Actually Olivia, even though Pyrite may be softer than hardened steel, I had a Nakayama Asagi stone which I had purchased from So Yamas.h.i.t.a (obscenity filter work around). It was a beautiful stone. On close inspection it had noticeable albeit very small pyrite inclusions. These inclusions during honing would at times release from the Asagi stone. Upon close inspection using my stereo microscope at the time, I surmised that the Pyrite was causing some micro-chipping of the razors edges. I was honing carbon steel razors that did not exhibit micro-chipping when other high grit stones were used. So and I ended up surmising that while the softer Pyrite had no ill effects on woodworking tools like plane irons and chisels with th more obtuse bevel angles, etc., the Pyrite was having an impact on the finer edges of straight razors.
All in all So went above and beyond in rectifying the situation by sending me, someone unknown to him, TWO excellent Asagi specimens from Australia to the U.S. (while he had not even yet received the one I returned to him as it was still in transit back to him) to work with and choose the one that I wanted as a replacement. I picked one and Bill_S ended up buying the other one. Apparently Lynn tried Bill_S's Asagi at the recent Razorcon meet and was equally impressed.
Here are some pics of the original returned Asagi and its Pyrite inclusions since I know you like hones. The graduated lines of the reticle are in millimeters:
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Chris L