TT004 Marcos: This is a big piece that was found by Joe Guilliory and is a EX: Barry Holleron piece. This Marcos was recovered in Comal County, Texas and is of a gray colored chert. Measures 3 7/8" x 1 1/2". The artifact is unique in appearance as one barb is completely sharpened away as the knife was obviously used as a knife. Just a great looking piece with lots of history. And yes it does come with a Certificate of Authenticity that was issued by Dwain Rogers on June 23, 2008.