Bones, Rocks and UV

Hello,

I need help in dealing with an attempt to apply a dating technique
standard in forensics to rock art.  Yes, this is going to be a bit
bizzare, but this is something quite serious.

Of late I have been working with two European university professors. 
One is Peter Pieper (don't laugh, that is his real name) of Dusseldorf
Univeristy, Germany and Ian Kirby of Laussanne Univeristy,
Switzerland.  Pieper teaches archaological and criminal forensics. 
Kirby teaches various topics dealing with the development of the
English language.  Both are also quite expert at Old Norse and love
runestones.

Within the forensics community there is a test that is applied to
bones to determine if they are old or young.  The test is conducted by
shining a UV light on the bones.  If the bones are less than a hundred
years old, any breaks that occured in them (like when the person was
killed) will fluoresce.  Sort of weird sounding, but quite real.  Here
is a link to a forensics page that mentions this.
http://www.dundee.ac.uk/forensicmedicine/llb/ident.htm

My first question is why would this work?  Bone is essentially calcium
carbonate.  Some of the nicest fluorescent samples are of calcite. 
But is calcite inately fluorescent or only so if there are the right
sort of impurities in it?  If calcite is not inately fluoresent, then
bone, regular limestone, etc. should not be fluorescent.  So why would
broken bone flouresce and do so for so long a period of time?

Kirby and Pieper are now trying to extend this technique to rock art. 
They claim they have tested this approach on various types of rocks
and under conditions where the age of a carving (like on gravestones)
was known.  They are quite satisfied that they have something that
works.  I am trying to figure out if there is a theoretical  basis for
it to work.

I was with them in Oklahoma a couple of weeks ago.  We examined a
piece of rock art that is documented to have been seen as early as the
1830's.  On the stone was also some more modern looking "graffitti". 
Also there was a spot on the rock where a sample of the stone was
removed two months ago for geological analyis. The graffitti and the
sample locale fluoresced, the older artwork did not.  The stone
involved here was a sandstone that had gone through some low grade
metamorphism and was quite sturdy.

So does quartz act like calcite where it is not inately fluorescent,
but if it is damaged, will it glow for some period of time?  What
mechanism would allow damaged crystals to fluoresce?  Would this work
for all minerals or just a select few.

If this technique works it would be a big gain to the study of rock
art.  It would be nice if the technique weren't so crude in the date
cutoff.  You would only know if the art was older or younger than a
century.  But for many of the more controversial sites, the person
promoting the "find" is often accused of creating the rock art
themselves as some sort of attention getting scheme.  If Kirby and
Pieper's technique works, then there would at least be no question
whether something is an authentic ancient artifact or a modern hoax.

I can provide more details as needed about all of this.  I just wanted
to present the basic problem to mineralogists for their input.

Thanks ahead of time  

Bart Torbert
[EMAIL PROTECTED]