I don't know if the clay is white or red. Red is suitable for seedballs. Posted on the Los Angeles Master Gardener listerv and I'm reposting it here:
Fri Dec 4, 2009 6:11 pm (PST)
We have a lot of raw clay ( unfired flutes) that can be easily used for
building projects. We really don't want it to go to the landfill.
Please pass this on to any Permaculturists or natural builders that you
know. We are located in Boyle Heights.
323.337.7607
kat james
garden releaf