[Clayart] Crystal shape and health

Mon Jul 8 04:00:26 UTC 2024

Look up "devitrification of glass" for a good start.     I think I hear my Mum calling (ha)......  Seriously with regrets, I must attend to other pressing concerns.

Perhaps someone else will kindly enter this discussion.

Misneach,

David Woof...............................................................................................................................................................
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From: Clayart <clayart-bounces at lists.clayartforum.com> on behalf of joel joelfink.net via Clayart <clayart at lists.clayartforum.com>
Sent: Sunday, July 7, 2024 6:51 PM
To: Clayart international pottery discussion forum <clayart at lists.clayartforum.com>
Cc: joel joelfink.net <joel at joelfink.net>
Subject: Re: [Clayart] Crystal shape and health

Okay, I have thought more about this. In amorphic silica (glass) the bonding system is not regular. In silica deposits, I have assumed that the bonding is regular. Am I wrong? If not, what is the difference between the irregular bonding angles of glass, and the perfect symmetry of quartz crystals? Or, are the bonding angles regular in glass, but missing in such a way as to prevent a crystal matrix from forming?

Joel.
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From: Clayart <clayart-bounces at lists.clayartforum.com> on behalf of joel joelfink.net via Clayart <clayart at lists.clayartforum.com>
Sent: Sunday, July 7, 2024 5:01 PM
To: Clayart international pottery discussion forum <clayart at lists.clayartforum.com>
Cc: joel joelfink.net <joel at joelfink.net>
Subject: Re: [Clayart] Crystal shape and health

>>>Quartz has equally strong SI-O bonds in all directions so cleavage is nonexistent.<<<

Thanks! That's very helpful.

Joel.
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From: Clayart <clayart-bounces at lists.clayartforum.com> on behalf of David Woof via Clayart <clayart at lists.clayartforum.com>
Sent: Sunday, July 7, 2024 2:59 PM
To: Clayart international pottery discussion forum <clayart at lists.clayartforum.com>
Cc: David Woof <woofpots at hotmail.com>
Subject: Re: [Clayart] Crystal shape and health

Quartz has equally strong SI-O bonds in all directions so cleavage is nonexistent.  Thus it must shatter with an internal eruption of force in opposition to the direction of externally applied force.  As also in shattered Glass, the resulting fragments are sharp edged shards and bits all the way to fine micro bits.
Interestingly "beach glass" has had the sharpness "tumbled off" by wave action in combination with sand.
Same process and results for the bits and pieces of beach quartz which once long-ago had been fractured from larger parent masses of quartz by varying geologic forces.

Misneach,

David Woof..............................................my Snarky little Raven-Haired Muse is attempting humor regarding the sea producing mineral "Beach Quartz" and the "Sea Glass from Quarts" some people create during their Midnight to 5 :00 AM "Beach Bacchanals." She is becoming frustrated and I think it best to chase her down the catwalk to the dock for an attitude adjusting belly-flop ducking in the Rio Ko'Kwel.
Tide is coming in so in the brackish water the little Vixen is sure to float like a wind skittered leaf.   She trained with the Seals, so she is proficient in under water combat and similar activities.  (Use your wildest imaginings .....to where this afternoon is likely to go..........unchecked, untied, unchained.)

P.S. If I don't survive this .....ya'll can come and get my pottery stuff <);>0)==}=======<
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From: Clayart <clayart-bounces at lists.clayartforum.com> on behalf of joel joelfink.net via Clayart <clayart at lists.clayartforum.com>
Sent: Saturday, July 6, 2024 9:56 PM
To: Clayart international pottery discussion forum <clayart at lists.clayartforum.com>
Cc: joel joelfink.net <joel at joelfink.net>
Subject: Re: [Clayart] Crystal shape and health

Joe,

Thanks. That is interesting, I had never thought of this. I know the feldspars tend to be classified according to cleavage, like orthoclase, but I've only a smattering of reading on geology. Lots of desire, but little time.

Why doesn't quartz form cleavage planes? It makes sense intuitively since glass is a direction into quartz, with pure quartz being pure glass, at least so far as I know. But, assuming that is correct, is there another reason?

Joel Fink.
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From: Clayart <clayart-bounces at lists.clayartforum.com> on behalf of Joseph Herbert via Clayart <clayart at lists.clayartforum.com>
Sent: Saturday, July 6, 2024 8:45 PM
To: clayart at lists.clayartforum.com <clayart at lists.clayartforum.com>
Cc: Joseph Herbert <josephherbert827 at gmail.com>
Subject: [Clayart] Crystal shape and health

Hello,

Adding to Ron’s post on silicosis: quartz crystals, of whatever variety,
show no cleavage planes at all. Thus, quartz, when smashed, breaks like
glass. As Ron says, conchoidal fractures with many sharp edges. Also,
quartz doesn’t dissolve in human body fluids. This means if it’s in your
lungs, it’s not leaving.

Volcanic “ash” has the same fracture characteristics as quartz, but it
forms, uncrushed, as a sharp glass shards when solidified bubbles in the
cooling lava burst. All the bubble surface, and especially the thicker
parts where multiple bubbles join, exist as small sharp particles in the
ash cloud.

Also, asbestos is a mineral with needle-like crystals that can easily
penetrate lung tissue when inhaled. Crystal shape and low solubility make
asbestos dangerous.

In some places road gravel is crushed limestone; this is both good and bad.
Calcite, main constituent of limestone, has three directions of easy
cleavage so all calcite particles, no matter how small, will be blocky with
no sharp pointy parts. Also, calcite should dissolve slowly in the slightly
acid body fluids of the lungs. On the bad side, some limestones have a
significant portion of very fine clay or quartz particles. Limestones
usually form in salt water a long way off shore so only the finest
particles stay suspended long enough to get there. Some other limestones
form in basins with almost no sediment from land, except for wind borne
dust.

I have been thinking about risk tolerance and what I might post about it.

To start with, no, bad, or mis information about hazards leads to decisions
that hold an unknown amount of risk. Such a decision really indicates
nothing about risk tolerance since the person/people involved are not
accurately informed about the range of outcomes they face.

Only slight less bad is a correct risk assessment with a mitigation
recommendation that is misapplied. An example would be fall protection
(body harness and shock absorbing lanyard) where the tether length is
longer than the fall distance. One could argue this is worse than no
protection because the worker has a false feeling of safety.

If you do have good hazard info and you make a good mitigation plan you can
then decide how much protection you feel you need. For example, a tree
trimming task near 220 volt power lines with an electric chainsaw might
call for extra additional ground on the chainsaw case. You might feel that
a fiberglass ladder, rubber gloves, and a double insulated saw case might
make the extra ground unnecessary. In this case, you know the possible
electrical shock risk and might accept the risk of the ungrounded tool.
Would you also do the task alone? Having someone there to call for help is
vital. In industry no one should be allowed to work alone. There are
hundreds of examples why one should not perform a task with risk alone.

>From my limited experience, I think potters may have a higher risk
tolerance than some other groups. This may be because of frequency of
performance. In industry, a dangerous job might be performed once a year or
less. Also that job may be performed by different groups each time. If
there is a dangerous task associated with firing a kiln, a potter may do
that task many times each year and is always the person who does it.

Frequency of performance makes one very familiar with the task, which is
good, but may make one less alert, which is bad. If something unusual
happens, all that experience may not apply and the performer is required to
safely preform a new task immediately without planning.

Just some thoughts

Joe
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