G'day; One of our Orchidians wrote:-
... I have never heard of bentonite .....
Pardon me for jumping in here but: As a matter of interest, bentonite
is also known as taylorite and is a clay formed only from the
decomposition of volcanic ash. It contains montmorrillonite and
biedellite. The colour ranges from white to pale green, to pale cream,
and after considerable exposure, to yellow and even red and brown.
Ir. absorbs large amounts of water, so that in dry seasons a large
pattern of cracks appears in the ground. cheers, --
John Burgess; @John_Burgess2 of Mapua Nelson NZ