I took the tiny grains from the John Garsow purchase and put them into the mortar. Obviously, some of the stuff in there isn't lapis. I took out as many purities as I could before grinding. After making a somewhat coarse grind, I mixed it with walnut oil. It was too coarse to use with a brush, but it might work OK with a palette knife. (see left most sample)
So, I put the remainder of the pigment back in and ground it some more (maybe 3 more minutes) Sure enough, it works fine with a brush. (second to left). It is also a little duller. Art Graham told me cobalt can become grayer when the crystals are crushed too fine. I think a similar thing might be happening here with the lapis. The good news is I can choose the best grind for my painting application instead of relying on a paint maker to do that for me. The bad news is I doubt I'll ever have identical batches!
At any rate, the color is much more vibrant, deeper and darker than the Chilean lapis lazuli that I bought in Canada (right two samples)!
