On 24.10.2011 17:34, dave wrote:
On Sat, 22 Oct 2011 16:14:12 -0400, Tuuk wrote:

Hi
I have a sauna with electric heater 7000watts. Nice area on top to put
some rocks and I see others have suggested lava rocks. What if I put
granite or limestone? That is what I have there now, they haven't
cracked or exploded after spraying water on them. They look nice, some
red, some different colors. Is there any harm in using granite or
limestone apposed to using lava rocks? I am sure they were all the same
a few million years ago,,, any reasons why I shouldn't use the granite
or limestone rocks? Radiation? Emmisions of sometype? inevidable that
they will explode? nuclear meltdown of some kind? I figure the
temperature is around 200 or 300 degs.

Any thoughts please and thanks?

Hot rocks will crack when you pour water on them. That's why you need
igneous stuff like lava (at Barbecues Galore). Get a squirtgun.

Well, some sauna specialists prefer non-porous rocks to others, I am not
sure if the translation "soapstone" is known or correct, but it's dense,
not porous as limestone and has good thermal storing property.
Granite probably don't break easily as it's hard and solid, but
thermal storing properties are not the best.
The one popular stone used is the olivine, there could be several
variants of it.
Don't know the availability of "soapstone" in your area or the price of
it in your quantities but it could be one choice to try, at least on top
layer of stove.

br KB