Re: Pearlite & Vermicullite ?
Richard Marsden (redbaron@cix.compulink.co.uk)
Tue, 20 Feb 96 23:09 GMT
In-Reply-To: <199602201334.IAA06787@access2.digex.net>
I know Perlite and Vermiculite as "clay minerals" (clay, as in the type, rather
than the grain size). Derivation from mica is plausible, as is the presence of
fluoride.
Clay minerals tend to be quite complex (often having a sheet crystal structure)
and tend to be derived from other minerals, due to water, etc (hence they are
usually found in clays). Non-biodegradeable I should think, but would expect
them to be fragile (on a short geological timescale).
The complexity means that most kinds occur in a wide variety of compositions.
I have a big book of this sort of thing, and will look it up... (the book is
200 miles away at the moment).
Richard