Highly refined and milled rutile for use in ceramics in North America. TamCeramics.com refers to this as potassium titanate, they make it primarily for welding rod and friction products (with particle sizes and shapes adapted accordingly). The ceramic grade is milled to a finer particle size. This is a manufactured product, the potassium is added (they also make a sodium titanate). "Ruflux 61" is likely the same product as "Ruflux P", just milled finer.