One clay type particle I am experimenting with is an aquatic gardening
substrate called Flourite. It is a harder clay than Profile, also heavier.
The kicker is that the plant actually feeds off the clay particles.

I have been using Flourite as a top dressing where moss is not available or
doesn't work. It makes an attractive ground cover. I would like to know from
your experiments if it is better than Turface as a soil ingredient.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)