moqui marbles, utah Iron oxide concretions (Moqui marbles) Moqui Marbles, hematite concretions, from the Navajo Sandstone of southeast Utah. Scale cube, with "W", is one centimeter square. The Navajo Sandstone is also well known among rockhounds for its hundreds of thousands of iron oxide concretions
Tracey Broome : Sig and Stain. Test tiles are out of the bisque, I have put some black iron oxide wash on them and they will go back in for an 04 firing. They are chrome oxide, red iron oxide, cobalt carbonate, copper carbonate and rutile colored terra sigs and washes.
Jim Snitily 2200 F Cone 5 - I brushed three coats in different directions of the black ( also added 2% black iron oxide to the base) Then applied 2-3 coats of the crawl with 4 inch wide brush medium thick, just so it goes on smooth, not runny. When that dries, it will crack and that shows its thick enough