RE: Technique needed for distinguishing CaCO3 and bone

From:Margaret Blount

Dear Gayle,

Calcium carbonate does polarise, it was the original material from which
Nicol Prisms were made (polarisers before polaroid was invented). I was
thinking along the same lines. I am also fascinated by the dinosaur bones,
how exciting, are there any images in the net? By the way the original form
of calcuim carbonate used for Nicol Prisms is called Iceland Spar.
Best wishes

Margaret Blount
University of Cambridge

-----Original Message-----
From: Gayle Callis []
Sent: Wednesday, July 02, 2003 8:48 PM
Subject: Re: Technique needed for distinguishing CaCO3 and bone

Enlighten us please!  Are you working with dinosaur bone?  Is it embedded
in anything?  Why is there calcium carbonate covering the bone?  Is this
from being a cave with water dripping on bones for a long period of time,
like thousands of years, encasing the bone with CaCO3?  like a stalagtite?

I know that dinosaur bone can be embedded in PMMA, even in its extremely
dried state.  I did T rex bone that had laid around for many millions of
years, did no do any dehydration or anything to disrupt the fragile bone
(trabeculae were amazing lifelike and intact).  The bone was infiltrated
ONLY with PMMA embedding mixture, then allowed to polymerize.  After that,
one could cut it with a diamond blade without any problems and no ancient
(extinct) bone damage.

If you can stabilize the bone/CaCO3 in plastic, you should be able to slice
it thinnly (200 um or more) then do image analysis) - the bone, even
extinct bone could possibly be surface stained to distinguish it from the
CaCO3 within the slice.  You could also examine the bone with polarized
light, I don't think CaCO3 polarizes, but not sure on this, some salt
crystals will polarize or you could distinguish the salt crystals from bone
collagen matrix by differences between collagen and crystal - i.e. the
morphology, if you will.  Hmm not sure I said that correctly.

Just some thoughts.

At 07:13 AM 7/2/2003 -0600, you wrote:
>I have several slices of bone with calcium carbonate deposited on them. I
>searching for a good way to readily distinguish between the original bone
>the deposited calcium carbonate. I can usually do so by visual inspection,
>the differences are too subtle for my image analysis software to pick up.
>goal is to be able to quantitatively determine the amount of deposition on
>bone. If someone knows a stain or some treatment that I might be able to do
>that will help bring out the differences between the calcium carbonate and
>bone, I will be most appreciative.
>Thanks for your help.
>Joe Daniel
>Grad student
>Museum and Field studies Program
>University of Colorado at Boulder
Gayle Callis
Research Histopathology Supervisor
Veterinary Molecular Biology - Marsh Lab
Montana State University - Bozeman
S. 19th and Lincoln St
Bozeman MT 59717-3610

406 994-6367 (lab with voice mail)
406 994-4303 (FAX)


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