[Rockhounds] Volcanos, earthquakes and things

[Jim Murowchick]

Hi Axel, Pete, and everyone--
    I was just wondering--a prismatic piezoelectric crystal will generate a
positive charge at one end and a negative charge at the other when stressed.
Even if the crystals are aligned, wouldn't there be about equal numbers of
crystals in orientations 180 degrees from each other (antiparallel)?  If so,
then the charges on the crystals should effectively cancel each other out in
the rock.
    Also, for quartz, I seem to remember that the piezoelectric effect is
strongest along the a axes.  If so, then even with aligned prismatic
crystals, there would be an infinite number of possible orientations of the
a axes (rotated around the c-axis direction).  Again, any electric fields
produced by compaction would cancel out in the rock.  Does that make sense,
or am I missing something?  Good mental exercise.
Jim Murowchick


On 1/8/08 2:04 PM, "Axel Emmermann" <axel.emmermann at pandora.be> wrote:

> Hi Earl,
> 
> I particularly like the "straws in syrup" analogy. That crossed my mind too
> before I was thrown off by the gravity hoax.
> I just got word that the gravity-link is not proven but rather expelled to
> the realm of the esoteric... Back to the cellar for a fresh box of stale
> ideas ;-)))
> Still, any process that causes polarization of quartz could result in
> possible EM fields upon compression of the rock.
> 
> Yeah, that help ;-)))
> 
> Thin sections and polarized light to determine if any prevalent orientation
> is present? Then squeeze along prevalent c-axis and measure electric field?
> 
> 
> Cheers
> 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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