This is a problem I identified while taking some photos for the H&H wiki.
When you place stone in this orientation:
XX
XO
Where X is some stone (I used dolomite) and O is hornblende, the hornblende tile paves like this:
Where the texture on the tile is weirdly fragmented and broken in half. I've only tested this once, but I tried placing other types of stone in the same orientation and only hornblende has the texture fragment like that.