Re: petrified wood

Neale wrote> Wood, for example can be silica, but can also be iron pyrites
or calcium carbonate. It depends largely on the depositional environment
the fossil began forming in.>
     It seems to me that the petrified wood sold in the United States as
aquarium rock must be silica based.  I have purchased petrified wood for
aquariums in Ohio, North Carolina, and Alabama over a period of over thirty
years.  All of the pieces look very simular and none have raised the pH.
 Wouldn't calcium carbonate raise the pH and the Carbonite Hardness?  The
tanks which have the petrified wood are always the healthiest.  My theory was
that it was very poruos silica and that the "good" bacteria colonized on it
easily-sort of like the silica bio beads that are selling for twenty dollars
for six or eight ounces.  I keep the petrified wood in bare bottom and
planted tanks.  Most of the tanks are full of angel fish or discus.  The
water is monitored very closely and kept at a pH of 6 or below.  Does anyone
know where this petrified wood might be collected.  If it is from the
American south west and Mexico (  If this is the wood Bill was refering to I
am sorry for reasking the original question) does anyone know what it would
be made of? What will happen if we put Iron pyrites in our tanks?  
Mary Sigman
Sigmanfam at aol_com