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.
John

-----Original Message-----
From: The listserv where the buildings do the talking
[mailto:[log in to unmask]] On Behalf Of Lawrence
Kestenbaum
Sent: Monday, November 10, 2008 8:12 PM
To: [log in to unmask]
Subject: Re: [BP] New (maybe) Thread

On Mon, Nov 10, 2008 at 8:01 PM,  <[log in to unmask]> wrote:

> What's the difference between slate and bluestone?

A lot of the Arts Quad at Cornell is built of big blocks of Ithaca
Bluestone.  I'm not a materials guy, but I don't think it looks or
acts like slate.

                                                          Larry

---
Lawrence Kestenbaum, [log in to unmask]
Washtenaw County Clerk & Register of Deeds, http://ewashtenaw.org
The Political Graveyard, http://politicalgraveyard.com
Weblog: Polygon, the Dancing Bear, http://potifos.com/polygon
P.O. Box 2563, Ann Arbor, MI 48106

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