Would a white Chalcedony Cienega point in a 9-10 grade be more rare than a Chaco Corner Notched point of the same grade? Both are from Zapata Co., TX.
silver

Both types also range into Northern Mexico, however the Cienega ranges across northern Nuevo Leon into Eastern Coahuila. The Charco ranges into north central Nuevo Leon to western Tamalipas. The Cienega is rarely found North of the Rio Bravo. Both could be considered rare finds, but more so with Cienega. Hope this helps.

Yes, it does help but I wonder how these artifacts could've shown up in Zapata Co.? They came from a collection from that area I believe & I can only assume they were collected from a particuliar area, which may've been the only area where the point makers were established.
Silver

Well Silver, you may be right about that within Zapata County. I personally have found good Charco points in Webb County, but have never found a Cienega, and have only seen photos of them found in Maverick, and Val Verde Counties (not far from the River). The Cienega has also been found at Fate bell Rock Shelter site at the Pecos confluence, I fully suspect ground zero for that type is in northern Mexico. Good Luck, and hope you find out more.