A suite of agates from Gurasada, Romania have been characterised using powder X-ray diffraction, thermogravimetry and density determinations. A comparison of agate data from Gurasada with 14 other world-wide regions reveals discrepancies in the Gurasada agate information. The crystallite size, density, defect-site water and moganite content demonstrate that these agates can be characteristically divided into two groups. One group reveals properties that are consistent with a contemporaneous formation around the age of the ~75Ma old host. Host rock bentonitisation is a likely silica source for the second group of agates that have apparently formed ~ 55 Ma later. Additionally, a number of the Gurasada agates contain cristobalite that exists as a white rind and within the agate structure.