On Feb 24, 4:21*pm, "W" wrote:
"songbird" wrote in message

...

W wrote:
What is the most economical source for a large bag of small red lava
rock,
to be used as a replacement for pumice in a succulent soil mixture? * I
also
want to use the red lava rock as a mulch.

* the stuff floats away easily, so not the
best mulch if you get heavy rains, winds or
floods.

Are you confusing lava rock with perlite? * *Perlite definitely floats.
Volcanic aggregates (i.e., either white pumice or red lava rock) sink in
water.

I did a quick test with 10 smallish red lava rocks in a bucket of water, and
they all 10 sank.

--
W

Lava rocks are not pumice. Pumice floats. Having tossed a few hundred
pumice pieces into Crater Lake, I can attest to this. You might also
look at

http://en.wikipedia.org/wiki/Pumice_raft

Chris