[Rockhounds] Puzzle

[Axel Emmermann]

Hi Earl, 

I thought of that too but I reckoned that if on is equipped to perform
hardness tests one would not confuse a 5 with a 7.5 ;-)))

There's a lot of phosphates in the Berry - Havey quarry so apatite would be
plausible.
Also Carolyn stated that both the matrix and crystal fluoresce blue (and red
in the perthitic joints between lamellae). That would be indicative of Eu2+.
Apatite would do that too...

Could quartz replacing feldspar retain the perthitic tecture?

Cheers
Axel
 
 

> -----Oorspronkelijk bericht-----
> Van: rockhounds-bounces at lists.drizzle.com
[mailto:rockhounds-bounces at lists.drizzle.com]
> Namens Earl R. Verbeek
> Verzonden: maandag 13 juli 2009 12:05
> Aan: 'Rockhounds at drizzle.com: A mailing list for rock and gem collectors'
> Onderwerp: RE: [Rockhounds] Puzzle
> 
> Hi Axel,
> 
> I looked that up, too, and since it's a pegmatite my thinking immediately
> went to apatite.  The hexagonal form fits, as does that texture
> perpendicular to the c-axis of the crystal that Carolyn mentioned, which
> I've seen before in apatite.  From some localities it does somewhat
resemble
> the perthitic texture of feldspar.  Of course this doesn't fit the
hardness
> measurement, but in some cases, as Pete Richards discussed, it's not at
all
> a straightforward exercise to make a hardness determination.  Let's wait
for
> that photo!  And Carolyn, is the crystal sufficiently well formed that you
> can tell us if the hexagonal shape is truly hexagonal, with six equal
angles
> and all prism faces parallel to the same axis, or is the crystal just
> sort-of hexagonal in a broken cross section?
> 
>        Cheers-   Earl
> 
> -----Original Message-----
> From: rockhounds-bounces at lists.drizzle.com
> [mailto:rockhounds-bounces at lists.drizzle.com] On Behalf Of Axel Emmermann
> Sent: Monday, July 13, 2009 5:48 AM
> To: 'Rockhounds at drizzle.com: A mailing list for rock and gem collectors'
> Subject: RE: [Rockhounds] Puzzle
> 
> Carolyn,
> 
> I looked at Mindat to find the inventory of the Havey Quarry. It turns out
> that there are Havey Quarry #1 and #2 listed as well as the Berry-Havey
> quarry.
> In the latter there is bertrandite to be found.
> You didn't mention the size of the crystal. If it's not too big,
bertrandite
> would be a possible. It's not hexagonal but it can sometimes appear to be.
I
> have no idea how much experience you have (for all I know you may be a
> professional geologist ;-)))
> If this http://www.mindat.org/photo-236703.html was sitting on a matrix in
> the shown position it could fool me for a couple of minutes.
> This one looks even more hexagonal :
http://www.mindat.org/photo-14746.html
> Even more misleading: http://www.mindat.org/photo-148802.html
> 
> Bertandite scores 6-7 on Moh's scale... close enough?
> On the other h	and: if you managed to measure a hardness of 7.5
with some
> confidence the crystal (probably more than one?) must have been
sufficiently
> large to do so.
> One would also expect a greenish fluorescence rather than a blue one if
I'm
> not mistaken?
> 
> I think that the best guess is still feldspar, though.
> A photo would take us a long way....
> 
> Cheers
> Axel
> 
> 
> > -----Oorspronkelijk bericht-----
> > Van: rockhounds-bounces at lists.drizzle.com
> [mailto:rockhounds-bounces at lists.drizzle.com]
> > Namens Carolyn Reynard
> > Verzonden: zondag 12 juli 2009 20:45
> > Aan: Rockhounds
> > Onderwerp: [Rockhounds] Puzzle
> >
> > To the List: I have and interesting puzzle.
> >
> > I collected the specimen at the Havey Quarry, Oxford Maine.
> >
> > It is a crystal that appears to be common beryl as you can determine the
> hexagonal crystal
> > shape.  The hardness is
> > 7.5.  The color is a warm light tan.  The matrix is feldspar.
> >
> > What doesn't quite convince me it is a  beryl is a texture that looks
> likes like perthite and
> > runs the complete length of the crystal into part of the matrix and is
at
> right angles to the C
> > axis. The feldspar matrix fluoresces at bright light blue with red
> perthitic texture as does
> > this crystal..
> >
> > I am wondering if this specimen is a pseudomorph, with perthitic
> microcline after beryl.
> > Would the microcline replacement still retain the hardness of the beryl?
> >
> > I believe this is the important question.  Certainly the crystal
> fluoresces like the microcline
> > but there is the problem of hardness being too great for a feldspar.
> >
> > Nice specimen, just wish I could figure it out!
> >
> > Carolyn Reynard
> >
> 
> --
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