John Walsh wrote:
> Bluestone is a dark-colored and indurate "dirty" sandstone. It's rift is
> generally somewhat thick resulting in inch-scale flags. Slate is a
> finer-grained and lightly metamorphosed mudstone/siltstone. The rift is
> usually more penetrative resulting in thinner slabs and there usually is a
> secondary potentially weak plane at an angle to the first. That's a
> geologists view. Architecturally, they look different in texture though
> often similar in color. Engineeringally (yes, that's a word), bluestone is
> usually harder and stronger.
>
thnk u John
--
To terminate puerile preservation prattling among pals and the
uncoffee-ed, or to change your settings, go to:
<http://listserv.icors.org/archives/bullamanka-pinheads.html>