I received a Sioux Quartzite stone, from @joamo, a while back, and fixed a few fissures in it. Here is the thread. http://theshaveden.com/forums/threads/fixing-fissures-in-natural-stone-hones.58010/ The process worked really well. I was able to use it on a few razors I honed today, and and look at the scratch marks, on the bevel, under a 60x loupe. I found this stone was somewhere between a 12k and a 15 k stone, more towards the 12k. I also saw that it was a faster cutting stone that the Welsh Slate Stones I used. I used soapy water on the Welsh Stones, and oil on the Sioux Quartzite. I was impressed with the ease of use, without issues. The lighter areas of the stone are denser and less porous.
