[Rockhounds] Volcanos, earthquakes and things

[Earl R. Verbeek]

Hi Axel,
 
The idea of quartz growing with c-axes aligned with the gravitational
field is an interesting one, and also easily testable.  Has this ever
been demonstrated?  In plutonic rocks the dominant control is the flow
of viscous magma, which tends to rotate any elongate mineral grain into
parallelism with the flow layers, and also tends to rotate the long
direction of those grains parallel to the flow vectors.  You thus see,
in some plutonic rocks, a strong preferred orientation of elongate
mineral grains, but the orientation is controlled by magma flow
patterns, not gravity.
 
In metamorphic rocks the directions of quartz c-axis orientations are
often strongly aligned, but here the control is tectonic plate movements
setting up strong deformation stresses in the rocks.  There is a vast
literature on this subject (and on the plutonic rocks too).
 
In sedimentary rocks the quartz grains, if they have any elongate
character to them, tend to lie with their long axes parallel to bedding.
The long axes of the grains would naturally tend to be parallel to the
c-axes of the original crystals.  You can also get lineation, with all
the c-axes pointing in the same direction as well as lying within the
plane of bedding.  Here the dominant controls are gravity (which
determines that bedding planes will be horizontal in most cases) and
fluid flow (which determines the direction the c-axes will line up).
 
I think the key point is that oriented quartz grains can be expected in
many types of rock (indeed, have been proven by measurement to be
present), so it might indeed be possible for those grains to exhibit
some cumulative piezoelectric effect during earthquake deformation.
That's a part of the literature I haven't followed.
 
That help?
 
         Cheers-    Earl
 
Dr. Earl R. Verbeek
Resident Geologist
Sterling Hill Mining Museum
P:  973-209-7212
F:  973-209-8505
E:  shmm at ptd.net
 
 
-----Original Message-----
From: rockhounds-bounces at lists.drizzle.com
[mailto:rockhounds-bounces at lists.drizzle.com] On Behalf Of Axel
Emmermann
Sent: Tuesday, January 08, 2008 8:07 AM
To: 'Rockhounds at drizzle.com: A mailing list for rock and gem collectors'
Subject: RE: [Rockhounds] Volcanos, earthquakes and things
 
Hi Kreigh & Kitty & all, 
 
I'm gathering data for a speech on the subject for my club. A somewhat
frivolous speech since none of the below has been confirmed by solid
research as far as I know. More like exploring an idea than a real
speech
;-)))
 
It seems that compression of quartz bearing rock layers generates the
cumulative effect of the piezo-electric field of billions of tiny quartz
crystals. 
The reason for this is that quartz crystals grow with their c-axis
aligned
with the earth's gravitational field. So , any plutonite with
micro-crystals
of quartz would have those crystals aligned following it's orientation
to
the earth's axis at the time it solidified. Pressure on the rock in the
direction of the c-axis of the crystals would generate tiny electric
fields
round each crystal. The effect (although I think that it still needs
some
proof) may be the cause of the so called quake-lights. It may even be
strong
enough to directly influence sensory perception and cause hallucinations
in
persons that are susceptible to it: UFO sightings, alien abduction
stories,
ghost apparitions, feelings of anxiety, elfs, cobolds... A lot of myth
and
perhaps even man's inclination to religion and mysticism may have begun
here.
 
In this respect I would find it logical that if seismic disturbance
creates
strong electrical fields it also causes ELF/VLF emissions.
 
I'm still looking for a way to measure flutuations of the elctric field
of
quartz bearing rock when compressed near breaking point. ;-)))
 
I'd like the opinion of a geologist on this one very much.
 
Cheers
Axel
 
 


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