatized snails and coquina's. I still have some of the snails but the coquina's, as small as they are, have long since disappeared.
The subject of Starr and Zapata counties got me to thinking about some material I used to find there that looked like alibates or tecoves. Has anyone found or have a comment about this stuff? "Stuff" is a highly technical term that I use.
Never found anything like alibates when hunting there, did find a lot of agate and some agatized wood. Also, some of the points that I found there were of the same flint that is common in points found in Mexico. A lot of carryover of material. The Mexico flint is of a drab black or black and white type.