From:
"John Vancamp" <jvcstnwrks@zzzzzzzzzzzzz>
Date:
Mon, 24 Oct 2005 09:27:30 -0500
Subject:
blue alabaster
Hi all,
Simple test to see if a stone is calcite based (limestone, travertine,
ONYX, marble) place a few drops of vineager on the material, and if it
fizzes, it containes Ca(CO3) -- calcite.
If it doesn't fizz, it's something else. Gary is correct in that the
mineral gypsum is the primary mineral in Alabaster, and gypsum does wind up
as wall board, plaster of paris, etc.
Gypsum is hardness 2 on the mohs scale, while calcite is hardness 3, so if
a stone were pure gypsum, it would be softer than a stone composed of pure
calcite. However, most stones contain traces of other minerals (yes there
are 100% pure varieties of both), and other things such as compactness
(density), moisture content, all of which can affect the apparent "hardness"
To add to the overall confusion---there is a form of non-crystalline quartz
(SiO2--hardness 7) that is also known as onyx.
JVC
Quoted text begins.[Original Message]
From: gary grossman <grossman@--------- >
To: <stone@------------- >
Date: 10/24/2005 5:37:52 AM
Subject: [stone] blue alabaster
Hi Sue, I don't have much information on this stone other than its
ground up for gypsum board. Alabaster is gypsum and the formula is CaSO
4-2H2O -- its calcium sulphate IIRC. OTOH, onyx is calcite Ca(CO3),
which is a different stone entirely.
End of quote.
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