Now that I've seen the other picture it looks like they are furrows. Someone might have used an engraving tool to make this coin look cracked. Probably a budding "artist."
Coins can undergo a lot of interesting challenges in the hands of collectors who wish to "improve" them. How about a coin that had glue or some form of varnish on it that had cracked and was then subjected to an acid in an attempt to remove it. The acid may not have attacked the organic coating but did etch the metal exposed by the cracks. Eventually a solvent may have been used to remove the glue or varnish and exposed the etched design.
I have an Indian head that has what looks like black paint in the fields and it looks a little crackly like this one, but acetone did not touch it. I tried paint thinner and goof off as well and nothing seems to touch the black stuff.
Crackle compounds can be added to most paint from milk paint to acrylic to even epoxy ( slow drying) to produce a crackle finish. A clear layer can be used to produce a very interesting organic pattern on fake-wood cabinets and walls. If we see a bunch showing up on eBay... I think a thin clear arcrylic coat would be good as acrylic isn't affected by acids or chemicals readily. http://www.fauxfx.com/pages/a_aquacracklematepage.html
I still think some "artist" used an electric engraver with different sized tips to make it look cracked.