Possibly not mentioned anywhere because it is probably not a die chip. Seems like a strange place for a die to break down. I think the chips usually form along the edges of the design? I'm certainly not an expert on such things so could be wrong (and happy to be corrected).
The photo below shows some die chips on 10c coins. From top left 1980, 1990, 1999 x4, 2001, 2004 and 2010.
