Grains of Sand. Myths and Facts.

Lagoon Island Pearls

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There remains confusion whether sand is implicated in the formation of natural pearls.

For over a century, the myth has been most pearls are formed around grains of sand. This is a myth.

It's been reported in more recent times that grains of sand are not implicated in pearl formation. This is also a myth.

Although there are numerous sub-groups of each, there are only two ways pearls are formed. They are:

1- Modification of epithelial cells.
2- Displacement of epithelial cells

Let's discuss the properties of e-cells for a moment.
E-cells appear in several forms, but only a couple of structures are capable of mineral excretion. These are pallial and vestibular mantles. The former creates and builds the valves (shells) and the latter creates a surface for new growth of the adductor to attach. Mantles have two surfaces. The inner and outer surface. Most important, mineralization only occurs at the outer surface. After all, it is what builds the shell during the life of the creature.

Mineralizing e-cells do not appear spontaneously at any other point in the anatomy. The proverbial "irritation" of non-pallial tissues does not give rise to pearls. Cells divide and multiply, thus only appear next to one another. In nature, shells are not infallible. They can chip, crack or break under a broad variety of environmental stresses. With that, molluscs are able to repair their shells and survive a complete life cycle. When the outer epithelium becomes "perforated", the resulting lesion is already surrounded by viable cells. As they form new cells, bridging occurs. These cells are naturally programmed to occupy space, but only if the space is otherwise unoccupied.

This is displacement. In the case of pearl culture, grafting is a sub-group of displacement. Tissue types being identical, this is homogeneic origin.
In the case of parasites, pearls may occur in other soft tissues. This begs a question. How can this be, if only mantles produce pearls? The answer is simple. Many parasites also have mantles. In pearl grafting, sections of the mantle are cut from the pallial mantle of the donor. Despite the demise of the animal itself, the epithelial tissues remain viable for a period of time postmortem. Although a parasite may die by entrapment, the mantle will continue to grow, especially within the compatible bloodstream of it's host, thus creating a pearl. Tissue types being non-identical, this is xenogeneic origin.

Autoimmunity is in the cell modification group. Mineralizing e-cells do not mineralize 24/7/365. They only precipitate tablets at intervals within the growth cycle.
All living things need calcium to build soft or hard tissues. During quiescence or hibernation, at times of low salinity, while buried in sediments or enduring other stresses, e-cells can revert, changing acid/base pH, hence uptaking reclaimed calcium ions from it's shell to support soft tissue survival. The underlying factors of immune disorders are difficult to describe, even to most experts, so I'll not elaborate, but it's well known blood born parasites (ie) protozoa are implicated. This generally gives rise to pearls with no discernible nuclei, often occurring in higher incidences of two or more, even multiple pearls in a single specimen.
As mentioned, all molluscs have mantles, but they are far from identical. In pearl oysters, pteriods have a partially connected free forming mantle, meaning the organ may be reflected to reveal the outer epithelium with minimal distress to the animal. However, this not the case in pteriomorphs, where the mantle is attached to the base of the periostracum. This is an important point, because unlike pearl oysters, sand which has been trapped in the extrapallial space cannot be sloughed. Instead it must be encased, after all it's adjacent to the outer epithelium. Whereas, in pteriods, mucous with gather the foreign bodies for sloughing. The same applies to other non-pallial tissues and spaces of pteriomorphs.

What are the rates of incidence of "sand pearls" among classes? Benthic and epibenthic creatures are greatly resistant to sand introduced in the EP cavities. This group is mainly clams, which stands to reason because these live the greatest part of their lives buried in substrate, thus incidence is extremely low. Perhaps high as 1:10000. Epifaunal creatures, not so much. They are not evolved to be buried in sediments for extended periods of time, instead live near to the bottom or on top of the sea floor. This presents a greater opportunity for physical damage or infiltration by predators. Mussels are among this category, hence more susceptible to a higher incidence of pearls with sand at the nucleus. In my operation, the rate is about 1:200 or roughly 5%. I have crushed and dissolved several pearls, evidenced by residual plagioclase... yes, sand. A volcanic process, not a biological one.

To summarize, there can be no doubt sand is implicated in the formation of natural pearls, but only in a minority of cases.
 
Yes indeed Dave!
And diatoms, and just so many external "irritants" can help start or promote natural pearl formation. Some being more effective than others. Mollusks are simply amazing creatures.
 
They sure are!

I'm astonished clams don't produce more pearls. I suppose because they live within substrate they're better equipped to deal with mud, sand and gravel. I don't know how many steamers (Venerupis philippinarium) I've eaten in my day, but it's a lot and I've never found a decent pearl. A friend did one time but it was destroyed by cooking.

We don't have quahogs on this coast, but the incidence is definitely higher, but I'd think it's because they're bigger and older.

Geoducks have the most pearls of all the clam species locally, especially ones with "Stinger Syndrome". Commercial divers using a high pressure water hose with a 30 inch nozzle called a stinger which will contact the edge of a shell, causing a fluid embolism which entirely collapses one of the pallial mantles and the cavity becomes packed with sand. That would almost certainly be fatal in other species, but clams are tough. In subsequent years, divers return to the same area and sometimes harvest the survivors.These specimens also had multiple loose pearls in the mantle, all of which had sand at the nuclei. Even after thorugh scrubbing, these images clearly depict grains of sand embedded in the nacre.

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Here's me many years ago diving for geoducks in Spider Anchorage.

David diver.jpg

Dave entering water.jpg
 
I spoke with Laurent Cartier at SSEF about the grain of sand being implicated in Natural pearls. Although theoretically possible, he has never discovered a grain of sand in the thousands of natural pearls he has examined.

If it does happen, and it's so rare that the world's authority of natural pearls has never seen it yet so many people and texts claim it to be the normal method of natural pearl production, it should be debunked as a myth.
 
I spoke with Laurent Cartier at SSEF about the grain of sand being implicated in Natural pearls. Although theoretically possible, he has never discovered a grain of sand in the thousands of natural pearls he has examined.

If it does happen, and it's so rare that the world's authority of natural pearls has never seen it yet so many people and texts claim it to be the normal method of natural pearl production, it should be debunked as a myth.
I would read that paper, if it even exists. Meaning no disrespect to Laurent, it's an opinion not an established fact. If his lab is interested in investigating this, I will contribute specimens for analysis.

I have presented photographic evidence of sand implicated in pearls. Surely you don't mean to suggest I've staged this?
 
This is what Laurent Cartier told me. His critique of the Pearls As One course was specific to the grain of sand. His lab has X-rayed thousands of pearls - basically every fine natural pearl piece that's sold at auction or to a collector has gone through SSEF since natural dealers demand their cert over GIA. He was definitive that he has never, in all his years, found sand inside a natural pearl.
 
This is what Laurent Cartier told me. His critique of the Pearls As One course was specific to the grain of sand. His lab has X-rayed thousands of pearls - basically every fine natural pearl piece that's sold at auction or to a collector has gone through SSEF since natural dealers demand their cert over GIA. He was definitive that he has never, in all his years, found sand inside a natural pearl.
I get that, but my question to you remains unanswered. I've supported my assertion by posting photographic evidence of sand embedded in pearls.

I have also stated that I've observed this several times in my work with natural pearls along with an opinion of rate of incidence.

I'll ask again. Is this staged?
 
I do believe that almost ANYTHING can induce natural pearl formation (especially with Blister pearls, if you remember my Blog post about "Vampire Snails" and "Pearl Fishes").

I Remember watching Electron Microscope photos of ONE (1) Natural Cortez Pearl that I sent for analysis (with a very odd look! See image attached: unusual outer look, like it was "hammered") that had Foraminifers/Diatoms (can't remember which ones, sorry!) in its outer structure, allowing you to believe it might have been the cause of that pearl to form. This from research that was being conducted by Ana Vasilu at the Lab in Granada, Spain some 10-15 years go.

So those odd symmetrical shapes seen on the electron microscope image (see attached) are the aforementioned microscopic invertebrates. So, the evidence says that these organisms were involved...or maybe the pearl sac was already there and then something happened and became "infected" with these invertebrates? Talk about "Pearl CSI". It was not possible to know.

But this was only one pearl out of thousands analyzed...so, statistically this will be an Outlier. I cannot use this evidence to say that this is the case for ALL pearls, instead I have to say: there is inconclusive evidence that foraminifera/diatoms may be involved in natural pearl formation: 1 pearl out of thousands analyzed...and probably out of Millions of Natural pearls in existence.

Nature is always there to Amaze and Confuse us!
 

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Could this be specific to clams, or even the geoducks?
Geoducks have much longer life cycles than most molluscs. Up to 100 y as opposed to 3-10 y in most others.

Ship/Shore processors find these all the time. Workers set aside an average of 6-12 specimens/m3 discarded shells. Milky, chalky when dried, but most from impacted sand within cracked shells or collapsed mantles.

It occurs a lot in marine mussels, especially on the outer shores where sand levels vary and wave intensity is high.

It occurs in scallops commonly and often multiple pearls from a single shell, many with sand at the nuke. Most have sand stuck to the shells.

Those are all extreme environments, though the rate of incidence decreases as the waters become more protected. (ie) farms
 
No, I don't think it is staged. Could this be specific to clams, or even the geoducks?
Geoducks do live surrounded by a sand-bottom environment. Much higher chances of having a sand issue.
 
Geoducks have much longer life cycles than most molluscs. Up to 100 y as opposed to 3-10 y in most others.

Ship/Shore processors find these all the time. Workers set aside an average of 6-12 specimens/m3 discarded shells. Milky, chalky when dried, but most from impacted sand within cracked shells or collapsed mantles.

It occurs a lot in marine mussels, especially on the outer shores where sand levels vary and wave intensity is high.

It occurs in scallops commonly and often multiple pearls from a single shell, many with sand at the nuke. Most have sand stuck to the shells.

Those are all extreme environments, though the rate of incidence decreases as the waters become more protected. (ie) farms
I did not know that Geoducks have these long lifespans!
I remember trying to grow them in my farm many, many years ago...but they simply didn't like living inside cages...totally unsuitable environment and designed to be fully immersed in sand. Frail shells and they just did not grow fast enough.
 
Over here freshwater Margaritifera margaritifera can live to over 100 , it is believed. They have a weird lifecycle which involves babies living in trout gills.
 
Geoducks do live surrounded by a sand-bottom environment. Much higher chances of having a sand issue.
Benthic creatures are better equipped to prevent it. How they deal with it after the fact is common in most species.

Epifaunal mollusks (like mussels) while buried in substrate have more difficulty tolerating it, especially when cracked or obstructed.

Geoducks cannot close entirely, leaving vulnerable soft tissue exposed. If anything, depend on the surrounding sand for protection. They are quite adept at purging sand through the siphons, but visceral and extrapallial infiltration are very different things.

Geoducks hibernate for long periods, sometimes years. That means they live of their shells (and pearls) in the meanwhile. Even as adults, shells can get super thin. They live for days, even weeks out of water if cooled.

They've done well farming geoducks in Washington State. They grow them in sections of water pipe dug deeply into the sand. The yearly quota for geoducks in Canada is <2% of the sustainable annual yield since 1980, so there's not much incentive for aquaculture here either.
 
Show us this "amassed" collection and pearls in your lapidary work?

So you processed millions of pounds you say? By your own admission, the vessel quota was 166,000 lbs, now 50,000. That means you would have had to process every clam aboard for 30-40 years. How can this be, when the greatest portion of harvested geoducks are sold on the live market?

If anyone was pearling at Lagoon Island, I'd know about it and they'd certainly know about me. I've known the owners of that oyster farm for 40 years. I also know most of the operators in the geoduck fleet.

Hmmm? I just happen to know someone who works at that farm occasionally when down on his luck (more often than not), who also tended on a geoduck boat for a couple of seasons. The same person ousted from my jade mining operation for horrid behaviour.

Silica from beef jerky and chapstick?

Not buying any of it, not for one second.
 
I've just deleted a now banned user's posts. Thus, some of Jeremy's & Dave's answers won't make sense (beef jerky and beeswax).
 
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