This is a very cool chip. One I've never seen before.

Regarding the cross-hatching you mention, the lines on the edges all seem to run parallel in a southwest-to-northeast direction (if that makes sense), rather than conventional cross-hatching. See the longer parallel lines at the 5:00 and 11:00 positions. (Though it's hard to tell in viewing the chip as scanned. Perhaps Doug can confirm.)

Is it possible that this chip was once in a bezel or money clip that gripped the chip and made these lines? The slightly rounded edges are sometimes consistent with shaving to fit a bezel. This is speculation, and again Doug is best suited to comment with viewing the actual chip.

Regardless, it is neat looking chip.